Figure 1. The Klearway appliance allows for incremental, 0.25-mm mandibular movements into a therapeutic position. (Figures 1 and 2 courtesy of Great Lakes Orthodontics.)

Figure 2. The Herbst Sleep Appliance is retentive and allows for gradual, precise movements of the mandible without the use of shims.

Figure 3. A Herbst-style appliance is pictured above. It is adjustable by adding spacers. (Figure 3 courtesy of Strong Dental.)

Figure 4. Tap appliance uses a hook on the maxilla to attach to the mandible in order to bring the mandible forward. (Figure 4 courtesy of Johns Dental Laboratories [johnsdental.com].)

Figures 5 and 6. The Lamberg Appliance reports 95% compliance due to its less bulky design. (Fig-ures 5 and 6 courtesy of Dr. Steve Lamberg.)

DIAGNOSIS AND TREATMENT OF OSA

Diagnosis and treatment of OSA present a challenge for the clinician. Establishing that a patient has sleep apnea usually requires a polysomnogram (PSG). This test monitors the patient’s sleep patterns for a night to record the number of episodes of apnea, blood oxygen saturation, heart rate, eye movements, breathing, and other variables descriptive of the patient’s sleep. Medical facilities that offer polysomnography are limited in some areas, and scheduling a night to perform the study can be troublesome for patients with busy schedules. The study can only be performed at a sleep study center.
Establishing the appropriate treatment for OSA can be difficult. Many of the therapies are uncomfortable and unappealing to patients. Furthermore, the involvement of several professionals requires interdisciplinary communication. Treatment of OSA can involve a dentist, an oral surgeon, and an otolaryngologist. This can create very real problems for patients. Correcting OSA primarily requires managing the airflow, the domain of the ear-nose-throat physician. But this can mean moving the jaw forward, a dentist’s responsibility, or sometimes surgery of the jaw, an oral surgeon’s responsibility. The impulse can be strong for one practitioner to take the lead over the others. The situation is further complicated if patient compliance is poor.

PATHOGENESIS

Obstructive sleep apnea is characterized by a collapsing of the tongue back onto the pharynx during sleep. Typically, this is because of a large tongue, small air pathway, or otherwise abnormal throat anatomy. This blockage restricts breathing, lowering the concentration of oxygen in the blood until receptors in the carotid sinus are alerted to higher CO₂ levels in the body, and air hunger is triggered. The patient then regains consciousness, possibly to a limited extent such that he or she does not recall the episode later. Normal breathing is then restored. When the patient falls into a deep sleep, the tongue will collapse again until another apneic episode occurs.
The apnea-hypopnea index (AHI) measures the number of apnea episodes per hour. An AHI greater than 10 is clinically significant. As will be covered later in the article, waking up every 6 minutes can have many negative consequences, as many important processes occur during sleep. Sleep occurs in roughly 4- to 5-hour cycles of light sleep progressing into deep sleep and then REM sleep; OSA interferes with this rhythm.
Being overweight or obese greatly increases one’s risk for sleep apnea. A number of studies correlate above-average neck circumference to prevalence of sleep apnea.⁴ Furthermore, evidence suggests that allergies that affect the nasal mucosa and inhibit proper breathing can increase the likelihood of sleep apnea.⁵

LINKS TO OTHER DISEASES

A growing body of literature suggests a relationship between sleep breathing disorders and cardiovascular/cerebrovascular disorders. Obstructive sleep apnea is associated with atherosclerosis,⁶ hypertension,⁷ high blood pressure,⁸ and type 2 diabetes.⁹ The mechanisms by which sleep apnea influences these problems are not well understood. OSA causes oxygen deprivation, which is thought to interfere with metabolic processes; a study by Savransky, et al¹⁰ showed that intermittent hypoxia, a result of sleep apnea, causes or exacerbates hyperlipidemia and hypercholesterolemia. Leuenberger, et al¹¹ revealed that intermittent hypoxia over even a very short period of time significantly increased sympathetic nervous system activity, caused a stronger chemoreflex response to continuous hypoxia, and elevated blood pressure. This study did not test the effects of periodic hypoxia over extended periods of time, but it is possible that the effect raises blood pressure to a clinically significant extent.
Several studies suggest that those suffering from sleep apnea are at greater risk for involvement in automobile accidents because of daytime sleepiness.¹² Given that traffic accidents are a leading cause of death of American adults, it is especially incumbent upon health-care professionals to inform their patients of the harmful effects of sleep apnea.

DIAGNOSIS

Proper diagnosis of OSA requires a polysomnogram. Subjective surveys of daytime wakefulness are also helpful in determining if an individual is suffering from OSA.
Bruxism is associated with sleep apnea and should be the first signal to alert the dentist of the need to pursue this line of questioning. Sleep bruxism is rarely seen independent of sleep apnea, and it has been shown that effective treatment of OSA completely eliminates sleep bruxism.¹³ Questions about blood pressure and daytime wakefulness will indicate whether a sleep study is in order. Obesity is an important risk factor in developing OSA, and this should be taken into account when referring a patient to a sleep center.
Barsh¹⁴ raised the concern about dentists making their own diagnoses of primary snoring and prescribing oral appliance therapy while ignoring the pathophysiology of snoring and sleep apnea. Dental practitioners are in a position to recognize many telltale signs of sleep apnea, such as a small airway and evidence of severe bruxism. However, it should be emphasized that lack of proper diagnosis and lack of consideration for other treatment modalities that fall outside the realm of dentistry can pose a threat to patients’ health. Cooperation with medical professionals in other fields is essential when dealing with this problem.

TREATMENTS

The correlation between being overweight and having an AHI greater than 10 is strong enough that weight management should be recommended to all overweight patients as a means of controlling sleep apnea. Some have suggested that altering sleep positions will influence the frequency of apneas; sleeping on one’s back increases the likelihood that the tongue will block the pharynx. The effectiveness of this behavioral change is usually not enough to reduce the AHI below 10, but may be sufficient in some cases, thereby saving those pa-tients the need for additional therapy.

Continuous Positive Air Pressure

Continuous positive air pressure (CPAP) pumps air at a determined pressure through the nose. The force of the pressure down the air cavity serves as a splint, which keeps the tongue from collapsing back against the pharynx. CPAP is the most prescribed treatment for OSA and is almost always effective, but patient compliance is poor; compliance estimates are 30% to 40%.¹⁵ The machine can be large and cumbersome, and its use can have irritating side effects such as nasal congestion and throat dryness. In spite of this, there is no substitute for CPAP in severe cases, as surgical methods to treat the disorder are unpredictable. Compliance with CPAP has been shown to reduce the levels of serum risk factors for cardiovascular/cerebro-vascular disease such as cholesterols and apolipoproteins.¹⁶ Patients who are not likely to benefit from oral appliances and are reluctant to accept the CPAP machine should be reminded of the great toll that sleep apnea takes on their health.

Oral Appliances

For patients who cannot tolerate CPAP, an oral appliance may be recommended. These appliances have a number of advantages over CPAP, namely that they are more comfortable, less expensive, and adjustable. The majority of appliances used to correct OSA reposition the mandible; moving the mandible forward also pulls the tongue forward, making it less likely to collapse onto the back of the throat. A few appliances function by retaining the tongue at the front of the mouth using a suction bulb.
While oral appliance therapy to treat OSA is an important treatment option, these appliances are effective in only about half of all cases.¹⁷ Enthusiasm for these appliances is due to patients’ preference for them over CPAP, not because of their success rate. When effective, oral appliances re-duce the apnea-hypopnea index below 10 and restore the patient’s quality of life. The remaining cases are too severe, and use of an oral appliance does not reduce the AHI to an extent that eliminates the adverse effects of sleep apnea. In many cases, the reason for the failure of an oral appliance is that OSA is rarely a localized phenomenon within the airway. For example, OSA can be caused by an obstruction in the pharynx.¹⁸
A study by Almeida, et al¹⁹ indicates that long-term use of a mandibular advancement device can have a clinically significant effect on the patient’s occlusion. In some cases a positive change was observed, although a negative impact was slightly more common. No literature evaluates the degree of mandibular advancement necessary to treat a sleep apnea patient with a particular AHI (Figures 1 to 6).

Surgery

Surgery should be considered as the last resort when treating sleep apnea; it is rare that noninvasive treatments for OSA are ineffective. Surgery is indicated in those cases, or when the patient cannot tolerate CPAP, oral appliance therapy is ineffective, and other treatments such as weight loss have not worked. Evaluation of the airway before surgery requires the cooperation of both an otolaryngologist and oral and maxillofacial surgeon; the potential causes of a blockage are numerous and include the anatomy of the oral and nasal cavities as well as the throat.²⁰
The first widely accepted surgical procedure to treat snoring and sleep apnea was uvulopalatopharyngoplasty (UPPP). This surgery involves removal of the uvula and surrounding soft palate to prevent constriction at the velopharynx. The hypopharynx is often a site of blockage as well, which may explain why UPPP is successful in less than half of all cases. Complications of this surgery are frequent, and include pain, hemorrhaging, and breathing difficulty. Recently, the introduction of surgical lasers has improved UPPP so that complications are fewer and less drastic, but the procedure’s success rate has not improved.²⁰
Another treatment modality is surgery to reposition the hyoid bone. Movement of the hyoid bone affects the tongue’s positioning in the mouth and may alleviate sleep apnea symptoms. By itself, hyoid suspension has a success rate of nearly 60%.²¹ Several published studies evaluated the combination of hyoid suspension and UPPP, which improved the success rate to approximately 80%.^22,23 This finding further supports the idea that airway blockages occur for different reasons, and a combination of treatments may be necessary to achieve an acceptable result.
Removal of tonsils and adenoids can be effective in treating OSA in children because the adenotonsillar tissues are large and have not yet receded. This procedure is not usually indicated in adults with sleep breathing disorders because the adenoids and tonsils are not large enough to block the airway. 
Nasal surgery such as turbinectomy and septoplasty may reduce AHI, but rarely below 10. Sleep apnea is rarely caused by problems in the nasal cavity alone, so nasal surgery may be used in combination with other surgical procedures in the throat or mouth, if at all.

DISCUSSION

Sleep apnea is an under-diagnosed disorder, and the consequences it has on general health, including cardiovascular health, should be recognized. Diagnosis and treatment of obstructive sleep apnea will improve the quality of life for patients, and dental professionals should play a role in this aspect of their patients’ health. Given the relative lack of public or professional attention given to sleep apnea, it is appropriate that, when indicated, patients be asked about snoring, daytime wakefulness, and other signs and symptoms of OSA. The presence of severe bruxism is also an important warning sign and should trigger further inquiry on the subject. The use of oral appliances to treat sleep apnea deserves consideration, as they are the best treatment option in approximately half of all cases. Furthermore, correcting sleep apnea offers a unique opportunity to collaborate with practitioners in other fields of medicine.

References

Acknowledgment

The author wishes to acknowledge Daniel Shapero for his contribution to this article.

Dr. Singer is in private practice in the areas of Washington, DC, and Alexandria, Va. He is also an assistant clinical professor in the Department of Surgery at George Washington University. He can be reached at (202) 912-9200.

EXTERNAL COMPONENT OF STRESS

Normal function generates considerable stress on teeth and their supporting tissues.1 Since teeth are not rigid structures, they undergo deformation (strain) when a functional load is applied,2,3 and this strain is proportional to the amount of stress. The functional load is influenced by the number of teeth, the type of occlusion, and the occlusal behavior of the patient (ie, premature contacts, parafunctional habits).3 During occlusal loading, the tooth undergoes a lateral or an axial bending called tooth flexure.1,4-11

Figure 1. Occlusal forces are transmitted through the cusp and can become concentrated in the cervical region of the tooth.

The tooth flexure theory states that occlusal forces are transmitted through the cusp(s) and can become concentrated in the cervical region of the tooth4,12 (Figure 1). This theory has been supported by engineering studies7-11 that report that these horizontal loading forces cause a microscopic flexing of the anatomical crown of the tooth. Subsequently, this physiologic bending generates maximal strain in the cervical region of the tooth, with resulting tensile stress concentrations in the cervical region on the side of the tooth from which the force is directed. At the same time, the opposite region of the tooth is under compressive stress. When the direction of the force changes (ie, bruxism), the tooth flexes in the opposite direction, and the stress correspondingly reverses at the cervical region.13
The cyclic tension and compressive stresses that occur in the mouth during chewing or parafunctional habits can reach a fatigue limit and can result in loss of tooth structure or displacement of an adhesive restoration.14-16 In the unrestored tooth the pathological wear (attrition) of tooth substance by these biomechanical loading forces has different morphological characteristics. If the cusp is placed into a state of tension, the resultant cervical defect is wedge shaped; conversely, if the cervical region is subjected to compressive stresses, the defect is more concave or saucer shaped.17-20 In the restored tooth (ie, when a cervical restoration is present), lateral flexure resulting from eccentric forces produces tensile stress at the marginal interface of the restoration, whereas heavy centric forces generate compressive stresses along the marginal interface of the cervical restoration. These repeated flexural forces can cause adhesive failure of cervical composite restorations at the dentin-resin interface, which can result in microleakage or partial or complete debonding of the restoration.21

PREOPERATIVE  CONSIDERATIONS

A successful aesthetic restorative procedure using composite resins for carious and noncarious cervical lesions depends upon a number of preoperative considerations: diagnosis and management, occlusal evaluation, the type of restorative material, shade selection, cavity design, isolation, and gingival health.

Diagnosis and Management

Prior to placement of any cervical restoration, a consideration of all the factors related to loss of tooth structure or displacement of the cervical restoration should be reviewed. This differential diagnosis should help determine the etiology, and information such as age, diet, oral hygiene routine, medical considerations, abnormal oral habits, and occlusal idiosyncrasies should be considered. The information acquired during establishment of the differential diagnosis allows for a methodical approach to preventive and restorative therapy.
The management of carious and noncarious surface lesions begins with identification of the etiology. The objectives of modern management and prevention of tooth surface lesions should be prevention, preservation of hard and soft tissues, and increased longevity of the restoration.22,23 Controlling the advancement of hardtissue destruction can begin with dietary instructions, oral hygiene instructions, home fluoride therapy, brushing with desensitizing dentifrices, discontinuation of poor oral habits, and elimination of the etiology. Management of these lesions may include remineralization through in-office application of fluorides, calcium, and potassium phosphate. Desensitization of these hard surface lesions can be achieved through professional application of potassium oxalate or other tubule-occluding agents, iontophoresis, or application of dentin adhesives. Other management methods include occlusal evaluation and equilibration with occlusal guard fabrication if needed, coronoplasty, or orthodontic treatment.18,19,24

Occlusal Evaluation

Occlusal considerations should be addressed at the treatment planning stage. Prior to administering any restorative treatment, the preoperative occlusal stops and excursive guiding planes should be recorded with articulation paper and transferred to a hand-drawn diagram, then recorded using an intraoral or digital camera, or indicated and reviewed on an articulated diagnostic model. Elimination of interferences in the static and dynamic occlusion to achieve an ideal occlusion with maximum distribution of occlusal load should be performed only after splint therapy. For patients with parafunctional habits (ie, bruxism), the intermittent use of an occlusal splint (a stabilization splint or a localized occlusal interference splint) can be employed to discourage the habit. For other clinical conditions (ie, clenching habits) a period of splint therapy is necessary to reduce or eliminate the effect of compressing the periodontal ligament prior to assessment or equilibration.25 Furthermore, interceptive occlusal equilibration should initially be performed on accurately mounted diagnostic models. Intraoral modifications of the occlusal pattern before any operative procedure can reduce cuspal flexure and cervical stresses that can cause adhesive failure of cervical composite restorations. These preventive measures include equilibration with occlusal guard fabrication, coronoplasty, or orthodontic treatment.18,19,24,25

Restorative Material Selection

Many aesthetic restorative materials are available for the replacement of tooth structure (ie, cervical lesions). These include direct placement of glass ionomers, resin ionomers, compomers, flowable composites, microfill composites, and hybrid composites, or indirect placement of porcelain inlays and laboratory-processed composite resin inlays.19,24,26,27 This discussion will address the selection of restorative materials for direct placement of restorations to treat carious and noncarious cervical lesions.
The initial clinical consideration in the selection of a direct restorative material is the type of cervical lesion, ie, carious or noncarious. The choice of restorative materials for the carious lesion could include a fluoride-releasing material such as glass ionomer, resin ionomer, or compomer. However, when fluoride is not a consideration, composite resin provides an optimal aesthetic result for the carious and noncarious cervical lesion because of the acid-etch technique and the chemical attachment to tooth structure through dentinal bonding.24 Hybrids, micro-fills, and flowable composites are among the options for use in cervical lesions.
Investigations by Heymann, et al on occlusal factors that influence the retention of restorations and the tooth flexure theory indicate that forces are transmitted through the cusp and are concentrated in the cervical region of the tooth.4,12 These data influence the type of restorative material that is selected for such lesions. Composite resins with a low modulus of elasticity can absorb this energy that is transferred from the occlusal surface, reducing transmission to the dentin-restorative interface.28 The microfill and flowable composite resins have a lower modulus of elasticity than do hybrid or conventional composite resins.24 Additionally, some dentin adhesives can provide an elastic intermediate layer between the restorative material and the cavosurface to absorb this flexural deformation of the tooth.29

Shade Selection

Shade selection should be accomplished prior to placement of the dental dam to prevent improper selection as a result of dehydration and resultant elevated color value.30 The use of color-corrected daylight source illumination (5,500ºK) is necessary for proper color registration.31,32 However, to obtain an acceptable shade interpretation it is advisable for the viewers (technician, clinician, and assistant) to observe the color-matching under various lighting conditions—daylight, color-corrected, fluorescent light, and dim light.31-34 A shade map or restorative recipe can be used to diagram the existing colors of composite resin and modifiers used when making the mock-up. The composite mock-up is a preoperative diagnostic and evaluation tool. Composite resin is applied directly to the tooth surface without an adhesive or anesthesia to simulate the final result. This technique establishes the parameters for contours, texture, and orientation of composite shades. It provides the patient and clinician with immediate visualization of the final dimensions and color-matching before the procedure, which can result in immediate treatment decisions.
Because of the variety of colors and their orientation within natural teeth, appropriate shade selection for composite restorations remains a challenge. As mentioned in Part 1 of this article, a custom-fabricated shade system was utilized that is synchronized with the same polymerized restorative material as the composite system that is being matched, which allows the clinician to compare the actual polymerized composite to the natural tooth color for a more predictable and accurate aesthetic color match.

Cavity Design

Composite resin systems depend upon the use of adhesive preparation designs that are conservative, and require meticulous adherence to proper adhesive techniques.35-38 Consideration should be given to the following: tooth type, location in the arch, size and type of the carious lesion, whether treatment involves a carious or noncarious unrestored tooth or replacement of a restoration, and the relationship between occlusal function and preparation boundaries. Also, the type of restorative technique, the amount and status of the remaining tooth structure, resistance to microleakage through groove placement, mechanical forces, presence of defects, and the parameters for extension of the preparation to the aesthetic zone should be re-viewed.3,37,39

Isolation

Fundamental restorative principles require maintaining sound tooth structure, achieving a sterile, gap-free hybrid layer, and eliminating micro-leakage by securing a relatively stress-free tooth-restoration interface.23 Adhesive biomaterials are technique-sensitive and require moisture control and meticulous attention to the adhesive protocol. For optimal bonded composite restorations, moisture control should be performed throughout the adhesive procedure, which requires adequate isolation of the operating field with use of a dental dam.40
A restorative material properly bonded to the enamel and dentin substrate will reduce marginal contraction gaps, microleakage, marginal staining, and caries recurrence, and improve retention, reinforce tooth structure, and dissipate and reduce functional stresses across its interface throughout the entire tooth while improving aesthetics and resistance to wear.41-45

Gingival Health

Mucogingival health is also a critical component of a successful restorative result. Gingival inflammation due to plaque retention can result in alterations in gingival form and contour. Consequently, inaccurate assessment of the margin relationship of the restorations to the gingival architecture can result in a compromised restorative outcome. Therefore, periodontal health should be present prior to the initiation of any restorative procedure that requires the restoration to be in contact with the periodontium or that influences plaque control. Since gingival health is established prior to any operative procedure, it is possible to manipulate soft tissues for adequate preparation design and material placement without causing bleed-
ing or traumatic injury.46
The preoperative evaluation for the patient treated in the following case report included all of the aforementioned considerations. This case will illustrate the methods for managing and reducing the internal and external components of stress in class V composite restorations using a low-shrinkage nano-particle hybrid composite resin (Synergy D6 [Coltène/Whaledent]).

A CLASS V COMPOSITE RESTORATION

Clinical Procedure

Figure 2. Preoperative view of saucer-shaped noncarious cervical lesions on the maxillary left cuspid and first bicuspid teeth.	Figure 3. An equilibration was performed to eliminate the premature occlusal contacts.

This case presentation illustrates cervical lesions that were noncarious and caused by deflective occlusal contacts.19,47 As mentioned previously, these biomechanical loading forces cause stress concentrations in the cervical region of the tooth during tooth contact, which can result in loss of tooth structure. Many patients with these lesions present to the dentist because of sensitivity to brushing and temperature changes, and may require an anesthetic prior to the procedure.
The patient, a 42-year-old male, presented with sensitivity of the maxillary left cuspid and first bicuspid teeth. Clinical examination revealed saucer-shaped cervical defects with no caries, plaque, gingival recession, or inflammation (Figure 2). Wear patterns were present on the occlusal surfaces of these teeth. After review of the patient’s medical and dental history and considering the examination findings, the diagnosis was abrasive-abfraction lesions caused by compressive stress and toothbrush abrasion.13
Upon stabilization with occlusal splint therapy and a careful mock equilibration on accurately mounted diagnostic models, an occlusal equilibration was performed to eliminate interferences in the static and dynamic occlusion and provide maximal distribution of the occlusal load25 (Figure 3). A preoperative selection of composite resins, tints, and modifiers with shade and orientation was recorded.

Figure 4. A retraction cord was placed to gain adequate access to the gingival margin.

Once anesthesia was administered, the teeth were isolated with a dental dam to achieve adequate field control and to protect against contamination. A modified technique was used to create an elongated opening that allowed placement of the dam over the retainer.48,49 To gain adequate access to the gingival margin, a plain, knitted retraction cord (Ultrapak No. 00 [Ultradent Products]) was placed using a Fischer’s Ultra-pak Packer No. 170 (Ultra-dent Products; Figure 4). To effect an aesthetic result, a chamfer 0.3 mm in depth was placed along the occlusal margin with a long tapered diamond (No. 6850 [Brasseler USA]). A scalloped bevel was developed 0.5 mm in the enamel to interrupt the straight line of the chamfer (Figure 5). The bevel was placed on enamel to reduce the potential for microleakage. Several methods can be used to increase mechanical retention of adhesive restorations in certain clinical situations (ie, sclerotic dentin), including using a slow-speed bur or air abrasion to roughen the dentin surface. This allows better resin penetration of the sclerotic dentin. Placement of grooves will also improve retention. Although not required for successful adhesion, grooves provide resistance to the internal and external components of  stress—polymerization shrinkage and tooth flexure.50

Figure 6. The preparation was scrubbed with a slurry mixture of disinfectant and pumice.	Figure 7. The preparations were etched with a 35% phosphoric acid, rinsed, and gently air-dried.

The preparation was scrubbed with a slurry mixture of disinfectant and pumice (Consepsis [Ultradent Products]; Figure 6). The total-etch technique was used to minimize the potential for microleakage and enhance bond strength to dentin and enamel.51-53 The preparation was etched for 15 seconds with 35% phosphoric acid (Etchant Gel S [Coltène/Whaledent]; Figure 7), rinsed for 5 seconds, and gently air-dried for 5 seconds. A single-component adhesive (One Coat Bond [Coltène/Whaledent]) was applied with a disposable applicator for 20 seconds with a continuous motion, reapplying every 5 seconds. Any excess was removed with the applicator, and the agent was air-thinned and then light-cured for 30 seconds (Figure 8). Although a small amount of excess adhesive can be applied over the margins to improve sealing, this excess should be removed during finishing procedures. Furthermore, the use of an adhesive bonding system as a stress-breaking liner between the restorative composite resin and tooth cavosurface has been mentioned previously.29
The preparation was filled incrementally using an A1/B1 shaded hybrid composite (Synergy D6) based on the preoperative shade map. Because the microhybrid composite resins have refractive properties and a variety of color selections that are similar to that of dentin, they imitate the natural tooth structure extremely well.

The initial layer, consisting of 1 mm of dentin-shaded composite resin, was applied to the occlusal one half of the preparation and contoured with a long bladed composite instrument (TNCVIPC [Hu-Friedy]) to ensure complete adaptation to the underlying resin and tooth structure (Figure 9). Each layer was smoothed with an artist’s brush to prevent surface ir-regularities (Figure 10); a thin layer of resin was applied to that layer and cured for the purpose of creating a “light diffusion layer,” which yields an illusion of depth for restorations of limited thickness. This layer of high translucency causes an internal diffusion of light and controls the luminosity within the internal aspects of the restoration. A similar proteinaceous layer (a highly concentrated protein matrix), which separates the dentin and enamel, exists in natural teeth;54 ceramists call this the “glass layer.”

Figure 9. The dentin layer, an A1/B1 shaded hybrid composite, was applied to the occlusal half of the preparation and contoured with a long bladed composite instrument.	Figure 10. Each incremental layer was smoothed with a sable brush to prevent surface irregularities.
Figure 11. A second layer of hybrid composite was placed in the gingival half of the preparation and contoured.	Figure 12. A universal enamel shaded hybrid composite was placed on the cervical region of the tooth and smoothed with a sable brush to encase the underlying dentin matrix.

Each increment was polymerized with a low-intensity light-curing unit for 20 seconds, which allows placement of subsequent increments without deforming the underlying composite layer. The second dentin-shaded layer was placed in the gingival half of the preparation, and the process was repeated (Figure 11). Incrementally filling the cavity preparation in sequence, first the occlusal segment and then the gingival segment, promotes stress reduction by reducing the influence of the C-factor at the restorative interface. In addition, first placing the occlusal segment with higher bond strength to enamel may reduce the potential for microgaping at the gingival margin. To prevent overbuilding of the artificial dentin layer, it is imperative to monitor the composite from the incisal aspect to provide adequate space for the final artificial enamel layer and allow for ideal anatomical contour.
To recreate the natural translucency of enamel, a universal enamel shaded hybrid composite (Synergy D6) was used to achieve proper color value. The resin was rolled into a ball and placed on the cervical region of the tooth, sculpted with a long bladed composite instrument, and smoothed with a sable brush to obtain an anatomically correct emergence profile that encased the underlying matrix cervicoincisally and mesio-distally (Figure 12). The process of carefully shaping the composite resin to those confines before curing facilitates the establishment of anatomical morphology and minimizes the finishing protocol. One study has determined that a reduction in finishing results in less damage to the composite and improved wear and clinical performance.55 A thin coating of glycerin was applied to the surface and polymerized for a 2-minute post-cure, ensuring complete polymerization of the composite resin at the margins.

Finishing and Polishing

Ensuring gingival health through proper anatomic contours, marginal integrity, and surface texture is an important consideration for restoration of both carious and noncarious lesions. An optimally finished aesthetic restoration should provide a smooth surface that will prevent plaque accumulation and resist stain, and possess ideal contours and emergence profile for improved tissue compatibility. Additionally, it should be in harmony with the gingival tissues, have proper anatomical form for ideal occlusion, shade coordination to the surrounding dentition, symmetrical surface texture to adjacent or opposing natural teeth, ideal marginal adaptation and integrity, longevity, and aesthetics.56-58
Removal or trimming of composite resin can be achieved in 3 sequential steps: contouring, fine finishing, and polishing. Contouring involves the gross reduction of the composite restoration to obtain the desired form and shape as determined by the parameters of function and aesthetics.59 Fine finishing comprises the delicate and precise finishing of the margins, removing surface defects and scratches, and developing a smoother surface.57 Polishing consists of reducing the roughness and scratches produced during the finishing procedure.60
The objective of polishing is to reduce the surface irregularities so that the distance between the scratches is less than the wavelength of visible light (approximately 0.5 µm). This will make the surface as reflective as enamel.61 A surface appears smooth when its roughness is significantly less than 1 µm.62,63 These steps should be performed in sequence using abrasives and various polishing devices. The principle is similar to metal polishing, in which the sequence of abrasives progresses from the coarsest to the finest.64 The abrasiveness of one particle or material depends on its hardness.65 Hardness is defined as the resistance to permanent indentation or penetration.60 In order for a composite finishing and polishing system to be effective, the cutting particles (abrasives) must be harder than the filler component of the composite.66 Accordingly, the effectiveness of the finishing and polishing process depends upon the type of composite resin utilized.67-73
Newer formulations of small-particle hybrids and microhybrids have altered filler components, specifically finer filler size, shape, orientation, and concentration, which improve their physical and mechanical characteristics and allow the resin composite to be polished to a high degree.62 The variation in hardness between the inorganic filler and the matrix can result in surface roughness, since these 2 components do not abrade uniformly.62,74 Accordingly, it is imperative that the surface gloss between the restorative material and tooth interface is similar, because the gloss can influence color perception and shade-matching of the restoration and tooth
surface.62,75

Figure 13. The anatomic contour was achieved with a No. 30 fluted, needle-shaped finishing bur.	Figure 14. The gingival margin was retracted with a Zekrya instrument, and the margin was finished using a No. 30 fluted, short, tapered finishing bur.

The initial contouring was performed with a series of finishing burs to replicate the natural form of the tooth. For finishing the labial surface, a long, needle-shaped finishing bur was used to develop the proper anatomical contours of the facial aspect of the anterior tooth. To replicate natural form and texture, Nos. 16 and 30 fluted, needle-shaped finishing burs (ET6 [Brasseler USA]) were used dry with light pressure to prevent heat buildup (Figure 13). This dry finishing allows the clinician to visualize the margins and contours relative to the adjacent tooth. A smooth surface can be achieved by sequentially increasing the number of flutes (Nos. 16 and 30). The gingival contouring was accomplished with a short, tapered, straight-edge finishing bur (ET3 [Brasseler USA]), which conforms to the straight emergence profile as the tooth emerges from the gingival sulcus (Figure 14). It is important to use a dry protocol and retract the gingiva with an 8A instrument or Zekrya (Zenith Dental/DMG), closely observing tooth structure and the gingival margin. It is important not to overheat the resin by using excessive pressure. It is also imperative not to ditch or scar the cementum at the gingival margin.
After the initial finishing procedure, the margins and surface defects were sealed. The restoration and all margins were re-etched for 15 seconds with a 35% orthophosphoric acid (Etchant Gel S), rinsed for 5 seconds, and dried. A layer of composite surface sealant (Fortify Plus [Bisco]) was applied over the margins and the restoration. This will prevent leakage and seal any microfractures or microscopic porosities in the material that may have formed during finishing. The use of surface sealant has been shown to reduce the wear rate of posterior composite resins,76 improve resistance to interfacial staining,77 and decrease micro-leakage around class V composite resins.77-79 Any excess resin can be removed with a No. 12 scalpel, and the retraction cord is removed to inspect for overhangs.

Figure 15. Initial polishing was accomplished with rubber hollow cups, which eliminate any surface defects or rough areas.	Figure 16. To impart a high luster, a loose abrasive aluminum oxide polishing paste was applied with a synthetic foam cup and a small amount of water.

Fine finishing of the facial and gingival region was performed with pre-polish and high-shine rubber points and rubber hollow cups (Flexi-Points/FlexiCups  [Cosmedent]), which are composed of aluminum oxide particles and silicone that eliminate surface defects (Figure 15 ). The impregnated cup follows the contour of the gingival neck and reaches into the sulcus to smooth any rough areas. To impart a high luster or surface reflectivity on the tooth and restoration while maintaining the existing texture and surface anatomy, the final polishing was accomplished with loose abrasive polishing paste and a synthetic foam cup (Enhance cup [DENTSPLY]) applied at conventional speed (Figure 16). This type of loose abrasive paste contains aluminum oxide or diamond particles dispersed in a water-soluble vehicle such as glycerin, and allows the anatomical details to be maintained while imparting an enamel-like appearance to the restored tooth. The incremental use of water with these loose, aluminum oxide abrasives enhances their effectiveness. Loose abrasives with aluminum oxide particles include Prisma Gloss/Prisma   Gloss ExtraFine (DENTSPLY/Caulk), CompoSite (Shofu), and Enamelize (Cosmedent).
If diamond abrasive pastes are used, they should be kept as dry as possible because their effectiveness decreases when diluted with saliva. Loose abrasives with diamond particles include Diamond Polish Paste (Ultradent Products) and Ceroshine diamond paste (Brasseler USA).

The postoperative result achieved reflects the result of meticulous use of restorative adhesive concepts (adhesive preparation design and selective bonding protocol) with a small-particle hybrid composite, and proper occlusal considerations and management for the successful rehabilitation of the dento-gingival complex (Figure 17). The completed restoration harmoniously integrated with the surrounding tissues, and the patient no longer experienced sensitivity.

Conclusion

The tooth-restorative interface is constantly subjected to polymerization shrinkage and occlusal stresses. Identifying the source of stress and understanding its manifestations in regard to composite resin restorations have led to clinical techniques that prevent and/or manage these stresses. Achieving success with composite resin restorations requires a relatively stress-free tooth-restoration in-terface. This 2-part article has defined the necessary considerations, stress reduction methods, and operative techniques to attain predictable clinical success with composite resins.

References

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25. Davies SJ, Gray RJ, Qualtrough AJ. Management of tooth surface loss. Br Dent J. 2002;192:11-23.
26. Mount GJ. Restorations of eroded areas. J Am Dent Assoc. 1990;120:31-35.
27. Miller MB. Restoring Class V lesions, Part 1: carious lesions. Pract Periodontics Aesthet Dent. 1997;9:441-442.
28. Leinfelder KF. Restoration of abfracted lesions. Compendium. 1994;15:1396-1400.
29. Cardoso PE, Placido E, Francci CE, et al. Microleakage of Class V resin-based composite restorations using five simplified adhesive systems. Am J Dent. 1999;12:291-294.
30. Fahl N Jr, Denehy GE, Jackson RD. Protocol for predictable restoration of anterior teeth with composite resins. Pract Periodontics Aesthet Dent. 1995;7:13-21.
31. Dietschi D. Free-hand composite resin restorations: a key to anterior aesthetics. Pract Periodontics Aesthet Dent. 1995;7:15-25.
32. Touati B, Miara P, Nathanson D. Color and light transmission. In: Esthetic Dentistry and Ceramic Restorations. London, UK: Martin Dunitz; 1999:39-60.
33. O’Keefe KL, Strickler ER, Kerrin HK. Color and shade matching: the weak link in esthetic dentistry. Compendium. 1990;11:116-120.
34. Springstead MC, Rogers WA, Cline NV. The preliminary prosthetic consultation form. Trends Tech Contemp Dent Lab. 1992;9:59-63.
35.Lutz F. State of the art of tooth-colored restoratives. Oper Dent. 1996;21:237-248.
36. Lutz FU, Krejci I, Oddera M. Advanced adhesive restorations: the post-amalgam age. Pract Periodontics Aesthet Dent. 1996;8:385-394.
37. Dietschi D, Spreafico R. Adhesive Metal-Free Restorations: Current Concepts for the Esthetic Treatment of Posterior Teeth. Berlin, Germany: Quintessence Publishing; 1999.
38. Quellet D. Considerations and techniques for multiple bulk-fill direct posterior composites. Compend Contin Educ Dent. 1995;16:1212-1224.
39. Wilson NH, Dunne SM, Gainsford ID. Current materials and techniques for direct restorations in posterior teeth. Part 2: resin composite systems. Int Dent J. 1997;47:185-193.
40. Magne P, Dietschi D, Holz J. Esthetic restorations for posterior teeth: practical and clinical considerations. Int J Periodontics Restorative Dent. 1996;16:104-119.
41. Goracci G, Mori G. Esthetic and functional reproduction of occlusal morphology with composite resins. Compend Contin Educ Dent. 1999;20:643-648.
42. Touati B. Bonded ceramic restorations: achieving predictability. Pract Periodontics Aesthet Dent. 1995;7:33-37.
43. Santos J, Bianchi J. Restoration of severely damaged teeth with resin bonding systems: case reports. Quintessence Int. 1991;22:611-615.
44. Van Meerbeek B, Vanherle G, Lambrechts P, et al. Dentin- and enamel-bonding agents. Curr Opin Dent. 1992;2:117-127.
45. Eakle WS. Fracture resistance of teeth restored with class II bonded composite resin. J Dent Res. 1986;65:149-153.
46. Ramfjord SP. Aesthetics, periodontology, and restorative dentistry. Quintessence Int. 1985;16:581-588.
47. Brackett WW. The etiology and treatment of cervical erosion. J Tenn Dent Assoc. 1994;74:14-18.
48. Croll TP. Alternative methods for use of the rubber dam. Quintessence Int. 1985;16:387-392.
49. Liebenberg WH. General field isolation and the cementation of indirect restorations: part I. J Dent Assoc S Afr. 1994;49:349-353.
50. Montiero S Jr, Sigurjons H, Swartz ML, et al. Evaluation of materials and techniques for restoration of erosion areas. J Prosthet Dent. 1986;55:434-442.
51. Nakabayashi N, Nakamura M, Yasuda N. Hybrid layer as a dentin-bonding mechanism. J Esthet Dent. 1991;
3:133-138.
52. Kanca J III. Improving bond strength through acid etching of dentin and bonding to wet dentin surfaces. J Am Dent Assoc. 1992;123:35-43.
53. Kanca J III. Resin bonding to wet substrate. II. Bonding to enamel. Quintessence Int. 1992;23:625-627.
54. Vanini L. Light and color in anterior composite restorations. Pract Periodontics Aesthet Dent. 1996;8:673-682.
55. Duke ES. Direct posterior composites. J Indiana Dent Assoc. 1993;72:35-39.
56. Yap AU, Ang HQ, Chong KC. Influence of finishing time on marginal sealing ability of new generation composite bonding systems. J Oral Rehabil. 1998;25:871-876.
57. Jefferies SR. The art and science of abrasive finishing and polishing in restorative dentistry. Dent Clin North Am. 1998;42:613-627.
58. Ward MT, Tate WH, Powers JM. Surface roughness of opalescent porcelains after polishing. Oper Dent. 1995;20:106-110.
59. Lutz F, Setcos JC, Phillips RW. New finishing instruments for composite resins. J Am Dent Assoc. 1983;107:575-580.
60. Yap AU, Sau CW, Lye KW. Effects of finishing/polishing time on surface characteristics of tooth-coloured restoratives. J Oral Rehabil. 1998;
25:456-461.
61. Van Noort R. Controversial aspects of composite resin restorative materials. Br Dent J. 1983;155:380-385.
62. Chung KH. Effects of finishing and polishing procedures on the surface texture of resin composites. Dent Mater. 1994;10:325-330.
63. Jung M. Finishing and polishing of a hybrid composite and a heat-pressed glass ceramic. Oper Dent. 2002;27:175-183.
64. Hondrum SO, Fernandez R Jr. Contouring, finishing, and polishing class 5 restorative materials. Oper Dent. 1997;22(1):30-36.
65. Mitchell CA, Pintado MR, Douglas WH. Iatrogenic tooth abrasion comparisons among composite materials and finishing techniques. J Prosthet Dent. 2002;88:320-328.
66. Chandler HH, Bowen RL, Paffenbarg-er GC. Method for finishing composite restorative materials. J Am Dent Assoc. 1971;83:344-348.
67. Tjan AH, Chan CA. The polishability of posterior composites. J Prosthet Dent. 1989;61:138-146.
68. Boghosian AA, Randolph RG, Jekkals VJ. Rotary instrument finishing of microfilled and small-particle hybrid composite resins. J Am Dent Assoc. 1987;115:299-301.
69. Reis AF, Giannini M, Lovadino JR, et al. Effects of various finishing systems on the surface roughness and staining susceptibility of packable composite resins. Dent Mater. 2003;19:12-18.
70. Schmidseder J. Color Atlas of Dental Medicine: Aesthetic Dentistry. New York, NY: Thieme Medical Publishers; 2000.
71. Dietschi D, Campanile G, Holz J, et al. Comparison of the color stability of ten new-generation composites: an in vitro study. Dent Mater. 1994;10:353-362.
72. Christensen RP, Christensen GJ. Comparison of instruments and commercial pastes used for finishing and polishing composite resin. Gen Dent. 1981;29:40-45.
73. Duke ES. Finishing and polishing techniques for composite resins. Compend Contin Educ Dent. 2001;22:392-396.
74. Chen RC, Chan DC, Chan KC. A quantitative study of finishing and polishing techniques for a composite. J Prosthet Dent. 1988;59:292-297.
75. Stanford WB, Fan PL, Wozniak WT, et al. Effect of finishing on color and gloss of composites with different fillers. J Am Dent Assoc. 1985;110:211-213.
76. Dickinson GL, Leinfelder KF. Assessing the long-term effect of a surface penetrating sealant. J Am Dent Assoc. 1993;124:68-72.
77. Kemp-Scholte CM, Davidson CL. Marginal sealing of curing contraction gaps in class V composite resin restorations. J Dent Res. 1988;67:841-845.
78. Estafan D, Dussetschleger FL, Miuo LE, et al. Class V lesions restored with flowable composite and added surface sealing resin. Gen Dent. 2000;48:78-80.
79. Barone-Smith CE, Dickens SH. Effect of surface sealing on the microleakage of bonded restorations. J Dent Res. 1999;155:Abstract 394.

Dr. Terry received his DDS from the University of Texas Health Science Center Dental Branch at Houston in 1978. He has published more than 230 articles on various topics in aesthetic dentistry in numerous languages and authored the textbook Natural Aesthetics with Composite Resin. He is an assistant professor, Department of Restorative Dentistry and Biomaterials, at the University of Texas Health Science Center Dental Branch at Houston. Dr. Terry maintains a private practice in Houston emphasizing aesthetic and restorative dentistry. He can be reached at (281) 481-3483.

Dr. Leinfelder earned his doctor of dental surgery and master of science (dental materials) degrees from Marquette University. After serving for 8 years on the faculty at Marquette, he joined the faculty at the University of North Carolina School of Dentistry, where he attained the rank of professor and director of biomaterials clinical research in the Dental Research Center. In 1983, he joined the School of Dentistry at the University of Alabama and held the Joseph Volker Chair. He also served as chairman of the Department of Biomaterials until 1994. Presently he holds positions at both universities: adjunct professor at the University of North Carolina and professor emeritus at the University of Alabama. He is the recipient of the Dr. George Hollenbeck award (1995) as well as the Norton N. Ross award for outstanding clinical research (1997), and the American College of Prosthodontists Distinguished Lecturer Award (1998). He has served as associate editor of the Journal of the American Dental Association. He can be reached at (919) 370-9168.

Continuing Education Test No. 85.2

After reading this article, the individual will learn:

• tooth flexure theory and clinical manifestations of occlusal forces at the cervical
  region of the tooth, and
• methods for prevention, management, and treatment of carious and noncarious
  class V lesions.

1. During occlusal loading, the tooth under-goes a lateral or an axial bending called tooth flexure. This generates minimal strain in the cervical region, resulting in tensile stress concentrations in the cervical region on the opposite side of the tooth from which the force is directed.

a. The first statement is correct and the second statement is incorrect.
b. Both statements are correct.
c. The first statement is incorrect and the second statement is correct.
d. Both statements are incorrect.

2. Repeated flexural forces can cause adhesive failure of cervical composite restorations at the dentin-resin interface, which can result in ____.

a. complete debonding of the restoration
b. microleakage at the restorative interface
c. partial debonding of the restoration
d. all of the above

3. The objectives of modern management and prevention of tooth surface lesions include ____.

a. a shorter time between replacement of restorations
b. preservation of hard and soft tissues
c. prevention of hard- and soft-tissue destruction
d. both b and c

4.Composite resins with a high modulus of elasticity can absorb energy transferred from the occlusal surface, increasing transmission to the dentin-restorative interface. Microfill and flowable resins have a higher modulus of elasticity than do hybrid or conventional resins.

a. The first statement is correct and the second statement is incorrect.
b. Both statements are correct.
c. The first statement is incorrect and the second statement is correct.
d. Both statements are incorrect.

5. Restorative principles require maintaining sound tooth structure, a sterile, gap-free hybrid layer, and eliminating microleakage by securing a relatively stress-free tooth-restoration interface.  Adhesive biomaterials are technique sensitive and require moisture control and meticulous attention to adhesive protocol.

a. The first statement is correct and the second statement is incorrect.
b. Both statements are correct.
c. The first statement is incorrect and the second statement is correct.
d. Both statements are incorrect.

6.Which method does NOT increase mechanical retention of adhesive restorations when clinical conditions such as sclerotic dentin exist?

a. placement of grooves
b. roughening the dentin surface with a slow-speed bur
c. use of additional coats of adhesive resin
d. roughening the dentin surface with air abrasion

7. An optimally finished aesthetic restoration should provide ____.

a. proper anatomical form for ideal occlusion
b. ideal contours and emergence profile for improved tissue compatibility
c. a smooth surface that will prevent plaque accumulation and resist stain
d. all of the above

8. Hardness is defined as the resistance to permanent indentation or penetration. Effective composite finishing/polishing requires the cutting particles (abrasives) to be softer than the filler component of the composite.

a. The first statement is correct and the second statement is incorrect.
b. Both statements are correct.
c. The first statement is incorrect and the second statement is correct.
d. Both statements are incorrect.

To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 85.2), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).

Stresses At The Restorative-Tooth Interface

The integrity of the bond and marginal adaptation to the tooth structure are critical for clinical success of composite restorations.8 The tooth-restorative interface is constantly subjected to forces during placement of composite resins and during normal function. Before a restoration is subjected to functional loading and thermal strain there is an initial interfacial stress during polymerization of the restorative material and adhesion to tooth structure.9 During a restorative procedure using composite resin, the polymerization reaction of the resin matrix phase could compromise dimensional stability.4 Therefore, a thorough understanding of the complex interplay between polymerization shrinkage and adhesion is necessary. The conversion of the monomer molecules into a polymer network is accompanied by a close packing of the molecules, leading to bulk contraction.10 Alternatively, when a curing material is bonded on all sides to a rigid structure, bulk contraction cannot occur, and shrinkage must be compensated for by increased stress, flexure, or gap formation at the adhesive interface.4
Polymerization shrinkage or curing contraction is the volumetric decrease a composite system undergoes because of the curing process.11 The cross-linking of resin monomers into polymers is responsible for an unconstrained volumetric shrinkage of 2% to 5%.12 During the polymerization reaction, the visco-elastic behavior of the composite changes from viscous to viscous-elastic to elastic. While stress does not exist in the viscous stage, in the visco-elastic stage stresses can partly be relieved by flow and elastic strain.13

Figure 1. The factors influencing polymerization shrinkage.

The moment at which the material can no longer provide viscous flow to keep pace with the curing contraction is referred to as the gel point.4 When the composite material develops an elastic modulus, a volumetric polymerization contraction results in shrinkage stress. Shrinkage stresses are transferred to the surrounding tooth structure, because it serves to restrict the volumetric changes.13 The uncompensated forces may exceed the bond strength of the tooth-restoration interface, resulting in gap formation from loss of adhesion.14 The factors that influence polymerization shrinkage include the following: type of resin,11 filler content of the composite,11,15,16 elastic modulus of the material,16 curing characteristics,17 water sorption,18-20 cavity configuration,5 and the intensity of the light used to polymerize the composite13,21,22 (Figure 1). By un-derstanding this complex relationship between polymerization shrinkage and adhesion, the clinician can select application techniques and restorative materials that prevent gap formation at the time of placement of each restoration.
In addition, the restorative interface is constantly subjected to functional loading after placement of the composite restoration. The cervical region of teeth may experience excessive eccentric loading from parafunctional habits such as clenching and bruxism.23,24 These repeated flexural forces can cause adhesive failure of cervical composite restorations at the dentin-resin interface, which can result in microleakage or partial or complete debonding of the restoration.25 Interceptive occlusal equilibration and fabrication of an occlusal guard prior to restorative treatment, in conjunction with specific incremental placement techniques, can provide restorative solutions.

Managing Stress On Composite Resin Restorations

Methods for preventing the undesirable effects of polymerization shrinkage include the use of a lower modulus composite resin to compensate for curing contraction stress, controlling polymerization contraction forces by the cavity design, using internal cavity liners, controlling the intensity of curing, and layering of small increments of a low-shrinking composite resin.17,26,27 Preoperative solutions for controlling excessive eccentric loading include interceptive occlusal equilibration and occlusal guard therapy prior to restorative treatment. The following sequence will illustrate the methods for managing and reducing polymerization shrinkage in a class I composite restoration.

Developing A Class I Composite Restoration

Figure 2. A class I cavity preparation has the highest C-factor and the greatest internal stress.	Figure 3. Preoperative occlusal view of defective amalgam restorations with recurrent caries on the mandibular right first and second molars.

The cavity configuration (C-factor) has a significant effect on the magnitude of shrinkage stresses that results from polymerization. The C-factor is defined as the ratio between the bonded and free surfaces of the restoration.5 The class I cavity has the highest C-factor (ie, class I is 5:1, class II is 4:2) and the greatest internal stress (Figure 2).
In this case, a 63-year-old male dentist presented with defective amalgam restorations on the mandibular right first and second molars. The existing restorations had open margins with recurrent caries (Figure 3). After thorough examination and assessment, the patient expressed interest in replacement of the existing restorations with tooth-colored restorations.

Restorative Procedure

Preoperative Considerations
Preoperative considerations during the diagnostic and treatment planning phase are essential for the development of functional and aesthetic restorations. Three preoperative clinical protocols should be considered before any restorative treatment is initiated.
The first protocol is to select the appropriate restorative material for the procedure. Traditionally, the dilemma associated with conventional hybrid materials for these large restorations has focused on polymerization shrinkage. As mentioned, the class I restoration exhibits the highest C-factor and the greatest internal stress, and therefore a low-shrinkage nanoparticle hy brid composite resin (Synergy D6  [Coltène/Whaledent]) was selected. In addition, this material provides radiopacity, increased filler loading compared to older formulations of composite resins, and ease of placement without slumping.
 The second protocol is to define the desired color by selecting composite resins for the “artificial dentin” and “artificial enamel” shades and orientation. A new shade system developed by Coltène/Whaledent was utilized in this case. This custom fabricated shade system is synchronized with the same polymerized restorative material as the composite system that is being matched, which allows the clinician to compare the actual polymerized composite to the natural tooth color for a more predictable and accurate color match. Most composite resin shade systems are designed to yield tooth color and translucency with a single material (ie, p orcelain or composite). This system is based on the concept that most of the tooth color is due to the dentin, and thus by gr ouping Vita shades of similar hue, chroma, and value, the artificial dentin can realistically replicate the optical properties of the natural tooth. The simplicity of 5 duo dentin shades (ie, A1/B1, A2/B2, A3/D3) with the combination of only 2 e namel shades (ie, Enamel Universal and Enam el White Opalescent) facilitates shade determination yet provides a wid e variety of hues, translucencies, fluorescences, and opalescents.
Shade selection should b e accomplished prior to placement of the dental dam to prevent improper color matching as a result of tooth dehydration, which causes elevated values.28 When teeth dehydrate, air replaces water between the enamel rods and changes the refractive index, which makes the enamel appear opaque and white.29
The third protocol is to establish the occlusal confines, where the preoperative contacts and excursive guiding movements are recorded with articulation paper. This information is then transferred to a hand-drawn diagram of the occlusal surface, recorded via an intraoral or digital camera, or marked on a stone model. The initial registration is valuable for preparation design, when de termining placement of centric stops beyond or within the confines of the restoration, and to minimize finishing procedures.30 In addition, since anatomical

Isolation and Preparation Design

Figure 4. A caries-disclosing solution was applied to facilitate detection and identification of the carious tissue.	Figure 5. The carious tooth structure was removed with a No. 6 round bur.
Figure 6. Occlusal view of completed preparations.	Figure 7. The preparations are cleansed with 2% chlorhexidine solution.
Figure 8. The total-etch technique minimizes the potential for microleakage and enhances bond strength to dentin and enamel.	Figure 9. Following surface preparation, a single-component adhesive was applied to the preparations.

Once anesthesia is administered, the treatment site is isolated with a dental dam to achieve adequate field control and protect against contamination.31,32 Upon removal of the existing amalgam restoration a caries-disclosing solution (Seek/Sable Seek  [Ultradent Products]) aids in the detection and identification of carious tissue and serves as a guide for its removal33 (Figure 4). The carious dentin was removed with a slow-speed carbide round bur No. 6 (Midwest) and spoon excavators (Figure 5). The occlusal outline is then extended to include carious enamel, provide access to carious dentin, remove any residual amalgam staining, and provide access for the application of restorative materials (Figure 6). Healthy tooth structure should only be removed when the occlusal outline requires extension to a point within or beyond the functional stops. The adhesive preparation design requires maximum preservation of remaining tooth structure, and there is no extension for prevention. The preparation is limited to what is needed for access to the lesion or defect, since composite requires less volume to resist clinical fracture than does amalgam.34,35 To allow for a better resin adaptation, all internal line angles should be rounded and cavity walls should be smooth.36 The occlusal cavosurface margin should not be beveled; this increases the width of the preparation and may infringe on the centric holding area, increasing the wear rate of the restoration.37 Beveling should be restricted to the gingival and proximal margins where enamel is present. This increases the potential for bonding as well as fracture resistance by increasing the bulk of the restoration. This approach also increases the bonding surface area and decreases microleakage by exposing the enamel rods for etching.38
The preparations are completed with a finishing diamond and cleaned with a 2% chlorhexidine solution (Consepsis [Ultradent Products]), rinsed, and lightly air-dried (Figure 7). The total-etch technique is used to minimize the potential for microleakage and enhance bond strength to dentin and enamel.39-41 The preparation is etched for 15 seconds with 35% phosphoric acid (Etchant Gel S [Coltène/Whaledent];  Figure 8), rinsed for 5 seconds, and gently air-dried for 5 seconds. A single-component adhesive (One Coat Bond [Coltène/Whaledent]) is then applied with a disposable applicator for 20 seconds with a continuous motion, reapplying every 5 seconds (Figure 9). Any excess was removed with the applicator, and the adhesive was light-cured for 30 seconds. Although a small amount of excess adhesive can be applied over the margins to improve sealing, this excess should be removed during finishing procedures.

The Cavity Liner

Figure 10. To ensure optimal internal adaptation, a small increment of flowable composite is applied to the pulpal floor and light-cured for 40 seconds.

The use of a flowable composite as a stress-absorbing lining material between the adhesive system and the restorative composite resin has been suggested for large restorations.42 The combination of flowables and viscous composite ensures a more intimate contact with the dentin bonding agent because of the lower viscosity, and it has resulted in enhanced internal adaptation.43 Because of a low modulus of elasticity, these composites act as an elastomer and buffer the stress associated with polymerization shrinkage. Theoretically, this eliminates cuspal deformation or gap formation and reduces microleakage.44 Therefore, if the elastic modulus is low, the composite will stretch to accommodate the inherent modulus of the tooth, and the internal layer may absorb the stress of resin composite polymerization shrinkage by elastic elongation.45,46
Also, these lower viscosity flowables may enhance the wetting capacity43 of the restoration, resulting in a more complete internal adaptation, and thereby reduce the formation of voids, which can contribute to a weakened surface and microleakage. An A2/B2 shaded flowable composite (Synergy Flow  [Coltène/Whaledent]) is injected as the syringe tip is slowly retracted, and it is uniformly distributed with a ball-tipped instrument (M-1  [American Eagle]). This technique reduces the possibility of entrapping bubbles and ensures optimal adaptation of the resin material to the adhesive interface. A small increment, 1 to 2 mm in thickness, is applied to the pulpal floor of the class I cavity, and the increment is light-cured for 40 seconds (Figure 10).

The Incremental Layering Technique

Incremental layering has been advocated for use in large composite restorations to avoid the limitation of depth of cure, to reduce the effects of polymerization shrinkage, and to enhance the aesthetic results from the multilayering of color.47,48 However, the anatomy of the tooth should guide the clinician in developing the correct interpretation of form and color. Incremental layering with successive layers of dentin and enamel composite creates high diffusion layers that allow optimal light transmission within the restoration, providing a more realistic depth of color as well as natural surface and optical characteristics. The polychromatic effect is achieved by stratifying variations in shades and opacities of the restorative composite.

Figures 11a and 11b. An A1/B1 shaded composite was applied in increments and condensed using an oblique layering technique (a), and light-cured through the cusp (b).

Due to the variations in natural teeth, the combinations of different composite shades must be applied in relationship to the anatomy of the tooth, and are specifically adapted to different clinical situations. The following technique utilizes both the incremental layering of composite and the stratification of color to create a natural chromatic integration.
The cavity preparation is filled incrementally, utilizing an A1/B1 shaded hybrid composite (Synergy D6) from the preoperative shade-mapping diagram. Each increment is gently condensed with a clean, nonsticking composite condenser (TNCFIS/M [Hu-Friedy]) to ensure complete adaptation to the underlying resin and tooth structure. Each increment is light-cured for 40 seconds using a ramp curing mode (Figures 11a and 11b). The ramp curing mode is a means by which the restoration is initially cured with low-intensity radiation followed by a higher level of power. Sequential use of low-intensity curing light reduces shrinkage stress by controlling the plasticity (flow capacity) of the restoration during curing. The final mechanical stability of the restoration remains unaffected.13,22 When composites are polymerized with high curing light intensities, larger gaps between the cavity walls and the restorative material are created than are found with the use of low-intensity power. Considerable stress reduction occurs during the first 10 seconds of polymerization. Thus, employing lower intensity light during the first 10 seconds extends the visco-elastic stage of setting—an interval in which stress can be partly relieved by flow and elastic strain.49 The correlation between the rate of conversion and the rate of shrinkage stress development requires slower stiffness development, which may result in overall stress reduction.13 Therefore, this reduces the influence of the C-factor at the restorative interface. The reduced initial conversion rate of the resin material allows for better marginal adaptation at the interface of the cavity and restoration,22 which tends to cause less damage at this interface.4,7,13,21,50,51

Figure 12. The internal dentin core was developed with successive increments of composite following the anatomical contours of each cusp.

To reduce the possibility of cuspal flexure, a composite hybrid with a low volumetric polymerization shrinkage should be used.52 Further, this problem may be reduced by a diagonal layering of the hybrid in increments of 1 mm and feathering the material up the cavity wall in a “V” shape.53,54 Opposing enamel walls should not be contacted by the same increment;55 this will minimize the wall-to-wall shrinkage and thus reduce intercuspal stress.56 The application of the composite in oblique layers results in fewer contraction gaps at the margins. It is important to continue to condense and shape the composite resin to correspond to cusp development and replacement of dentin (Figure 12).

Figure 13. An invagination of the final dentin layer was made with an interproximal instrument while the material was still soft to create a developmental groove.

Once the artificial dentin layer is developed, a final preocclusal layer is invaginated with a long-bladed instrument (TNCVIPCL [Hu-Friedy]) while the material is still soft (Figure 13). It is important to anticipate the final result and not overbuild into the artificial enamel zone. In this way space will be allowed for the overlying translucent enamel shade. The internal characteristics (creation of pits and fissures, staining of grooves, and/or the creation of internal color within the restoration) are achieved using a No. 8 endodontic file and a fine sable brush. If the chroma is too high it can be diluted with an untinted resin and a small brush or removed with a clean applicator tip. Each tint is polymerized for 40 seconds and should be polymerized before placement of additional materials to stabilize the characterization and prevent color mixing. In this case, an ochre-tinted resin was applied in the previously formed invagination to correspond to the preoperative shade diagram (Figure 14a).

Figures 14a to 14c. For internal depth, an ochre-tinted resin was applied in the previously formed invagination and light-cured for 40 seconds (a). To create the illusion of an occlusal fissure, a small amount of brown tint was used (b). To achieve a natural transition, a diluted white tint was applied to specific regions along the occlusal planes and faded to the adjacent enamel surface (c).

To create the illusion of occlusal fissure staining, in this case a very small amount of brown tint was applied according to the shade diagram (Figure 14b). Also, a diluted white wash was applied along the occlusal planes to create a smooth, natural transition between the restoration and the higher-valued tooth structure (Figure 14c). This color variation allows the development of a 3-dimensional appearance, providing depth within the restoration.
The enamel or the artificial enamel layer is the principal determinant of the value of the tooth or restoration,57 and this can be varied by the thickness of this layer. The enamel layer can have a white or gray appearance. Modern enamel shades contribute significantly to the total aesthetics of a restoration because they possess many of the optical properties that contribute to the vitality of the tooth—translucency, fluorescence, opalescence, and gloss.58 These characteristics are exemplified on the cusp tips and marginal ridges of posterior teeth as well as on the incisal edges and proximal incisal surfaces of anterior teeth. The nano-composite system used in developing these restorations (Synergy D6) has 2 enamel shades: a higher value white opalescent shade that corresponds to a younger, thicker enamel, and a lower value universal shade that corresponds to mature, thinning enamel. A universal enamel shaded hybrid composite was selected for this 63-year-old patient. To reproduce the optical effects of the enamel, small increments were applied, sculpted with a curved metal instrument, smoothed with a sable brush to the functional and anatomical occlusal morphology, and light-cured for 40 seconds (Figure 15). It is important to re-member that the shade of the restoration ultimately depends on the dentin shades; enamel shades should be used sparingly and cannot be used to anatomically replace human enamel.58

Figure 15. The enamel layer was applied, sculpted with a curved metal instrument, and smoothed with a sable brush.

After placing the last layer of composite and prior to final cure, an oxygen inhibitor, either glycerin (Insure [Cosmedent]) or DeOx (Ultradent Products), is applied to the surface of the restoration in a thin layer with a brush and is then light-cured for 2 minutes to improve the degree of conversion and ensure surface hardness.

Finishing and Polishing Procedure

Figures 16a and 16b. The occlusal anatomy was refined using a No. 30 fluted egg-shaped finishing bur (a). The buccal surface was contoured and finished with a No. 30 fluted needle-shaped bur (b).	Figures 17a and 17b. The margins were etched with a 35% phosphoric acid (a). A composite surface sealant was applied and cured to seal any cracks or microscopic porosities (b).

Developing the restoration in increments and considering the occlusal morphology and occlusal stops allows the clinician to minimize finishing procedures.30 This results in a restoration with improved physical and mechanical characteristics and less potential for microfracture. At least one study has revealed that a reduction in finishing results in less damage to the composite as well as improved wear and clinical performance.54 However, a proper, meticulous finishing protocol can also increase the longevity of the restoration,59,60 since a smooth surface can reduce plaque retention, thus minimizing the potential for gingival inflammation, surface staining, and secondary caries.61-63

Figures 18a and 18b. The final polish was performed with light-cured, resin-impregnated points (a), and a synthetic foam cup, aluminum oxide paste, and the incremental use of water (b).

To reproduce the shape, color, and luster of the natural dentition while enhancing the aesthetics and longevity of the restoration, the following protocol is used. To replicate the natural anatomical form and texture, the initial contouring is performed with a series of finishing burs. In this case the occlusal refinement was achieved with a No. 30 fluted egg-shaped finishing bur (Specialty Carbide Burs, No. 9406 [Midwest]), closely observing the tooth-resin interface and using a dry protocol (Figure 16a). The buccal surface was finished with a No. 30 fluted needle-shaped finishing bur (Specialty Carbide Burs, No. 9714 [Midwest]; Figure 16b). After the initial finishing procedure, the margins and surface defects were sealed. All accessible margins were etched with 35% phosphoric acid, rinsed, and dried. A composite surface sealant (Fortify Plus [Bisco]) was applied and cured to seal any cracks or microscopic porosities that may have formed during the finishing procedures (Figures 17a and 17b). The use of a surface sealant has been shown to reduce the wear rate of posterior composite resin restorations.64 The dental dam was removed, and the patient was asked to perform closure without force, and then centric, protrusive, and lateral excursions. Any necessary occlusal equilibration was accomplished with a No. 8/12 fluted flame-shaped finishing bur (H274 Neumeyer bur [Brasseler USA]). The final polish was initiated with a light-cured resin-impregnated point (Enhance Polishing Point [DENTSPLY Caulk]), which effectively eliminates surface defects. The definitive polish was accomplished with a synthetic foam cup (Enhance Finishing and Polishing System) and aluminum oxide polishing paste (Figures 18a and 18b) at low speed with light pressure and with intermittent use of water. The contact was tested with unwaxed floss to ensure the absence of sealant in the contact zone, and the margins were inspected.
The surface quality of the composite is not only influenced by the polishing instruments and polishing pastes but also by the composition and the filler characteristics of the composite.65 The newer formulations of composites with smaller particle size, shape, and orientation can be polished so as to be comparable to porcelain and enamel. Although the ability to polish these new, small-particle hybrids appears promising, long-term durability of the polished surface will need to be evaluated in clinical trials  

Figure 19. The postoperative result reflects what can be achieved with newer biomaterials utilizing appropriate restorative techniques.

The success of posterior composite restorations requires consideration of function, aesthetics, biocompatibility, and longevity. Achieving success begins with consideration of the adhesive interface. By understanding the relationship between adhesion and polymerization shrinkage, and utilizing the aforementioned stress-reduction techniques, these 4 criteria can be achieved. A restorative material properly bonded to enamel and dentin will reduce marginal contraction gaps, microleakage, marginal staining, and caries recurrence, and will improve retention, reinforce tooth structure, and dissipate and reduce functional stresses. All of this can be accomplished while improving aesthetics and wear resistance.66
The postoperative result in this case reflects the degree of integration that can be achieved between biomaterials and tooth structure utilizing appropriate restorative techniques (Figure 19).

Conclusion

The success of a composite restoration begins at the adhesive interface. Therefore, a successful procedure relies on the selection of restorative materials, preparation design, isolation, adhesive protocol, placement and finishing technique, occlusion, and patient compliance. This article provides the clinician with a defined protocol for achieving a relatively stress-free tooth-composite resin restoration interface by reducing the internal component of stress (shrinkage stress).
Part 2 of this report will describe the external component of stress (occlusal stress) that must be considered with composite resin restorations. Methods for reducing stress during the development of class V composite restorations will be discussed.

References

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2. Roberson TM, Heymann HO, Swift EJ. Sturdevant’s Art and Science of Operative Dentistry. 4th ed. St Louis, Mo: Mosby; 2002:141-148.
3. Craig RG, Powers JM, Wataha JC. Dental Materials: Properties and Manipulation. 8th ed. St Louis, Mo: Mosby; 2004:23-24, 28.
4. Davidson CL, Feilzer AJ. Polymerization shrinkage and polymerization shrinkage stress in polymer-based restoratives. J Dent. 1997;25:435-440.
5. Feilzer AJ, de Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res. 1987;66:1636-1639.
6. Kemp-Scholte CM, Davidson CL. Marginal sealing of curing contraction gaps in class V composite resin restorations. J Dent Res. 1988;67:841-845.
7. Bausch JR, de Lange K, Davidson CL, et al. Clinical significance of polymerization shrinkage of composite resins. J Prosthet Dent. 1982;48:59-67.
8. Bouschlicher MR, Cobb DS, Boyer DB. Radiopacity of compomers, flowable and conventional resin composites for posterior restorations. Oper Dent. 1999;24:20-25.
9. Labella R, Lambrechts P, Van Meerbeek B, et al. Polymerization shrinkage and elasticity of flowable composites and filled adhesives. Dent Mater. 1999;15:128-137.
10. Loshaek S, Fox TG. Cross-linked polymers. I. Factors influencing the efficiency of cross-linking in copolymers of methyl methacrylates and glycol methacrylates. J Am Chem Soc. 1953;75:3544-3550.
11. Quellet D. Considerations and techniques for multiple bulk-fill direct posterior composites [published correction appears in Compend Contin Educ Dent. 1996;17:146]. Compend Contin Educ Dent. 1995;16:1212-1224.
12. Ferracane JL. Using posterior composites appropriately. J Am Dent Assoc. 1992;123:53-58.
13. Feilzer AJ, Dooren LH, de Gee AJ, et al. Influence of light intensity on polymerization shrinkage and integrity of restoration-cavity interface. Eur J Oral Sci. 1995;103:322-326.
14. Davidson CL, de Gee AJ, Feilzer A. The competition between the composite-dentin bond strength and the polymerization contraction stress. J Dent Res. 1984;63:1396-1399.
15. Munksgaard EC, Hansen EK, Kato H. Wall-to-wall polymerization contraction of composite resins versus filler content. Scand J Dent Res. 1987;95:526-531.
16. Iga M, Takeshige F, Ui T, et al. The relationship between polymerization shrinkage measured by a modified dilatometer and the inorganic filler content in light-cured composites. Dent Mater. 1991;10:38-45.
17. Krejci I, Lutz F. Marginal adaptation of class V restorations using different restorative techniques. J Dent. 1991;19:24-32.
18. Alster D, Feilzer AJ, de Gee AJ, et al. The dependence of shrinkage stress reduction on porosity concentration in thin resin layers. J Dent Res. 1992;71:1619-1622.
19. Fan PL, Edahl A, Leung RL, et al. Alternative interpretations of water sorption values of composite resins. J Dent Res. 1985;64:78-80.
20. Soltesz U, Bath P, Klaiber B. Dimensional behavior of dental composites due to polymerization shrinkage and water sorption. In: Christel P, Meunier A, Lee AJC, eds. Biological and Biomechanical Performance of Biomaterials. Amsterdam: Elsevier; 1986:123-128.
21. Unterbrink GL, Muessner R. Influence of light intensity on two restorative systems. J Dent. 1995;23:183-189.
22. Uno S, Asmussen E. Marginal adaptation of a restorative resin polymerized at reduced rate. Scand J Dent Res. 1991;99:440-444.
23. Grippo JO. Abfractions: a new classification of hard tissue lesions of teeth. J Esthet Dent. 1991;3:14-19.
24. Heymann HO, Sturdevant JR, Brunson WD, et al. Twelve-month clinical study of dentinal adhesives in class V cervical lesions. J Am Dent Assoc. 1988;116:179-183.
25. Lee WC, Eakle WS. Possible role of tensile stress in the etiology of cervical erosive lesions of teeth. J Prosthet Dent. 1984;52:374-380.
26. Leinfelder KF. Restoration of abfracted lesions. Compendium. 1994;15:1396-1400.
27. Kemp-Scholte CM, Davidson CL. Complete marginal seal of class V resin composite restorations effected by increased flexibility. J Dent Res. 1990;69:1240-1243.
28. Fahl N Jr, Denehy GE, Jackson RD. Protocol for predictable restoration of anterior teeth with composite resins. Pract Periodontics Aesthet Dent. 1995;7:13-21.
29. Winter R. Visualizing the natural dentition. J Esthet Dent. 1993;5:102-117.
30. Liebenberg WH. Successive cusp build-up: an improved placement technique for posterior direct resin restorations. J Can Dent Assoc. 1996;62:501-507.
31. Croll TP. Alternative methods for use of the rubber dam. Quintessence Int. 1985;16:387-392.
32. Liebenberg WH. General field isolation and the cementation of indirect restorations: part 1. J Dent Assoc S Afr. 1994;49:349-353.
33. Kidd EA, Joyston-Bechal S, Beighton D. The use of a caries detector dye during cavity preparation: a microbiological assessment. Br Dent J. 1993;174:245-248.
34. Sturdevant CM, Roberson TM, Heymann HO, et al. The Art and Science of Operative Dentistry. 3rd ed. St Louis, Mo: Mosby-Year Book; 1995.
35. Leinfelder KF. A conservative approach to placing posterior composite resin restorations. J Am Dent Assoc. 1996;127:743-748.
36. Small BW. Direct posterior composite restorations – state of the art 1998. Gen Dent. 1998;46:26-32.
37. Leinfelder KF. Using composite resin as a posterior restorative material. J Am Dent Assoc. 1991;122:65-70.
38. Strassler HE. Esthetic posterior restorations: direct composite resins. J Esthet Dent. 1992;4:216-220.
39. Kanca J III. Improving bond strength through acid etching of dentin and bonding to wet dentin surfaces. J Am Dent Assoc. 1992;123:35-43.
40. Nakabayashi N, Nakamura M, Yasuda N. Hybrid layer as a dentin-bonding mechanism. J Esthet Dent. 1991;3:133-138.
41. Kanca J III. Resin bonding to wet substrate. II. Bonding to enamel. Quintessence Int. 1992;23:625-627.
42. Estafan AM, Estafan D. Microleakage study of flowable composite resin systems. Compend Contin Educ Dent. 2000;21:705-712.
43. Frankenberger R, Krämer N, Pelka M, et al. Internal adaptation and overhang formation of direct class II resin composite restorations. Clin Oral Investig. 1999;3:208-215.
44. Prager MC. Using flowable composites in direct posterior restorations. Dent Today. 1997;16:62-69.
45. Van Meerbeek B, Perdigao J, Lambrechts P, et al. The clinical performance of adhesives. J Dent. 1998;26:1-20.
46. Lindberg A, van Dijken JW, Hörstedt P. Interfacial adaptation of a class II polyacid-modified resin composite/resin composite laminate restoration in vivo. Acta Odontol Scand. 2000;58:77-84.
47. Tjan AH, Glancy JF. Effects of four lubricants used during incremental insertion of two types of visible light-activated composites. J Prosthet Dent. 1988;60:189-194.
48. Kovarik RE, Ergle JW. Fracture toughness of posterior composite resins fabricated by incremental layering. J Prosthet Dent. 1993;69:557-560.
49. Dennison JB, Yaman P, Seir R, et al. Effect of variable light intensity on composite shrinkage. J Prosthet Dent. 2000;84:499-505.
50. Reinhardt RJ. Effect of the light source on the marginal adaption of composite fillings [in German]. Dtsch Zahnarztl Z. 1991;46:132-134.
51. Goracci G, Mori G, Casa de’ Martinis L. Polimerizzazione di materiali compositi: valutazione di due metodi. Dental Cadmos. 1993;7:50-63.
52. Rees JS, Jacobsen PH. Restoration of posterior teeth with composite resin. 1: Direct-placement composite. Dent Update.

Dr. Terry received his DDS from the University of Texas Health Science Center Dental Branch at Houston in 1978. He has published more than 230 articles on various topics in aesthetic dentistry in numerous languages and authored the textbook Natural Aesthetics with Composite Resin. He is an assistant professor, Department of Restorative Dentistry and Biomaterials, at the University of Texas Health Science Center Dental Branch at Houston and is a Fellow in the AGD and the International Academy for Dental-Facial Esthetics. Dr. Terry maintains a private practice in Houston emphasizing aesthetic and restorative dentistry. He can be reached at (281) 481-3483.

Dr. Leinfelder earned his doctor of dental surgery and master of science (dental materials) degrees from Marquette University. After serving for 8 years on the faculty at Marquette, he joined the faculty at the University of North Carolina School of Dentistry, where he attained the rank of professor and director of biomaterials clinical research in the Dental Research Center. In 1983, he joined the School of Dentistry at the University of Alabama and held the Joseph Volker Chair. He also served as chairman of the Department of Biomaterials until 1994. Presently he holds positions at both universities: adjunct professor at the University of North Carolina and professor emeritus at the University of Alabama. He is the recipient of the Dr. George Hollenbeck award (1995) as well as the Norton N. Ross award for outstanding clinical research (1997), and the American College of Prosthodontists Distinguished Lecturer Award (1998). He has served as associate editor of the Journal of the American Dental Association. He can be reached at (919) 370-9168.

CASE REPORT

Initial Examination

Figure 1. The patient with a high lip line at smile. Note the presence of exposed crown margins on the central incisors as well as the bluish hue of the anterior gingiva.	Figure 2. Uneven gingival margin with size and shape discrepancies among the maxillary anterior teeth. Note the presence of a large amalgam tattoo with scarring from previous periapical surgery.

A 45-year-old healthy white female presented with a chief complaint that she “was embarrassed to smile because of the appearance of her teeth and discolored gums” (Figure 1). She had a high lip line and an uneven gingival line. There was a size and shape discrepancy among her maxillary anterior teeth (Figure 2). The maxillary left central incisor crown was greatly overcontoured. The crown margins of the central incisors were exposed, contributing to the poor aesthetics. Periodontal evaluation determined probing depths of 4 to 5 mm in the anterior sextant, and the tissue bled upon probing. The patient had thick gingiva that appeared edematous, and the marginal tissue was inflamed and enlarged.
Radiographic examination demonstrated mild horizontal bone loss. Multiple discolored and open composite restorations were seen on the remaining incisor and cuspid teeth. A very large area of discoloration was present in the maxillary anterior segment. The patient had a history of apical surgery on all 4 incisor teeth. The tissue was not only discolored but also demonstrated extensive scarring of the mucosa that was further evidence of the previous surgical interventions.

Sequence of Therapy

1. Initial supragingival and subgingival debridement and oral hygiene instruction.
2. Thorough root planing and scaling.
3. Provisional restorations to improve both the patient’s appearance and ability to cleanse the area.
4. Surgical removal of the large amalgam tattoo.
5. Aesthetic crown lengthening to establish symmetry and correct the tooth size/shape discrepancies.

Figure 3. The affected hard and soft tissue has been removed. Note the presence of lesions over the apices that were filled with amalgam.	Figure 4. The beveled edge of the graft placed coronally to blend with the surrounding soft tissue.
Figure 5. One-week follow-up.	Figure 6. Two-week follow-up.
Figure 7. Aesthetic crown lengthening of maxillary right cuspid, lateral, and central incisor teeth and removal of fibroma between the maxillary central incisors.	Figure 8. Two-year follow-up.

Removal of the amalgam tattoo was performed utilizing a circumferential incision with a 1-mm clear border around the margins of the lesion. The affected tissue was excised (Figure 3). The remaining amalgam deposits were debrided first with curettes and later with high-speed rotary instruments utilized on the affected bone. Near the apices of the teeth, large round defects were found to be filled with amalgam and granulomatous tissue. After thoroughly debriding these defects, they were filled with demineralized freeze-dried bone allograft. A large free gingival graft (30 x  10 mm) was then removed from the left side of the posterior palate using an angled blade holder. The graft was placed at the recipient site in such a way that the beveled edge was directed coronally to blend with the surrounding tissues (Figure 4). The graft was then secured with 5-0 chromic gut suture using a continuous loop. It was carefully adapted to the underlying bed with cross-sutures secured to the periosteum. Periodontal dressing (COE-PAK [GC America]) was applied to the graft to protect the wound and maintain vestibular depth.
After one week, the graft appeared to be well vascularized and was beginning to blend in with the surrounding tissue despite slough of the surface epithelium (Figure 5). At 2 weeks, a wide zone of epithelialized at tached gingiva was present. The discolored scar tissue could no longer be observed (Figure 6).
After 8 weeks of healing, the second phase of the periodontal surgery was performed to establish symmetry and correct the size and shape discrepancies in the aesthetic zone. After bone sounding, it was determined that the patient could maintain adequate biologic width even after the removal of 1 to 2 mm of keratinized tissue. Gingivectomy/gingivoplasty was determined to be the least invasive and most efficient approach. After careful measurement, it was decided to remove 1 to 2 mm of gingiva in a scalloped incision on the right cuspid, lateral incisor, and central incisor teeth in order to achieve symmetry with the left side (Figure 7).
After 8 weeks of healing, the final restorations were inserted. The patient was pleased with the aesthetic results that addressed her chief complaint. At the 2-year postoperative visit, the periodontium and anterior dentition appeared to be healthy, and there was no rebound from the crown lengthening, nor was there recurrence of the amalgam tattoo (Figure 8).

DISCUSSION

The patient presented with at least 3 aesthetic problems: an uneven gingival margin when comparing the maxillary right and left anterior segments, an overcontoured crown on the maxillary left central incisor, and a large amalgam tattoo and scar tissue in the anterior apical area. The patient also had a high lip line. Discussion and communication with the pa tient and restorative dentist are crucial in a case with multiple problems, and should be accomplished very early in the sequence of appointments. In this case, the goal of the initial treatment (scaling and root planing, provisional restoration) was to reduce gingival inflammation and improve home care. Only when gingival inflammation has been reduced can the treatment plan, including consideration of aesthetic concerns, be fully developed. During the surgical phase the unpleasant amalgam tattoo and scar tissue were re moved, and the gingival line was altered by means of aesthetic crown lengthening. Finally, permanent crowns with proper contour and color were fabricated.
Several surgical modalities have been advocated for the treatment of an amalgam tattoo.10,13-17 One of the first approaches that was introduced for small, superficial lesions is to perform a localized gingivoplasty with a rotary instrument.10 Ashinoff and Tanenbaum documented the use of a Q-switched ruby laser in the anterior maxilla area.13 For larger lesions, a free gingival autograft, sub-epithelial connective tissue graft, or an allograft (acellular dermal matrix) have been suggested approaches.14,16-17  Autogenous soft-tissue grafts are limited by tissue availability and the second surgical site to collect donor tissue. This donor site may increase postsurgical complications and patient discomfort. In one technique, a second-stage surgery is required for further removal of tissue that contains amalgam.16 Allo-graft substitution, as described by Griffin, et al, eliminates the need for a second surgical donor site.17 Patient acceptance is often a consideration. In this case, after clinical examination it was found that not only did the patient have what can be described as a thick periodontium, but also that an adequate amount of autogenous tissue could be harvested from the palate. Therefore, based on the clinical findings and with consideration of the patient’s desires, a free gingival autograft technique was chosen.
Techniques of aesthetic crown lengthening and their indications have been described in the literature.7,18-19 Prior to the procedure, the following criteria should be considered:

• ideal gingival line
• amount of keratinized tissue that is present
• crown-to-root ratio
• characteristics of the periodontium, ie, thickness
• biological width.

Then, an appropriate surgical technique is applied based on the evaluation. If removal of marginal alveolar bone is not required and the amount of attached gingiva is adequate (ie, Type IA), then gingivectomy is the choice with or without gingivoplasty. If an adequate amount of attached gingiva (ie, Type IIA) and biological width needs to be established (ie, Type B subgroups) by removing labial crestal alveolar bone, then a flap procedure is employed for access. In the case presented, since the base of the sulcus was at least 2 mm away from the future crown margin and there was an adequate amount of keratinized tissue (ie, Type 1A), it was determined that gingivectomy by internal bevel incision was the best approach to achieve the desired final result.

CONCLUSION

A case has been described in which the patient presented with multiple aesthetic, prosthetic, and periodontal problems. The diagnostic assessment, treatment planning, and surgical procedures used to address these problems illustrate the importance of a multidisciplinary approach in the restoration of such cases.

References

1. Dong JK, Jin TH, Cho HW, et al. The esthetics of the smile: a review of some recent studies. Int J Prosthondont. 1999;12:9-19.
2. Garber DA, Salama MA. The aesthetic smile: diagnosis and treatment. Periodontol 2000. 1996;11:18-28.
3. Ezquerra F, Berrazueta MJ, Ruiz-Capillas A, et al. New approach to the gummy smile. Plast Reconstr Surg. 1999;104:1143-1152.
4. Caudill R, Chiche G. Establishing an esthetic gingival appearance. In: Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Hanover Park, Ill: Quintessence Publishing Co; 1994.
5. Weinberg MA, Eskow RN. An overview of delayed passive eruption. Compend Contin Educ Dent. 2000;21:511-518.
6. Dolt AH III, Robbins JW. Altered passive eruption: an etiology of short clinical crowns. Quintessence Int. 1997;28:363-372.
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9. Kennedy JE, Bird WC, Palcanis KG, et al. A longitudinal evaluation of varying widths of attached gingiva. J Clin Periodontol. 1985;12:667-675.
10. Buchner A, Hansen LS. Amalgam pigmentation (amalgam tattoo) of the oral mucosa. A clinicopathologic study of 268 cases. Oral Surg Oral Med Oral Pathol. 1980;49:139-147.
11. Holmstrup P. Reactions of the oral mucosa related to silver amalgam: a review. J Oral Pathol Med. 1991;20:1-7.
12. Owens BM, Schuman NJ, Johnson WW. Oral amalgam tattoos: a diagnostic study. Compendium. 1993;14:210-214.
13. Ashinoff R, Tanenbaum D. Treatment of an amalgam tattoo with the Q-switched ruby laser. Cutis. 1994;54:269-270.
14. Dello Russo NM. Esthetic use of a free gingival autograft to cover an amalgam tattoo: report of case. J Am Dent Assoc. 1981;102:334-335.
15. Shiloah J, Covington JS, Schuman NJ. Reconstructive mucogingival surgery: the management of amalgam tattoo. Quintessence Int. 1988;19:489-492.
16. Kissel SO, Hanratty JJ. Periodontal treatment of an amalgam tattoo. Compend Contin Educ Dent. 2002;
23:930-936.
17. Griffin TJ, Banjar SA, Cheung WS. Reconstructive surgical management of an amalgam tattoo utilizing an acellular dermal matrix graft: case reports. Compend Contin Educ Dent. 2005;26:853-859.
18. Minsk L. Esthetic crown lengthening. Compend Contin Educ Dent. 2001;22:562-569.
19. Sonick M. Esthetic crown lengthening for maxillary anterior teeth. Compend Contin Educ Dent. 1997;18:807-819.

Acknowledgment

The authors wish to acknowledge Dr. Andrew Kurban, who was the restorative dentist involved in this case.

Dr. Griffin received both his DMD and his Certificate of Advanced Graduate Studies in Periodontology from Tufts University. He is a Diplomate of the American Board of Periodontology and is chair and director of postdoctoral periodontology at Tufts University School of Dental Medicine. He has published articles on periodontal plastic surgery and implantology in a variety of journals and has lectured nationally and in 19 foreign countries. He is a former president of the Massachusetts Periodontal Society. Dr. Griffin also maintains a practice in Boston limited to periodontology, implantology, and oral diagnosis. He can be reached at (617) 536-4545 or terrence.griffin@tufts.edu.

Dr. Engler-Hamm serves on the board of the Magazine Dentale Implantologie und Parodontologie as a consultant, and he has published several case reports in the field of periodontology and implant dentistry. At present, he is a third-year resident in the post-graduate periodontics program at Tufts University School of Dental Medicine. He is also the 2006 Lazzara Scholarship recipient from the American Academy of Periodontology Foundation. He can be reached at (617) 636-6531 or Daniel.Engler_Hamm@tufts.edu.

Dr. Cheung completed her residency in periodontics and earned a master’s of science degree from the graduate school of Tufts University. She is a Diplomate of the American Board of Periodontology and has authored articles on periodontal plastic surgery and implantology. She is currently an assistant professor in the Department of Periodontology, Tufts University School of Dental Medicine. She can be reached at (617) 636-6531 or wai.cheung@tufts.edu.

Continuing Education Test No. 83.1

After reading this article, the individual will learn:

• the crucial factors in making a diagnosis and case assessment in the aesthetic zone, and
• to identify incomplete passive eruption and amalgam tattoo lesions, and treatment modalities to correct these problems.

1. The reasons for excessive gingival display at smile could be ____.

a. skeletal, eg, associated with maxillary prognathism
b. a short upper lip
c. incomplete passive eruption (IPE)
d. all the above

2. Incomplete passive eruption (IPE) is a term used to describe the anatomical condition where the free gingival margin is located more than ____ coronal to the cementoenamel junction (CEJ).

a. 1 mm
b. 2 mm
c. 4 mm
d. 6 mm

3. Incomplete passive eruption (IPE) can be managed by ____.

a. making a longer crown
b. making a longer veneer
c. aesthetic crown lengthening
d. observing

4. Coslet, et al classified incomplete passive eruption (IPE) into 2 types according to ____.

a. hard-tissue relationship
b. length of the affected tooth
c. soft-tissue dimensions
d. thickness of the alveolar crest

5. Coslet, et al further divided incomplete passive eruption (IPE) into 2 subgroups
according to ____.

a. hard-tissue relationship
b. length of the affected tooth
c. soft-tissue dimension
d. thickness of the alveolar crest

6. Amalgam can be incorporated into the oral mucosa through ____.

a. condensation of the material into gingival tissue during the placement of amalgam restoration
b. damage to the gingiva by a cutting instrument during removal of an existing amalgam restoration
c. corrosion of retrograde amalgam restoration of endodontically treated teeth
d. all the above

7. Surgical approaches in the treatment of amalgam tattoo lesions include the use of ____.

a. free gingival autograft
b. subepithelial connective tissue graft
c. acellular dermal matrix allograft
d. all the above

8. In a case with multiple problems, ____ are crucial and should be accomplished very early in the sequence of appointments.

a. discussion and communication with the patient and restorative dentist
b. oral hygiene instruction, scaling, and root planing
c. discussion with the patient and oral hygiene instruction
d. communication with the restorative dentist and oral hygiene instruction to the patient

To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 83.1), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).

BACKGROUND

Figure 1. Images taken with CBCT technology are easy to understand and accurately represent the patient’s craniofacial structures. (Note: The CB MercuRay [Hitachi Medical Corporation] was used to produce the images in Figures 1 to 3 and 6 to 11.)	Figure 2. The CBCT image can be seen as slices or cuts, separated by sagittal, coronal, and axial views, with reference lines that make it easy to understand the location of the area being examined.

Figure 3. The field of view represents the area that can be captured when imaging a patient. Possible fields of view include (A) 3 inches, (B) 6 inches, (C) 9 inches, and (D) 12 inches. (Image courtesy of Hitachi Medical Systems America.)

CBCT is a method to acquire 3-dimensional radiographic images that is becoming increasingly popular in dentistry. The resulting images are user-friendly and provide far more information than conventional 2-dimensional radiographs. Three-dimensional imaging is capable of capturing both skeletal and soft tissues, which can then be displayed together or separately (Figure 1). Like earlier CT technology such as spiral and fan CT, “slice-by- slice” axial, sagittal, and coronal images can be observed, but CBCT software also incorporates reference lines that make location of these slices less complicated. For example, even when observing only the coronal view or a small segment of a complete image, lines in the sagittal slice view will indicate the height and position of the slice or object being analyzed (Figure 2).
CBCT is digital by nature and uses a computer program to construct a 3-dimensional volume from a series of 250 to 300 2-dimensional images. CBCT terminology reflects that emphasis. For instance, voxel is used instead of pixel, since it is referring to volume and not to a 2-dimensional space. The image files are the DICOM (Digital Imaging and Communications in Medicine) standard, namely, the universal format for 3-dimensional images in the medical field.1 Therefore, a 3-dimensional CBCT image will have a file extension of “dcm,” instead of a digital picture that would have an extension such as “tif,” “jpeg,” etc.
The region of interest, usually abbreviated as ROI, is the 3-dimensional volume that the clinician wants to evaluate. For example, when asking for a periapical radiograph of the mandibular incisors, the ROI is that incisor area. The smaller the ROI, the better the resolution obtained for that image. The resolution often is related to the size of the field of view (FOV), which is the resulting size of the image (Figure 3). For example, if the clinician wants to visualize a cyst in the mandibular incisor area, and a large FOV that includes the entire head is used, the observer must zoom to the ROI, and the image quality will not be as good as a FOV that was focused only in that incisor area.
This concept is similar to what occurs for digital photography. If the clinician wants to see a central incisor in detail, a good starting point would be an intraoral picture of the target area, not the full smile. In the latter scenario, zooming in would make the incisor appear fuzzy, indicating poor resolution. The resolution in CBCT images ranges from 0.1 to 0.5 mm.

CONE BEAM COMPUTERIZED TOMOGRAPHY

Figure 4. Illustration showing the difference between the data capture system of regular CT and CBCT. (A) A regular CT machine captures the data in a fan fashion; (B) the CBCT captures the data in a volumetric fashion.

Craniofacial CBCT was designed to counter some of the limitations of earlier generations of CT scanning devices and to make 3-dimensional technology practical for dentistry. The radiation source consists of a conventional, low-radiation x-ray tube, and the resultant beam is projected onto a panel detector, producing a more focused beam and considerably less scatter radiation compared to the helical CT devices (Figure 4).2,3,4 The total radiation is approximately 20% of that of a helical CT and can be equivalent to exposure during a full-mouth periapical series.5
The innovations mentioned above are significant, since they allow the CBCT unit to be less expensive and smaller in size than a traditional CT machine. When compared to earlier generation CT scanners, CBCT is more sensitive and more accurate, requires less radiation, captures the maxilla and mandible in a single rotation of the x-ray source, and is more cost-effective for patients.6,7,8 Another advantage of the CBCT technology over earlier generations of CT such as helical CT is the low level of metal artifacts in primary and secondary reconstructions.9 An image taken with helical CT of an area close to a metallic restoration, a crown, or an implant is very difficult to analyze and diagnose because of the artifacts and distortions that the presence of the metal would create. This is a major limitation in the use of helical CT images, since many patients have metal present in their mouths. With CBCT technology, the area around the metal presence is usually of diagnostic quality. CBCT offers surface as well as radiographic view modes. The latter are similar to traditional radiographs familiar to dental practitioners.

Figure 5. Currently available cone beam scanners approved for use in dentistry: (A) NewTom 3G (courtesy of Aperio Services); (B) ILUMA (courtesy of IMTEC); (C) CB MercuRay (courtesy of Hitachi Medical Systems America); (D) i-CAT (courtesy of Imaging Sciences); and (E) 3D Accuitomo (courtesy of J. Morita USA).

Five CBCT systems are currently on the market, and 2 other systems will soon be available. The available CBCT systems (Figure 5) are NewTom 3G (Quantitative Radiology), i-CAT (Imaging Sciences International), CB MercuRay (Hitachi Medical Corporation), 3D Accuitomo (J. Morita Manufacturing), and the ILUMA (IMTEC Imaging). The available CBCT machines differ in size, settings, area of image capture (field of view), and clinical usage (Table).
The NewTom 9000 was the first CBCT device for the dental market. When using a NewTom, the patient is imaged in a supine position, and scans of the head and neck are completed in 36 seconds. The system offers 3 possible fields of views (6, 9, and 12 inches). According to the manufacturer, the system is able to produce a voxel resolution up to 0.16 mm.
The i-CAT cone beam system captures the image with the patient sitting upright, and the scan time varies from 20 to 40 seconds. According to the manufacturer, the i-CAT provides no distortion, a 12-bit grayscale, and a voxel size resolution of 0.2 mm. One early criticism of the system was the distortion of the facial tissues a chin rest produced when the patient was positioned in the device. Imaging Sciences has improved the patient positioning device, and this problem has been eliminated in the later versions.

The CB MercuRay is a considerably larger unit and allows for different fields of view. A scan time of 10 seconds through a rotation of 360° provides 288 views that can be seen either as 2-dimensional or 3-dimensional images. The CB MercuRay offers 3 different fields of view and is the fastest CBCT machine currently available. This is an advantage, since patient movement is reduced during image capture.
The 3D Accuitomo was developed as a collaboration between the School of Dentistry at Nihon University and J. Morita Manufacturing. This apparatus focuses on specific structures, offering a field of view of approximately 1.2×1.6 inches. This compact unit has the advantage of requiring only 1.6 times the space of a conventional dental panoramic machine.
The ILUMA is the latest full-view head-and-neck imaging CBCT and uses a fixed field of view. The ILUMA is available as 2 different versions, the OrthoCAT and the DentalCAT, with respective fields of view of 7.5×7.5 inches and 4×6.7 inches.

CLINICAL APPLICATIONS OF CBCT IN DENTISTRY

With CBCT technology, all radiographic images can be taken in less than a minute. Dental clinicians can have the diagnostic quality of periapical radiographs, panoramic radiographs, cephalograms, occlusal radiographs, and TMJ images at their disposal, along with views that cannot be produced with regular radiographic machines such as axial and cross-sectional views. A number of clinical applications have already been reported in the literature.10 A search of the peer-reviewed dental literature from 1966 to 2006 was performed using Medline and PubMed, a review of pertinent dental textbooks, the Internet, and personal communication with authors and organizations. The key words used were Cone Beam, CBCT, and CBVT. The results were analyzed in order to find reports and comments on clinical applications of CBCT technology in dentistry. The results were as follows:

Impacted Teeth

Figure 6. CBCT images of a patient with an impacted supernumerary tooth. (A) anterior view of the maxilla in the radiographic mode; (B) view of the right half of the maxilla in the radiographic mode; (C) surface view of the anterior right segment of the maxilla; (D) anterior view of the maxilla in the surface mode; and (E) occlusal view of the maxilla in the radiographic mode.

Impacted maxillary cuspids have been reported to be distributed as 85% palatal and 15% buccal.11 The tube shift method has traditionally been used to locate the position of these cuspids and provides an approximation of the level of difficulty associated with the management of these teeth. This method is labor intensive.  
The use of CBCT has proven useful in the management of patients with impacted teeth (Figure 6).11,12 The CBCT allows for a more precise analysis of the extent of the pathology related to the ectopic tooth. Clinical reports using 3-dimensional imaging have shown that the incidence of root resorption of teeth adjacent to impacted teeth is greater than previously thought.11 CBCT images can be used to locate the precise position of ectopic cuspids and to design treatment strategies that would result in less invasive surgical intervention. Computer-and image-guided surgical exposure allows for less invasive surgery, smaller incisions, more conservative flap design, and overall reduced morbidity associated with the surgery. 11,12

PATHOLOGY

Figure 7. CBCT images of a patient with a mandibular cyst. (A) mesial view of right half of the mandible in surface mode; (B) anterior view of the mandible in the surface mode with measurements in mm; (C) lingual view of the mandible in surface mode with measurements in mm; (D) radiographic cross-sectional view of the maxilla and mandible, and (E) panoramic view.

Another use of CBCT is the location of (oral) pathologic lesions such as periapical cysts (Figure 7). CBCT has been evaluated for the detection of carious lesions and has shown better results than F-speed film in assessing the depth of proximal lesions.13  Centers including Case Western Reserve University and Loma Linda University, among others in the United States, have begun to adopt CBCT imaging into routine dental examination procedures.  Preliminary, unreported findings suggest that the  incidence of oral abnormalities, ie, cysts, ectopic teeth, and supernumerary teeth, is higher than previously suspected.

Airway Analysis

Figure 8. Analysis of the airway with only a lateral film would not be able to identify a possible airway lateral constriction abnormality. With CBCT the airway can be segmented and analyzed volumetrically in 3 dimensions.

CBCT technology provides a major improvement for evaluation of the airway, allowing for 3-dimensional and volumetric determinations (Figure 8). Airway analysis conventionally has been carried out by using lateral cephalograms. A recent study comparing lateral cephalograms to CBCT imaging found that there was moderate variation in the measurements of upper airway area and volume.14 Three-dimensional airway analysis will be useful for the understanding of more complex conditions such as obstructive sleep apnea (OSA) and enlarged adenoids. CBCT has demonstrated significant differences in airway volume and the anteroposterior dimension of the oropharyngeal airway between OSA patients and gender-matched controls.15

Implant Planning and Bone Quality Assessment

Figure 9. Alveolar height and width assessment used for planning dental implants. The CBCT image gives a true 1:1, 3-dimensional representation of the patient.

Implantologists have long appreciated the value of 3-dimensional imaging. Conventional CT scans are used to assess the osseous dimensions, bone density, and alveolar height, especially when multiple implants are planned (Figure 9). Locating landmarks and anatomy such as the inferior alveolar canal, maxillary sinus, and mental foramen occurs more accurately with a CT scan. The use of the third dimension has improved the clinical success of implants and their associated prostheses, and led to more accurate and aesthetic outcomes.16-22
With CBCT technology both the cost and effective radiation dose can be reduced. CBCT has been in use in implant therapy and may be employed in orthodontics for the clinical assessment of bone graft quality following alveolar surgery in patients with cleft lip and palate.23,24 The images produced provide more precise evaluation of the alveolus. This technology can help the clinician determine if the patient should be restored or if teeth should be moved orthodontically into the repaired alveolus.

Location of Anatomic Structures

Figure 10. Images produced from a single exposure for the purpose of dental implant planning. The images here are panoramic and cross-sectional views with the mandibular canal marked, as well as a surface and radiographic (maximum intensity projection) view with the stent in place.

Anatomic structures such as the inferior alveolar nerve, maxillary sinus, mental foramen, and adjacent roots are easily visible using CBCT (Figure 10).18 The CBCT image also allows for precise measurement of distance, area, and volume. Using these features, clinicians can feel confident in the treatment planning for sinus lifts, ridge augmentations, extractions, and implant placements.

Temporomandibular Joint (TMJ) Morphology

Figure 11. Different possible views of the TMJ complex by using CBCT, showing in this case a fracture. (A) and (B) surface mode showing the extent of the fracture; (C) radiographic mode; (D) panoramic view; and (E) cross-sectional view in the radiographic mode.

CBCT imaging of the temporomandibular joint has been evaluated and compared to other methods.7,25,26,27 Results indicate better imaging with CBCT compared to traditional radiography and helical CT.7 The CBCT showed greater sensitivity and accuracy than the helical CT in the identification of mandibular condyle abnormalities. Condylar resorption is reported to occur in 5% to 10% of patients who undergo orthognathic surgery.28 Recent 3-dimensional studies have attempted to understand how the condyle remodels, and preliminary data suggest that much of the condylar remodeling is a direct result of the surgical procedure.28 TMJ changes following distraction osteogenesis and dento-facial orthopedics require further study.
CBCT images provide high diagnostic quality (Figure 11) with lower patient radiation exposure as compared to conventional CT techniques. Therefore, CBCT should be considered as the imaging technique of choice when investigating bony changes of the TMJ.25

Orthodontics

CBCT technology is able to capture all radiographic records necessary for orthodontic diagnosis in less than 1 minute.29 Three-dimensional visualization of the patient allows for a more accurate evaluation of both dental and skeletal asymmetries and can provide a more thorough outcome assessment.

RADIATION EXPOSURE

Even though cone beam technology is able to provide 3-dimensional volumetric images with up to 4 times less radiation than a conventional CT,30,31 the effective radiation depends on the settings used (kVp and mA). The use of lower mA and/or collimation are some of the ways to reduce the amount of radiation, but at the same time the image quality may suffer. Exposure dose from a CBCT machine has been reported to be as low as 45 µSv (micro-sievert, SI unit for ionizing radiation) to as high as 650 µSv.32,33 Exposure from a full-mouth series of analog radiographs has been reported to be 150 µSv,34 and 54 µSv for an analog panoramic radiograph.35,36 As a comparison, a roundtrip airplane flight from Paris to Tokyo exposes passengers to an effective dose of 139 µSv.37,38
In 2001, a report associating the use of conventional CT in children to radiation-induced cancer39 resulted in CTs being adjusted downward to have an effective dose ranging from 2,600 µSv to 6,000 µSv.40 Even at the highest settings possible, none of the CBCT units will provide anything near that dose.
The ADA Council on Scientific Affairs recommends the use of techniques that would reduce the amount of radiation received during dental radiography. Known as the As Low As Reasonably Achievable (ALARA) principle, this includes taking radiographs based on the patient’s needs (as determined by a clinical examination), using the fastest film compatible with the diagnostic task, collimating the beam to a size as close to that of the film as feasible, and using leaded aprons and thyroid shields.41 An accepted ratio between exposure and image quality needs to be reached in order to apply the ALARA principle. Depending on the objective and desired outcome, alternative technologies should be explored, since it may offer a less invasive way of creating a 3-dimensional image.42,43

DISCUSSION

CBCT is capable of imaging hard-tissue and most soft-tissue structures. However, this technology does not have the ability to precisely map muscles and their attachments. These structures would have to be imaged using conventional magnetic resonance imaging technology, which does not expose the patient to ionizing radiation. Further, CBCT soft-tissue images do not show the color of the skin. In order to obtain photographic quality results, manipulation of the images is required. Successful attempts to add tissue color maps to conventional CTs have been reported and may eventually be applied to CBCT technology.43 This may be an alternative to extraoral photography. Meanwhile, devices such as stereo-photogrammetry and laser scanning are still the state of the art for capturing soft-tissue color images.
As with all new technology, cost is a major concern. Cost of a CBCT machine can range from $150,000 to $300,000. All 5 companies sell the CBCT devices as standard base packages; peripherals can increase the cost. Also, a substantial post-purchase maintenance cost is required for most systems. The purchase of a CBCT system is very different than the purchase and use of traditional radiographic systems and generally requires a dedicated staff member with considerable training.

CONCLUSION

The incorporation of the third dimension into practical dental and craniofacial imaging is now a reality. The future of craniofacial and dental imaging is exciting as the paradigm shifts from landmarks, lines, distances, and angles to surfaces, areas, and volumes.

References

1. Farman AG. Raising standards: digital interoperability and DICOM. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;99:525-526.
2. Danforth RA, Peck J, Hall P. Cone beam volume tomography: an imaging option for diagnosis of complex mandibular third molar anatomical relationships. J Calif Dent Assoc. 2003;31:847-852.
3. Mah J, Hatcher D. Current status and future needs in craniofacial imaging. Orthod Craniofac Res. 2003;6(suppl 1):10-16; 179-182.
4. Sukovic P. Cone beam computed tomography in craniofacial imaging. Orthod Craniofac Res. 2003;6(suppl 1):31-36; 179-182.
5. Mah JK, Danforth RA, Bumann A, et al. Radiation absorbed in maxillofacial imaging with a new dental computed tomography device. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003;96:508-513.
6. Winter AA, Pollack AS, Frommer HH, et al. Cone beam volumetric tomography vs. medical CT scanners. N Y State Dent J. 2005;71:28-33.
7. Honda K, Larheim TA, Maruhashi K, et al. Osseous abnormalities of the mandibular condyle: diagnostic reliability of cone beam computed tomography compared with helical computed tomography based on an autopsy material. Dentomaxillofac Radiol. 2006;35:152-157.
8. Hashimoto K, Kawashima S, Araki M, et al. Comparison of image performance between cone-beam computed tomography for dental use and four-row multidetector helical CT. J Oral Sci. 2006;48:27-34.
9. Heiland M, Schulze D, Blake F, et al. Intraoperative imaging of zygomaticomaxillary complex fractures using a 3D C-arm system. Int J Oral Maxillofac Surg. 2005;34:369-375.
10. Danforth RA, Dus I, Mah J. 3-D volume imaging for dentistry: a new dimension [published correction appears in J Calif Dent Assoc. Dec 2003;31:890]. J Calif Dent Assoc. Nov 2003;31:817-823.
11. Walker L, Enciso R, Mah J. Three-dimensional localization of maxillary canines with cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2005;128:418-423.
12. Mah J, Enciso R, Jorgensen M. Ma-nagement of impacted cuspids using 3-D volumetric imaging. J Calif Dent Assoc. 2003;31:835-841.
13. Akdeniz BG, Grondahl HG, Magnus-son B. Accuracy of proximal caries depth measurements: comparison between limited cone beam computed tomography, storage phosphor and film radiography. Caries Res. 2006;40:202-207.
14. Aboudara CA, Hatcher D, Nielsen IL, et al. A three-dimensional evaluation of the upper airway in adolescents. Orthod Craniofac Res. 2003;6(suppl 1):173-175.
15. Ogawa T, Enciso R, Memon A, et al. Evaluation of 3D airway imagingof obstructive sleep apnea with cone-beam computed tomography. Stud Health Technol Inform. 2005;111:365-368.
16. Hatcher DC, Dial C, Mayorga C. Cone beam CT for pre-surgical assessment of implant sites. J Calif Dent Assoc. 2003;31:825-833.
17. Almog DM, LaMar J, LaMar FR, et al. Cone beam computerized tomography-based dental imaging for implant planning and surgical guidance, Part 1: Single implant in the mandibular molar region. J Oral Implantol. 2006;32:77-81.
18. Ganz SD. Conventional CT and cone beam CT for improved dental diagnostics and implant planning. Dent Implantol Update. 2005;16:89-95.
19. Moore WS. Cone beam C

]]> https://www.dentistrytoday.com/sp-824258800/ Sun, 01 Oct 2006 00:00:00 +0000 https://www.dentistrytoday.com/?p=11009 The growing popularity of cosmetic dentistry (or aesthetic dentistry), which often involves the preparation of multiple teeth, has emphasized the importance and necessity of provisional restorations. In order to fabricate high-quality provisional restorations, the clinician and technician should be familiar with different techniques and materials that are available. The evolution and introduction of improved products have significantly reduced the shortcomings of traditional provisional materials. This article provides an overview of different approaches to provisionalization, including an analysis of the advantages and disadvantages of the most commonly used techniques.
In the past, many clinicians did not emphasize the temporization phase of prosthetic dentistry, since provisional restorations were regarded as interim prostheses and both doctor and patient had low expectations. In spite of significant literature discussing the subject of provisional fabrication, the temporization step in the prosthetic treatment phase is often hastily performed.1
The primary objective of the provisional or transitional restoration is to provide protection for the prepared tooth and promote soft- tissue healing following trauma arising from tooth preparation and taking of the impression. In addition, it has been proposed that if a good periodontal state of health is established interproximally before the final restoration is constructed, and if this state of health is not disturbed during the construction of the restoration and exists on the day the restoration (transitional and/or final) is delivered to the patient, healthy soft-tissue interproximal papillae may be anticipated without loss of crestal bone.2-3
In terms of function, the provisional prosthesis should be carefully fabricated to protect the teeth from fracture; protect the pulp from thermal sensitivity and bacterial invasion; create proper embrasures, contacts, marginal extensions, and buccal and lingual contours; and maintain and stabilize maxillary and mandibular relationships by preventing tooth extrusion and drifting. While occlusal relationships should not be arbitrarily altered, the provisional restoration provides clinicians with a reversible opportunity to change vertical dimension and/or balance the occlusion to achieve a more appropriate result.4 In fact, the transitional prosthesis not only plays a crucial role serving as a guideline for the fabrication of the final restoration, it also offers a trial period to properly evaluate function, aesthetics, and phonetics in order to ensure that the final restoration satisfies the patient’s expectations as well as prosthetic and biological guidelines. In order to achieve an ideal final restoration, the clinician should take utmost care when approaching all steps of the procedure – diagnostic model, photography, wax-up, tooth preparation, shade selection, impression taking, material selection, provisionalization, final cementation, and post-delivery follow-up.

DIRECT PROVISIONALIZATION

The direct technique involves fabrication of the provisional restoration on the tooth preparation in the mouth. Within this context, there are many ways provisionals can be made by using the following materials/techniques: a commercially available clear tooth-form matrix, a prefabricated silicone stent based on the diagnostic wax-up, a polyvinyl siloxane (PVS) impression of the pre-preparation dentition, and provisional self-curing acrylic material, composite, or newer materials such as BIS-GMA composite. The various ways to make direct provisional restorations all involve different fabrication techniques and time, and provide different aesthetic results.
The simplest method is the one-step, single-mix technique, which requires the shortest time since only one material is used to fill the silicone stent before seating it over the preparations. Another method involves the use of a small amount of translucent/transparent material (flowable composite) in the incisal area only, and loading the rest of the stent with BIS-GMA composite before seating it over the preparation. A 2-step technique can also be used, which involves first loading the silicone index with a dentin-like material, pressing it onto the preparation, and letting it set before removal. The rough-stage provisional is then cut back to allow room for a second layer of transparent/translucent material such as flowable composite. If desired, custom stains can also be brushed onto the first layer to create a more aesthetic appearance before loading the incisal portion of the index with the second layer of material and seating again over the preparations.5
It is important at this step to give the patient a trial period to ensure his or her  comfort during the intermediate phase of treatment. Whatever technique is chosen, the clinician must take care to create a smooth finish to all margins of the provisional restorations, achieve appropriate embrasures and interproximal contacts, and check all functional occlusal contacts and excursive guidance/disclusion. Once the provisional restorations are ready for cementation or spot bonding, the preparations should then be thoroughly cleaned with Tubulicid Red (Global Dental Products), spot-etched, then brushed with an unfilled adhesive (but not light-cured until the provisionals are seated). Before the provisionals are cemented, they should be coated with a glazing agent to impart a natural luster as well as smoothness.
It is advisable to have the patient return in about 7 days to perform any necessary occlusal adjustment and refinement of the provisionals to the satisfaction of both the clinician and the patient. At this point, additional photographs should be taken of the provisionals at all angles – full-face, full-smile, retracted, lateral, and occlusal views. In addition, any necessary length and width measurements (eg, central incisors) and impressions of the provisionals should be taken so that accurate stone models of them can be made and sent along with the case to the ceramist. Indeed, the fabrication of accurate restorations depends upon the clinician’s ability to communicate clearly the specific biological parameters via impressions, photographs, wax-ups, models, and other forms of documentation.6 Not only do the resin provisionals represent the clinician’s attention to quality, they also provide a sense of security to the patient while waiting for the final restorations.7
Taking into account patients’ aesthetic demands, time concerns, and properties and cost of materials, the one-step technique using a transparent flowable composite in the incisal portion and a dentin-like material in the body offers advantages for cases involving multiple preparations (see next paragraph). With the availability of provisional materials such as Luxatemp (Zenith/DMG) in different shades (A1, A2, A3, A3.5, B1, and BL) and with improved physical and optical properties, a careful clinician should be able to fabricate excellent chairside provisionals that are both functional and aesthetic.

Advantages of Direct Provisionalization

• Protects the teeth from fracture.
• Protects the pulp from thermal sensitivity.
• Protects the pulp from bacterial invasion.
• Maintains gingival health through the design of abutments and pontics.
• Creates proper embrasures, contacts, marginal extension, and buccal and lingual contours.
• Maintains and stabilizes maxillary and mandibular relationship by preventing tooth extrusion and drifting.
• No laboratory fee.
• Interproximal access not necessary because multiple units are splinted together.

Disadvantages of Direct Provisionalization

• Possible pulpal irritation or damage if using self-curing acrylics.
• Requires greater clinical training and experience.
• Less flexural strength than indirect provisional restorations.

INDIRECT PROVISIONALIZATION

In the past, without the availability of new direct provisional materials with enhanced physical properties, many clinicians preferred the indirect technique in cases involving multiple teeth and/or complex and lengthy treatment. However, with today’s technology and the availability of state-of-the-art direct provisional materials, the longstanding advantages of the indirect techniques no longer outweigh the disadvantages.
The indirect technique mainly involves laboratory- fabricated provisionals based on pre-preparation models or wax-ups. However, since the marginal fit of the provisional restorations are based on simulated preparations on study models, the restorations must be relined and adjusted at chairside. In addition, custom staining and recontouring may still be necessary.

Advantages of Indirect Provisionalization

• High flexural strength.
• Excellent aesthetics.
• Minimal risk of pulpal irritation or damage.
• Longer functional use.
• Less demanding on the clinician.

Disadvantages of Indirect Provisionalization

• Additional laboratory cost.
• Special equipment required (an oven is needed if belleGlass indirect [KerrLab], Tescera [Bisco], or Gradia Micro Ceramic Indirect System [GC America] is used).
• Second appointments needed.
• Time constraints.

CAD/CAM PROVISIONALIZATION

Another method to fabricate a long-term provisional restoration involves CAD/CAM technology. One such approach is the CEREC system (Sirona). The latest version, the CEREC 3D, has enabled clinicians to fabricate aesthetic and durable restorations from machinable ceramic (Vita [Vident] or ProCad [Ivoclar Vivadent]) or composite (3M ESPE) blocks.8 In cases involving one central incisor (either vital or nonvital), the ability to custom stain a porcelain provisional restoration allows the clinician to provide an excellent provisional restoration that not only pleases the patient, but also offers the ceramist and clinician important information regarding value, chroma, and degree of translucency in order to be able to produce a mirror image of the contralateral central incisor.

Advantages of CAD/CAM Provisionalization

• High strength.
• Very long-lasting.
• Choice of composite or porcelain materials.
• No pulpal irritation.
• Excellent aesthetics.
• Provides more information to clinician and ceramist.

Disadvantages of CAD/CAM Provisionalization

• High cost of equipment.
• Additional training required (to operate manufacturing machine).
• Not practical for multi-unit restorations.

CASE PRESENTATIONS

Case 1

Figure 1. Preoperative view demonstrates anterior incisal fractures.	Figure 2. Anterior view of the preparation of tooth No. 9.

Figure 3. Provisional was fabricated with Luxatemp Fluorescence.

The patient, a 50-year-old Caucasian in good health, presented with a major complaint of a compromised appearance of his maxillary central incisors (Figure 1).
History revealed nocturnal grinding and a previous habit of chewing on pencils. Different treatment modalities, inherent costs, advantages, and disadvantages were presented to the patient, and he elected to have an indirect porcelain veneer placed on tooth No. 9 and composite restoration on tooth No. 8. Alginate impressions and bite registration were then taken for a diagnostic model and wax-up, a silicone stent (for provisional fabrication), and custom tray (for taking an impression). Digital photos were also taken for shade mapping,  since it is challenging to fabricate a single veneer on a central incisor.
On the day of tooth preparation, Citanest Plain and Xylocaine (both DENTSPLY Pharmaceutical) with 1:100,000 epinephrine were used for local anesthesia. The teeth were then conservatively prepared for a composite restoration on tooth No. 8 and a porcelain veneer on tooth No. 9 (Figure 2). Once the composite on tooth No. 8 was completed, retraction cords immersed in Hemodent (Premier Dental) were placed, and a PVS impression was made. Photos of the stump shade were taken as well as a bite registration with Blu-Mousse (Parkell). The silicone stent was then loaded with Luxatemp Fluorescence (Figure 3) and seated in the mouth. After recontouring and polishing, Kolor + Plus color modifier (Kerr Dental) was applied and light-cured, and a final layer of Premise Super Clear composite (Kerr Dental) was added and light-cured. Normally, unless the case involves an aesthetically challenging area, the use of Luxatemp Fluorescence alone can yield excellent provisional restorations.
After final polishing, the preparation was then cleaned with Tubulicid Red and spot-etched with 37.5% phosphoric acid (Gel Etchant [Kerr Dental]) for 15 seconds. Following rinse, Prime & Bond NT (DENTSPLY Caulk) was applied on both the preparation and the internal surface of the provisional, and the provisional was then seated and light-cured for 60 seconds. After routine cleanup and adjustment, more photos were taken with and without a custom-fabricated shade tab (made during previous visit). Alginate impressions were then taken for reference as well as for the fabrication of a maxillary splint to address the grinding habit and protect the dentition and restorations. The patient was then given home care instructions, including emphasis on meticulous care of the gingival tissue in the area of tooth No. 9 to prevent possible changes in the soft-tissue architecture, which would then compromise the result.

CASE 2

The patient, a 30-year-old African American, sought improvement in the appearance of her teeth and smile. Her health was very good, and she had no known allergies. Because of the severity of the overbite, the misalignment of her anterior teeth, and the multiple diastemas, orthodontic treatment was recommended. However, since the patient was soon to be married, she decided against orthodontic treatment. Taking into account all diagnostic data, an osseous crown lengthening procedure was recommended before fabrication of the anterior veneers. Impressions were taken for a surgical stent, diagnostic wax-up, silicone provisional stent, custom trays, and case presentation. Once healing was complete (approximately 6 weeks after periodontal surgery), the patient was ready for the prosthetic phase, which included 8 porcelain veneers from teeth Nos. 5 to 12.
The procedure was reviewed and consent forms were signed, then the patient was anesthetized with Cita-nest Plain and Xylocaine with 1:100,000 epinephrine. The tooth preparations were completed with subgingival interproximal margins to allow for proper emergence profile of the veneers. The silicone stent was then loaded with Luxatemp Fluorescence and was seated in the mouth. The provisionals were then contoured and checked for appearance and fit. Using the provisionals for guidance, the interproximal gingiva was shaped with a diode laser. Retraction cords were then placed, the preparations refined, and an impression was taken with a PVS material (Aquasil Ultra  [DENTSPLY Caulk]).
A face-bow transfer was then made, and a stick bite and posterior bite were taken with Blu-Mousse. Photos of stump shades and the stick bite were also made. The provisionals were finished, polished, silanated with silane primer (Kerr Dental), and coated with Prime & Bond NT. The preparations were then cleaned with Tubulicid Red, spot-etched with 37.5% phosphoric acid Gel Etchant  for 15 seconds, rinsed, and dried. The same adhesive was also applied onto the preparations. A thin layer of Filtek Supreme Plus Flowable Restorative (3M ESPE) was applied onto the internal surface of the provisionals before luting. Following tack-curing with a curing light, excess composite was removed with a scaler and a Bard-Parker blade No. 15C. Following final adjustment and shaping with finshing burs, Kolor + Plus color modifiers were selectively applied with a sable brush and light-cured before a final layer of glaze was applied and light-cured. The occlusion and all excursive movements were checked, home care instructions for the provisionals as well as gingival tissue were given, and photos were taken.
The patient was then rescheduled for a follow-up visit during which any necessary modifications are made to ensure that the patient will be happy with the final shape, contour, and shade of the veneers. Once the approval form was signed and dated, alginate impressions of both arches were taken for the fabrication of the veneers. When the veneers were delivered, a maxillary splint was fabricated to protect them.

CONCLUSION

Figure 4. Smile – before.	Figure 5. Retracted view – before.

Figure 6. Smile with provisional restorations.

Depending on the complexity of the case, the clinician should choose the proper technique to provisionalize the tooth preparations. Selection of provisional materials is based on such factors as the time the provisionals will be in the mouth, aesthetic concerns, and patient expectations. In the majority of cases that involve a major change in appearance, provisional restorations should be made to reflect accurately the form, contour, color, and transparency of the final restorations. The only difference between the provisionals and the final restorations should be the material from which they are fabricated. With currently available materials and techniques, there is no need to compromise the appearance and fit of the provisional restorations (Figures 4 to 6).
Considering the enhanced physical and aesthetic properties of many direct provisional restorative materials currently available, once a treatment plan has been developed, in most cases provisionalization can be executed at chairside using direct techniques.

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References

1. Liebenberg WH. Direct pressure provisionalization technique: a new open-tray technique for complete-arch rehabilitations. Quintessence Int. 2000;31:83-93.
2. Liebenberg WH. Reducing marginal flash in the fabrication of direct provisional restorations: a new technique using light-cured resin and transparent silicone. J Can Dent Assoc. 1995;61:708-713.
3. Nevins M. Interproximal periodontal disease: the embrasure as an etiologic factor. Int J Periodontics Restorative Dent. 1982;2:8-27.
4. Rossein K. Provisionalization: the key to cosmetic & restorative success. Compend Contin Educ Dent. 1995;16:684-688.
5. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Carol Stream, Ill: Quintessence; 2002; 280-289.
6. Massironi D, Romeo G. Provisionalization as a communication parameter for definitive restoration. Pract Proced Aesthet Dent. 2002;14:301-305.
7. Rufenacht CR. Fundamentals of Esthetics. Chicago, Ill: Quintessence; 1990; 189-210.
8. Hehn S. The evolution of a chairside CAD/CAM system for dental restorations. Compend Contin Educ Dent. 2001;22(suppl 6):4-6.

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Dr. Le maintains a private practice in Port Arthur, Tex, with an emphasis on aesthetic dentistry and implant dentistry. He is a Fellow of the Inter-national Congress of Oral Implantologists. Dr. Le can be reached at (409) 982-7827 or tmldds@gt.rr.com.

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Continuing Education Test No. 82.1

 

After reading this article, the individual will learn:

• advantages and disadvantages of direct and indirect provisionalization, and
• clinical technique for provisionalization.

1. What is the main objective of the provisional restoration?

a. to provide an aesthetic appearance for the patient
b. to provide protection for the prepared tooth or teeth
c. to promote soft-tissue healing
d. b and c

2. With provisional restorations, the clinician should ____.

a. always change occlusal relationships according to his or her philosophy and training
b. never alter the patient’s existing occlusal relationships
c. rely on the laboratory technician to determine the final occlusal scheme
d. consider altering the patient’s occlusal relationships to achieve a more balanced occlusion

3. In a multi-unit case, a clinician should only proceed to the delivery of the final restorations ____.

a. after the patient  has made full payment for the services
b. as soon as possible after the preparation and provisionalization appointment
c. after seeing the patient again to evaluate the provisionals in terms of aesthetics, function, and phonetics
d. after having discussed the case with the laboratory technician

4. The direct provisionalization technique may involve ____.

a. the use of a single layer of material
b. the use of a multilayered mix of materials including custom stains
c. cutting back the first layer of material to allow room for a second layer of more translucent material
d. all the above

5. Before sending a multi-unit case to the lab for final fabrication, the clinician should ___.

a. take photos of the provisionals and the patient
b. enclose the diagnostic wax-up with the case
c. have photographs and a model made from provisional restorations in the patient’s mouth, accurate measurements of length and width of the involved teeth, and a detailed laboratory prescription
d. not do anything else since the provisionals look good to both the clinician and the patient

6. What is NOT an advantage of direct provisionalization?

a. creating proper buccal and lingual contour
b. no laboratory fee
c. maintaining and stabilizing occlusal relationship
d. requiring greater clinical ability and training

7. What is a disadvantage of indirect provisionalization?

a. It is less demanding on clinician’s skills and training.
b. There is minimal risk of pulpal irritation.
c. It may require special equipment.
d. The aesthetic result.

8. The clinician should take this/these factor(s) into account when considering a provisionalization technique:

a. material properties
b. cost of material
c. length of time the provisionals will be in the mouth
d. a and c

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To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 82.1), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).

 

]]> https://www.dentistrytoday.com/sp-600573044/ Sun, 01 Oct 2006 00:00:00 +0000 https://www.dentistrytoday.com/?p=10987 Tissue engineering is defined as any attempt to facilitate regeneration of tissues in the body by combining appropriate biologic mediators and matrices.1 Many procedures performed by periodontists are included under this definition. Soft-tissue grafting procedures, periodontal regenerative procedures, and surgical procedures with the administration of recombinant growth factors or amelogenin-like factors fall within the definition of tissue engineering.2 The surgical wound contains a scaffold of cells and signaling molecules.3 In the appropriate environment with an adequate blood supply and control of both bacterial contamination and other environmental factors, regeneration of the periodontium can be achieved (Figure 1).4 By understanding the biologic principles of wound healing and regenerative medicine, clinicians can optimize the results of these procedures.
Advances in regenerative techniques are revolutionizing periodontal therapy. Periodontics once relied on resective techniques to establish periodontal health. These techniques often result in aesthetic deformities, with long clinical crowns, receded gingival tissues, and increased risk for root sensitivity and root caries. Periodontics now utilizes regenerative techniques to offer surgical approaches that actually conserve tissue contour and aesthetics. The combination of newer procedures and biologically active materials to stimulate the regenerative response is changing the approach and patient outcomes of periodontal treatment.

Figure 1. This grade II furcation defect was successfully treated with the growth factor rhPDGF-BB delivered in an allogeneic matrix, as evidenced by the histologic results. Note new bone (NB), new cementum (NC), and periodontal ligament (PDL). (Image reprinted with permission of the Journal of Periodontology.)

One must combine the latest technologies with surgical advances to improve patient care. The introduction of the connective tissue graft 20 years ago allowed periodontists to provide patients with excellent functional and aesthetic results.5 It has been documented in the literature that this is a highly predictable procedure and is the standard of care for root coverage therapy.6 Even with advanced root exposure, current advances like the implementation of techniques such as modified double pedicle flap design and amelogenin-like factors can significantly enhance grafting procedures.7,8 The goal of these advances is to provide root coverage that will be stable over time and will meet the aesthetic goal of not being easily identified as having been surgically treated.
Currently, in clinical practice a high percentage of oral plastic surgical procedures can benefit from the use of amelogenin-like factors or growth factors to enhance therapeutic results. These include periodontal regeneration procedures, root coverage with connective tissue grafting, socket preservation, and implant site development with ridge grafting or sinus grafting. These procedures can either apply new therapeutic biomaterials as a novel therapy or utilize growth factors as an adjunctive agent to enhance a current technique. The following cases demonstrate the utilization of regenerative therapies with tissue engineering.

CASE 1

This patient presented with a maxillary right canine with advanced gingival recession that was treated with a free gingival graft approximately 15 years ago (Figure 2a). The graft was successful in preventing further gingival recession but did not meet the patientÃs aesthetic needs. She had a high smile and was concerned with the visible recession presenting on both maxillary canines.
The use of a connective tissue graft combined with a modified double pedicle technique, enamel matrix derivative (EMD [Straumann]), and a coronally advanced flap offered a predictable treatment option.
The site was treated by surgically accessing the dehisced root surface (Figure 2b). The root surface was aggressively root planed with hand instruments, and any previously placed composite restoration was removed. The root surface was œconditioned” with tetracycline prior to and a topical, neutral root surface conditioner (PrefGel [Straumann]) after root planing. A connective tissue graft was harvested from the maxillary right palate. Primary closure of the donor site was attained. EMD was applied to the cleaned and dried root surface, to the recipient surgical site, and also to the palatal wound.

Figures 2a and 2b. A high smile line and clefting of the gingiva present an aesthetic challenge. The osseous defect is exposed.

Figures 2c and 2d. The root surface is treated with tetracycline paste, EMD, and a connective tissue graft. The cleft of receded gingiva is repaired with 7-0 polypropylene sutures.

Figure 2e. At 1-year postoperatively there is near total root coverage and a very good aesthetic result.

The connective tissue graft was sutured at the level of the CEJ using sling sutures (6-0 chromic gut) with the knots tied on the palate to keep them away from the graft. The repaired buccal flap was then coronally advanced to achieve primary closure over the graft, and sutured tension-free with sling sutures and interrupted sutures at the vertical incisions (Figures 2c and 2d).
Six months postoperatively a gingivoplasty was performed to smooth the area of the old free gingival graft. Although the high smile created a high aesthetic demand for this patient, the 12-month postoperative result showed excellent root coverage and good aesthetic blending of the tissues (Figure 2e). There was little sign of the previous graft with this biomimetic therapy. The maxillary left canine was also successfully treated with a connective tissue graft.

PERIODONTAL REGENERATION

The most challenging aspect of periodontal treatment is regenerating the periodontium – including alveolar bone, periodontal ligament, and cementum – on a previously diseased root surface. Recently the Food and Drug Administration approved a recombinantly engineered growth factor delivered in a synthetic matrix. GEM 21S (Osteohealth) has been shown in a randomized, controlled, double-blind clinical trial to increase clinical attachment and to increase linear radiographic bone growth and percent radiographic bone fill at 6-month post-treatment evaluations.9 GEM 21S combines a potent, periodontally targeted growth factor (rhPDGF-BB) with a synthetic beta tricalcium phosphate (B-TCP) matrix to allow for the regeneration of lost periodontal tissues. Over the past 20 years rhPDGF-BB has been extensively researched for this application and has been shown to be extremely safe. In 2 multicenter studies including a 6-month clinical trial with 120 patients receiving the rhPDGF-BB therapy, there were no serious adverse events related to treatment.10

CASE 2

Figures 3a and 3b. A regenerative membrane is difficult to keep covered when placed over a dehisced defect. This site was treated with B-TCP pre-soaked in rhPDGF-BB.

Figure 3c. Radiograph at 36 months shows evidence of bone maturation and stability of the site.

This patient was diagnosed with aggressive periodontitis and presented with a mandibular right canine with advanced periodontal bone loss. Surgical exposure of the site revealed a 7-mm intrabony defect (Figure 3a). The defect was 1-wall/2-wall and was not well-contained. Traditional approaches with guided tissue regeneration (GTR) would have presented a challenge for managing the soft tissues over the regenerative membrane, and membrane exposure can significantly reduce the success of GTR.
This patient was treated as part of a clinical trial with 1.0 mg/mL of rhPDGF-BB combined with B-TCP. Great care was taken during the surgery to gently elevate the soft tissues and provide a flap with adequate access to remove granulomatous tissue and debride the root surface of calculus. The root surface was conditioned by placing topical tetracycline paste for 4 minutes. Treatment with rhPDGF-BB was applied directly to the cleaned and dried root surface and the defect. The B-TCP was pre-soaked in the rhPDGF-BB and then applied to fill the defect (Figure 3b). The flaps were sutured for primary closure over the defect.
At 12 months, there was radiographic suggestion of bone fill, and re-entry surgery revealed apparent bone fill of the defect and coverage of the previously dehisced buccal root surface. The postoperative radiograph suggested maturation of the treated site, and the 36-month postoperative radiograph evidenced further maturation and stability (Figure 3c).

CASE 3

Figure 4a. Radiograph of mandibular second molar with 11-mm pocket on distal-buccal surface. In Figures 4a and 4b, note the bone trabeculation with the inverted radiographic image.	Figure 4b. Radiographic evidence of bone fill with trabeculation at 3 years following treatment with 0.3 mg/mL rhPDGF-BB and B-TCP (GEM 21S).

This patient’s mandibular left second molar presented with an 11-mm periodontal pocket on the distal-buccal surface and was treated with GEM 21S (0.3 mg/mL rhPDGF-BB and B-TCP) during the clinical trial (Figure 4a). The preoperative radiograph evidenced a deep vertical defect on the distal surface approaching the apical one third of the distal root. This tooth had a guarded prognosis, but the patient wanted to save it. Evaluation 6 months postoperatively revealed there was a 6-mm reduction in probing depth and a 6-mm gain of clinical attachment. The 3-year postoperative radiograph evidenced bone fill with natural trabeculation and no sign of the original defect (Figure 4b). This tooth now has a good prognosis and has been restored with a full-coverage restoration.

CASE 4

Figures 5a and 5b. The baseline and 2.5-year radiographs of mandibular incisors treated with DFDBA and EMD indicate recalcification of the defect.

This patient presented with generalized advanced chronic periodontitis (AAP type IV) and had been previously told that her mandibular incisors would require extraction due to advanced periodontal bone loss. The treatment options presented to the patient were either to extract the 4 mandibular incisors and replace them with an implant-supported fixed partial denture, or to utilize periodontal regenerative therapy to maintain the incisors. The patientÃs desire was to save her natural teeth, which determined the treatment plan.
Initial therapy included scaling and root planing, oral hygiene instruction, and occlusal analysis. The occlusal analysis identified the need to control the mobility of the incisors, which was accomplished with occlusal adjustment and provisional splinting with wire mesh and composite resin.
Surgical debridement revealed a 1-wall defect between teeth Nos. 23 and 24. The roots were conditioned sequentially – first with tetracycline prior to root planing and then with neutral pH EDTA prior to applying the EMD gel to the cleaned and dried root surface. The site was treated with a combination therapy: 75% demineralized freeze-dried bone allograft (DFDBA), 25% particulate autogenous bone graft, EMD, and a protective collagen membrane (Bio-Gide  [Osteohealth]). The EMD was mixed with the graft and applied over the graft, the membrane, and the surgical wound.
The 4-month postoperative radiograph was suggestive of bone fill, and the 9-month radiograph evidenced recalcification of the treated site. The 30-month postoperative radiograph demonstrates normal trabeculation of the treated site (Figures 5a and 5b). To straighten the mandibular incisors, the patient desires orthodontic treatment, which will be considered after the 36-month evaluation.

CASE 5

Figures 6a and 6b. An 11-mm defect with improved prognosis 3 years after regenerative treatment.

This patient presented initially with an 11-mm defect on the mesial surface of his mandibular left first molar. The 3-year radiographic evaluation after combination regenerative periodontal therapy with a bone replacement graft, growth factor, and absorbable membrane reveals a tooth with an improved prognosis. There is significant bone fill of the original defect (Figures 6a and 6b).

CASE 6

Figures 7a to 7e. A more complex case involves a mucogingival defect, gingival recession, and grade II furcation involvement and is treated with a combination of EMD, DFDBA, a connective tissue graft, and a modified double pedicle technique.  At 1 year there is 10 mm of attachment level gain and an adequate zone of attached gingiva.

More complex problems can be addressed by combining hard- and soft-tissue regenerative procedures. For example, this case presented with a maxillary left first molar with a mucogingival defect, gingival recession, and grade II furcation invasion (Figures 7a to 7e).
The defect site was treated with EMD combined with DFDBA, a connective tissue graft, and a modified double pedicle technique. After flap elevation, degranulation, and root preparation the defect was treated with EMD and then filled with DFDBA hydrated with and pre-soaked in EMD. The connective tissue was then sutured over the bone graft. The overlying flap, which presented with clefting, was repaired with 7-0 polypropylene sutures maintaining the papilla to the original position. A periosteal releasing incision allowed for primary closure over the composite graft. The 12-month clinical evaluation revealed an adequate zone of attached gingiva and approximately 10 mm of attachment gain.

CONCLUSION

The advances that tissue-engineered regenerative medicine is bringing to periodontology are very exciting for researchers, clinicians, and patients. Decades of research has resulted in improved patient care as assessed by clinical and radiographic outcomes. Because of the success of osseointegrated implants, many teeth are being extracted that could be restored to health with current periodontal therapy. It is imperative that clinicians consider all options for therapy, including regenerative periodontics, prior to extracting teeth. Clinicians must communicate these options to their patients.

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References

1. Langer R, Vacanti JP. Tissue engineering. Science. 1993;260:920-926.
2. Lynch SE. The role of growth factors in periodontal repair and regeneration. In: Polson AM, ed. Periodontal Regeneration: Current Status and Directions. Chicago, Ill: Quintessence; 1994:179-198.
3. Giannobile W. Periodontal tissue regeneration by polypeptide growth factors and gene transfer. In: Lynch SE, Genco RJ, Marx RE, eds. Tissue Engineering: Applications in Maxil-lofacial Surgery and Periodontics. Chicago, Ill: Quintessence; 1999.
4. Camelo M, Nevins ML, Schenk RK, et al. Periodontal regeneration in human Class II furcations using purified recombinant human platelet-derived growth factor-?? (rhPDGF-BB) with bone allograft. Int J Periodontics Restorative Dent. 2003;23:213-225.
5. Langer B, Langer L. Subepithelial connective tissue graft technique for root coverage. J Periodontol. 1985;56:715-720.
6. Wennstrom JL. Mucogingival therapy. Ann Periodontol. 1996;1:671-701.
7. Harris RJ. The connective tissue with partial thickness double pedicle graft: the results of 100 consecutively-treated defects. J Periodontol. 1994;65:448-461.
8. Rasperini G, Silvestri M, Schenk RK, et al. Clinical and histologic evaluation of human gingival recession treated with a subepithelial connective tissue graft and enamel matrix derivative (Emdogain): a case report. Int J Periodontics Restorative Dent. 2000;20:269-275.
9. Nevins M, Giannobile WV, McGuire MK, et al. Platelet-derived growth factor stimulates bone fill and rate of attachment level gain: results of a large multicenter randomized controlled trial. J Periodontol. 2005;76:2330-2332.
10. Howell TH, Fiorellini JP, Paquette DW, et al. A phase I/II clinical trial to evaluate a combination of recombinant human platelet-derived growth factor-BB and recombinant human insulin-like growth factor-I in patients with periodontal disease. J Periodontol. 1997;68:1186-1193.

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Dr. Nevins is in the private practice of periodontics and implant dentistry in Boston. He is a Diplomate of the American Board of Periodontology and is an Assistant Clinical Professor in the Department of Periodontology at Harvard School of Dental Medicine. Dr. Nevins graduated from Tufts University School of Dental Medicine and received his certificate for graduate training in periodontology and a master of medical sciences in oral biology at Harvard School of Dental Medicine. He has research interests in clinical applications of tissue engineering for periodontics and implant dentistry. He can be reached at marc_nevins@hms.harvard.edu.

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Continuing Education Test No. 82.2

After reading this article, the individual will learn:

Ô how tissue engineering can improve clinical periodontal outcomes, and
Ô to recognize clinical applications for using amelogenin-like factors and growth factors to enhance the outcome of periodontal therapy.

 

1. Tissue engineering can achieve regeneration of tissues using ____.

a. scaffolds
b. cells
c. signaling molecules
d. all of the above

2. Periodontal regeneration is documented histologically by observation of which tissues adjacent to the previously diseased root surface?

a. cementum
b. periodontal ligament
c. alveolar bone
d. all of the above

3. B-TCP is used ____.

a. as an anticoagulant
b. as a synthetic matrix in combination with a growth factor
c. as a post-surgical dressing
d. in suture materials

4. rhPDGF-BB is ____.

a. a bone grafting material
b. a periodontally targeted growth factor
c. a solution used to treat root sensitivity
d. an anticoagulant

5. The connective tissue graft for root coverage as presented by Langer and Langer ____.

a. uses a free keratinized soft-tissue graft for root coverage
b. uses free keratinized soft-tissue graft to enhance the zone of attached gingiva
c. uses a connective tissue graft protected by the primary flap to achieve root coverage
d. uses growth factors to enhance the healing

6. Regenerative treatment can be used to treat the following types of defects ___.

a. recession
b. intrabony defects
c. furcation defects
d. all of the above

7. GEM 21S combines the following to treat periodontal defects ____.

a. allogeneic cells and bone
b. beta tricalcium phosphate and tetracycline
c. rhPDGF-BB and allogeneic bone
d. beta tricalcium phosphate and rhPDGF-BB

8. Regenerative procedures utilizing newer technologies such as amelogenin-like factors and growth factors require detailed attention to ____.

a. root debridement
b. flap management
c. postoperative oral hygiene
d. all of the above

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To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 82.2), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).

]]> https://www.dentistrytoday.com/sp-660000750/ Fri, 01 Sep 2006 00:00:00 +0000 https://www.dentistrytoday.com/?p=10742 The use of hydrogen peroxide in dentistry can be traced back more than 100 years.^1-4 Initially, hydrogen peroxide was evaluated for use in periodontal treatment and wound healing. Studies have substantiated that hydrogen peroxide can prevent and delay the colonization and replication of anaerobic bacteria.^5,6 This reduction in the microflora, with subsequent reduction in the levels of plaque accumulation, resulted in better gingival health.⁷ Furthermore, wound healing following periodontal surgery was enhanced as a result of the antimicrobial effects of topically administered hydrogen peroxide.⁸
Bleaching agents are compounds that are used to remove color from substances, and most are oxidizing agents such as hydrogen peroxide, which are effective in decolorizing substances via oxidation. The decolorizing action of bleaches is due in part to their ability to remove electrons, which are activated by visible light to produce various colors.⁹ In 1966 Schneider, et al¹⁰ documented the use of a peroxide-containing gingival strip to apply peroxide to healing periodontal tissues. Tooth whitening was later observed as an unintentional side effect when hydrogen peroxide was used in periodontal treatment.¹¹ In the late 1960s Klusmier noticed the whitening effect when using Gly-Oxide (GlaxoSmithKline) in orthodontic positioners.¹² Later, Wagner used Proxigel (Reed and Carnrick Pharmaceutical) in custom-fitted vacuum-formed trays specifically for tooth whitening. These were FDA-approved oral antiseptics containing 10% carbamide peroxide.¹³
In 1989, Heymann and Haywood published a report that introduced the concept of using a nightguard with a viscous whitening solution that contained a thickening agent (Carbopol). The viscosity of the solution allowed for a longer bleach time and increased retention in the tray.¹⁴ In 1989 Fischer, who created Opalescence carbamide peroxide (Ultradent Products), received a patent for a thick and sticky whitening gel formulation that is still the basis for most night-time gels in use today. Carbamide peroxide breaks down into hydrogen peroxide and urea; hydrogen peroxide breaks down into oxygen and water; urea breaks down into ammonia and carbon dioxide. This was the first ADA-approved system for whitening.¹³ This product was developed with a high water content to minimize tooth sensitivity, a neutral pH, a thixotropic viscosity to improve retention in the tray, and sustained release of the hydrogen peroxide. With this introduction of home whitening, there has been explosive growth in consumer awareness and use of tooth-whitening systems. There are literally hundreds of competing products and delivery systems for in-office and home use. However, all systems employ the basic principles of exposing the discolored dentition to various forms of hydrogen peroxide over time.
The safety of hydrogen peroxide and carbamide peroxide has been documented in numerous studies. Haywood and Heymann¹⁵ evaluated vital bleaching using 10% carbamide peroxide in a nightguard, stating that concerns of toxicity or damage to hard and soft tissues appear unfounded. In a retrospective review of the medical and dental literature Yarborough¹⁶ states that the safety and efficacy of hydrogen peroxide is well-established. Hydrogen peroxide does not adversely affect enamel morphology or microhardness, and it is not expected to inhibit pulpal enzymes.¹⁷ Even when used for extended periods of time when treating tetracycline-stained teeth, no adverse effects have been noted using carbamide peroxide.18

EXTRINSIC AND INTRINSIC STAINS

Figure 1. A 45-year-old male demonstrating tetracycline staining and a nonvital tooth No. 9. (Figures 1 to 9 are courtesy of Dr. Bruce Matis.)	Figure 2. The patient after 4 months of take-home whitening.

Figure 3. Three months post bleaching.

Dental discoloration can be due to extrinsic staining, which is superficial and affects only the enamel surface. This type of discoloration is associated with the use of tea, coffee, chewing tobacco, some foods such as blueberries, and red wine. In addition, teeth discolor in association with aging. This type of discoloration is relatively easy to treat with tooth whitening. The intrinsic stains that discolor the tissues of the tooth (enamel, dentin), such as that related to fluorosis or tretracycline (Figures 1 to 3), are much more difficult to treat. Even though peroxides in whitening systems have been shown to rapidly permeate intact enamel, dentin, and pulp,¹⁹ changing the color of the dentin requires long exposure to produce any noticeable effect. Hydrogen peroxide releases oxygen that breaks down conjugated bonds in protein chains associated with stain into a single bond. This results in more absorption of color wavelengths, resulting in the reflection of little color (ie, a whitening effect).²⁰

IN-OFFICE WHITENING

In-office tooth whitening is associated with a higher cost than take-home whitening systems due to chair time. In-office whitening is best for those patients who desire a quick result and for those who need close monitoring for clinical conditions such as pronounced gingival recession or deep, unrestored abfraction lesions. It is also necessary for tooth discoloration associated with endodontic therapy. In-office tooth whitening using high concentrations of hydrogen peroxide is not new. Boksman, et al published articles in the 1980s on the use of heated Superoxol (Sultan Healthcare) hydrogen peroxide (30%).^21-24
Many current systems use light activation in conjunction with hydrogen peroxide. Examples include the following: LaserSmile (Biolase Technology) 37% hydrogen peroxide; ArcBrite (Biotrol) 30% hydrogen peroxide; Brite-Smile (BriteSmile) 15% hydrogen peroxide; Rembrandt Lightning Plus (Johnson & Johnson) 35% hydrogen peroxide; Zoom (Discus Dental) 20% hydrogen peroxide; and LumaWhite Plus (LumaLite) 35% hydrogen peroxide. Because of media coverage about light-activated bleaching, patient demand for this process is increasing. It is interesting to note that clinical trials repeatedly show that light and heat do not increase the efficacy of tooth whitening and are not necessary for vital tooth bleaching. Contact time and concentration of active ingredients are the critical factors.²⁵
Light-activated whitening systems offer a marketing opportunity but add cost, occupy operatory space, can cause burning of the soft tissue, and can increase operatory temperature.²⁶ All systems recommend a take-home tray as an adjunct, so the question is whether any observed benefit is due to the light or the tray.²⁷ It is also important to note that many drugs patients may be using cause minor to marked photosensitivity and hyperpigmentation. These include acne medications, anticancer drugs, antidepressants, antihistamines, antimicrobials, anti-parasitic drugs, antipsychotic drugs, diuretics, hypogly-cemics, and nonsteroidal anti-inflammatory drugs.²⁸ Therefore, the use of a light for in-office whitening may not be justified due to the risks involved.

Figure 4. Preoperative photograph of 46-year-old female requesting in-office whitening.	Figure 5. Opalescence Xtra Boost gel on teeth, with OpalDam (Ultra-dent Products) protecting the gingival tissues and covering the gingival margin of the tooth by 0.5 mm.

Figure 6. After three, 15-minute applications of Opalescence Xtra Boost (at one appointment).

In-office whitening systems not using light or heat include the following: Illumin with 15% hydrogen peroxide (DENTSPLY Professional) OfficeWhite with 40% hydrogen peroxide (Life-Like Cosmetic Solutions); Perfection White with 35% hydrogen peroxide (Premier Dental Products); Niveous with 25% hydrogen peroxide (Shofu Dental); and Opalescence Xtra Boost (Ultradent Products) with 38% hydrogen peroxide (Figures 4 to 6). Due to the adverse effects these high concentrations of hydrogen peroxide can have on the gingival tissues, many of these systems utilize various forms of tissue protection to minimize the potential for damage. The time of application and number of applications vary by product.

TAKE-HOME WHITENING

Figure 7. Prewhitening.	Figure 8. Same patient after whitening maxillary dentition with 10% Opalescence.
Figure 9. Same patient after whitening the mandibular arch.	Figure 10. Trèswhite with 9% hydrogen peroxide gel and an outer gingival protector gel.

At-home systems for tooth whitening, utilizing tray delivery of the whitening agent, have been extensively studied since their introduction by Heymann and Haywood¹⁴ (Figures 7 to 9). The degradation of carbamide peroxide occurs over time. After 2 hours, more than 50% of the active agent is available, and 10% is available after 10 hours.²⁹ Therefore, for use at night, the maximum whitening effect occurs in the first 2 hours. Whitening agents that are recommended by their manufacturers for night-time use include the following: Opalescence PF (Ultradent Products) 10%, 15%, and 20% carbamide peroxide; Nupro White Gold (DENTSPLY Professional) 10% and 15% carbamide peroxide; Nite White Turbo (Discus Dental) 6% hydrogen peroxide; and Pola-Night (Southern Dental In-dustries) 10%, 16%, and 22% carbamide peroxide.
For daytime use, both carbamide peroxide and hydrogen peroxide are effective at-home bleaching agents.³⁰ Products indicated by their manufacturers for daytime use include the following: Opalescence PF 10%, 15%, and 20% carbamide peroxide; Rembrandt XTRA-Comfort (Johnson & Johnson) 16%, 22%, and 30% carbamide peroxide; Natural Elegance (Henry Schein) 10%, 15%, and 22% carbamide peroxide; JustSmile (JustSmile Whitening Systems) 2% to 10% hydrogen peroxide; Perfecta Brav (Premier Dental Products) 9% hydrogen peroxide; and PolaDay (Southern Dental Industries) 3%, 7.5%, and 9.5% hydrogen peroxide.

A product recently introduced by Ultradent Products is Trèswhite. The inner tray, containing 9% hydrogen peroxide gel, has a gingival barrier protector gel around the sides. This prefabricated system utilizes an outer overtray, which carries the inner tray to the mouth and is then removed, leaving the inner tray containing the bleaching material adapted to the teeth (Figure 10).

The effects of hydrogen peroxide and carbamide peroxide on enamel have been extensively studied. Araujo, et al looked at the effect of 10% carbamide peroxide on the microhardness of human enamel and found that bleaching with carbamide peroxide is safe for human enamel.³¹ When evaluating peroxide bleaching on enamel surfaces, White, et al found that there was no decrease in surface hardness measurements associated with tooth bleaching.³² Clark looked at the application of fluoridated 10% carbamide peroxide on enamel and found demineralization inhibition comparable to toothpaste of similar fluoride concentration.³³ In a recent study by Al-Qunaian, Opalescence PF 20% showed an enamel surface that was less susceptible to caries than the control.³⁴ However, when looking at the effects of 7 carbamide peroxide bleaching agents on enamel microhardness over time, Basting found that enamel treated with different bleaching agents or a placebo experienced a similar decrease in microhardness values over time, with the exception of (enamel) fragments exposed to Opalescence PF 20%.³⁵

 

Figure 11. Application of LC Block-Out Resin (Ultradent Products) on the labial surfaces of the teeth to be whitened.	Figure 12. Tray material in UltraVac Vacuum Former (Ultradent Products) showing a 2-inch drop of the tray material when heated sufficiently.
Figure 13. Ultra-Trim Scalloping Scissors (Ultradent Products) scalloping the gingival margins to adapt precisely to the gingival margin.	Figure 14. Tray perfectly trimmed to the gingival margin, showing labial reservoir outline.

With the take-home systems, custom trays are fabricated to trap the agent against the tooth surface. A reservoir created by placing a die spacer over the teeth can be created, or alternatively no die spacer is used. The reservoir technique creates a small space on the inside surface of the tray immediately adjacent to the buccal surface of the tooth. This space will trap a greater quantity of bleach than a nonreservoir technique. The increased bleach quantity will release more oxygen ions over a longer period of time in the vicinity of the tooth, creating a greater early whitening effect.³⁶ Using colorimetric analysis, a study by Matis found that teeth lightened with trays containing a reservoir were lighter in color than teeth lightened with trays that did not have a reservoir. However, the difference was below the threshold of visual detection.³⁷ It is also of importance to note that the amount of active material left after a period of time varies with tray design. In a study looking at the total carbamide peroxide percent recovered after timed use in various tray designs, Matis, et al demonstrated that the use of reservoirs resulted in a recovery of significantly higher carbamide peroxide after 2 hours.³⁸ The use of reservoirs may or may not be necessary, with published data supporting both points of view³⁹ (Figures 11 to 14).
Sales of over-the-counter whitening products have been estimated to approach $1 billion a year in North America alone.13 Companies (eg, Procter & Gamble, Colgate) offer whitening products whose effects have been documented.^40,41 Crest Whitestrips (Procter & Gamble), containing a 6.5% hydrogen peroxide, were introduced in 2001. Many different versions of Colgate Platinum are available. Initially offered as whitening strips of various concentrations of hydrogen peroxide, a new delivery system utilizing a gel that is painted on the teeth (Colgate Simply-White Whitening Gel) containing 5.9% hydrogen peroxide has recently been introduced; it exceeds the ADA minimum requirements to claim clinical efficacy. ⁴²

TOOTH SENSITIVITY
Transient tooth sensitivity occurring after whitening teeth with the products described in this article is dose and time dependent. The higher the dose or concentration of the whitening agent and the longer the teeth are exposed, the greater the risk of tooth sensitivity.⁴³ If sensitivity occurs, the easiest way to address the problem is to decrease the time the patient treats the teeth or decrease the dosage of the peroxide or carbamide peroxide. Many products contain water to decrease the dehydration effects of whitening (Opalescence). Fluoride and potassium nitrate have been added to certain products such as Opalescence PF to decrease the incidence of tooth sensitivity. Potassium nitrate penetrates the dentinal tubules and depolarizes the nerves, decreasing the painful stimulus.⁴⁴ Potassium nitrate gels, which can be used in bleaching-type trays to reduce hypersensitivity of root surfaces, include UltraEZ (Ultra-dent Products), Den-Mat Desensitize (Den-Mat), and Relief (Discus Dental). A preloaded tray version of UltraEZ is also available. Recently, amorphous calcium phosphate was added to products like Zoom2 (Discus Dental) to treat hypersensitivity.

CONCLUSION

Dental clinicians are in a unique position to play an active role in encouraging and educating dental patients regarding the choices that are available for tooth whitening. Tooth whitening is the easiest and least expensive of the treatment options that are available to change the shade of the dentition.

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References

1. Burchard HH. A Textbook of Dental Pathology and Therapeutics. Philadelphia, Pa: Lea and Febiger; 1898.
2. Fitch CP. Etiology of the discoloration of teeth. Dental Cosmos. 1861;3:133-136.
3. Harlan AW. Hydrogen dioxide (in the treatment of alveolar abscess, pyorrhea and the bleaching of teeth). Dent Cosmos. 1882;24:515-523.
4. White JD. Bleaching. Dental Register of the West. 1861;15:576-577.
5. Wennstrom J, Lindhe J. Effect of hydrogen peroxide on developing plaque and gingivitis in man. J Clin Periodontol. 1979;6:115-130.
6. Volpe AR, Manhold JH, Manhold BS, et al. Gingival tissue oxygenation: the effect of a single application of four commercial preparations. J Periodontol. 1966;37:478-482.
7. Kelly TF. Hydrogen peroxide shows value of use. Dent Stud. 1976;54:66,82
8. Marshall MV, Cancro LP, Fischman SL. Hydrogen peroxide: a review of its use in dentistry. J Periodontol. 1995;66:786-796.
9. Asato R. Oxidation/reduction: bleaching agents. Kapií olani Community College Web site. Available at: http://library.kcc.hawaii.edu/external/chemistry/everyday_bleach.html. Accessed May 6, 2006.
10. Schneider HG, Birkholz C, Hampel W. Clinical experience with the peroxide-containing gingival strip from the Leipziger Arzneimttelwerk. Dtsch Stomatol. 1966;16:656-667.
11. Flaitz CM, Hicks MJ. Effects of carbamide peroxide whitening agents on enamel surfaces and caries-like lesion formation: an SEM and polarized light microscopic in vitro study. ASDC J Dent Child. 1996;63:249-256.
12. Goff S. Getting the white right. Dental Products Report. Jan 2005:14-19. Available at: http://www.dentalproducts.net/xml/display.asp?file=2716&bhcp=1. Accessed July 20, 2006.
13. Fasanaro TS. Bleaching teeth: history, chemicals, and methods used for common tooth discolorations. J Esthet Dent. 1992;4:71-78.
14. Haywood VB, Heymann HO. Night-guard vital bleaching. Quintessence Int. 1989;20:173-176.
15. Haywood VB, Heymann HO. Nightguard vital bleaching: how safe is it? Quintessence Int. 1991;22:515-523.
16. Yarborough DK. The safety and efficacy of tooth bleaching: a review of the literature 1988-1990. Compendium. 1991;12:191-196.
17. Pugh G Jr, Zaidel L, Lin N, et al. High levels of hydrogen peroxide in overnight tooth-whitening formulas: effects on enamel and pulp. J Esthet Restor Dent. 2005;17:40-47.
18. Haywood VB, Leonard RH, Dickinson GL. Efficacy of six months of nightguard vital bleaching of tetracycline-stained teeth. J Esthet Dent. 1997;9:13-19.
19. Cooper JS, Bokmeyer TJ, Bowles WH. Penetration of the pulp chamber by carbamide peroxide bleaching agents. J Endod. 1992;18(7):315-317.
20. Wade LG Jr. Conjugated systems. In: Organic Chemistry. 3rd ed. Upper Saddle River, NJ. Prentice Hall; 1994: chapter 15, 695, 1106.
21. Boksman L, Jordan RE. Conservative treatment of the stained dentition: vital bleaching. Aust Dent J. 1983;28:67-72.
22. Jordan RE, Suzuki M, Hunter JK, et al. Conservative treatment of the tetracycline stained dentition. Alpha Omegan. 1981;74:40-49.
23. Boksman L, Jordan RE, Skinner DH. A conservative bleaching treatment for the nonvital discolored tooth. Compend Contin Educ Dent. 1984;5:471-475.
24. Jordan RE, Boksman L. Conservative vital bleaching treatment of discolored dentition. Compend Contin Educ Dent. 1984;5:803-807.
25. CRA Newsletter. Issue 4, 2000.
26. CRA Newsletter. Issue 26, 2002.
27. Kugel G. Is there a benefit to light-activated tooth whitening? J Can Dent Assoc. 2005;71:420-421.
28. Drug-induced photosensitivity. Family Practice Notebook.com. Available at: http://www.fpnotebook.com/DER202.htm. Accessed May 6, 2006.
29. Matis BA, Gaiao U, Blackman D, et al. In vivo degradation of bleaching gel used in whitening teeth. J Am Dent Assoc. 1999;130:227-235.
30. Mokhlis GR, Matis BA, Cochran MA, et al. A clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime use. J Am Dent Assoc. 2000;131:1269-1277.
31. Araujo EM, Baratieri LN, Vieira LC, et al. In situ effect of 10% carbamide peroxide on microhardness of human enamel: function of time. J Esthet Restor Dent. 2003;15:166-173.
32. White DJ, Kozak KM, Zoladz JR, et al. Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties. Compend Contin Educ Dent. 2002;23:41-48.
33. Clark LM, Barghi N, Summitt JB, et al. Influence of fluoridated carbamide peroxide bleaching gel on enamel demineralization. Abstract 0497. International Association for Dental Research Web site. Available at: http://iadr.confex.com/iadr/2006Orld/techprogram/abstract_76079.html. Accessed May 2006.
34. Al-Qunaian T. The effect of whitening agents on caries susceptibility of human enamel. Oper Dent. 2005;30:265-270.
35. Basting RT, Rodrigues AL Jr, Serra MC. The effects of seven carbamide peroxide bleaching agents on enamel microhardness over time. J Am Dent Assoc. 2003;134:1335-1342.
36. Buyersí guide to whitening systems. Dent Today. Dec 2004;23(12):120.
37. Matis BA, Hamdan YS, Cochran MA, et al. A clinical evaluation of a bleaching agent used with and without reservoirs. Oper Dent. 2002;27:5-11.
38. Matis BA, Yousef M, Cochran MA, et al. Degradation of bleaching gels in vivo as a function of tray design and carbamide peroxide concentration. Oper Dent. 2002;27:12-18.
39. Javaheri DS, Janis JN. The efficacy of reservoirs in bleaching trays. Oper Dent. 2000;25:149-151.
40. Gerlach RW, Zhou X. Clinical trial comparing two daytime hydrogen-peroxide professional vital-bleaching systems. Compend Contin Educ Dent. 2004;25(8 suppl 2):33-40.
41. Sagel PA, Landrigan WF. A new approach to strip-based tooth whitening: 14% hydrogen peroxide delivered via controlled low dose. Compend Contin Educ Dent. 2004;25(8 suppl 2):9-13.
42. Gambarini G, Testarelli L, De Luca M, et al. Efficacy and safety assessment of a new liquid tooth whitening gel containing 5.9% hydrogen peroxide. Am J Dent. 2004;17:75-79.
43. Boksman L. A large proportion of the patients who undergo teeth whitening procedures in my office experience sensitivity. How can I minimize this side effect? J Can Dent Assoc. Dec 2005/Jan 2006;71:829-830.
44. Orchardson R, Gillam DG. The efficacy of potassium salts as agents for treating dentin hypersensitivity. J Orofac Pain. 2000;14:9-19.

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Dr. Boksman is adjunct clinical professor at the Schulich School of Medicine and Dentistry, University of Western Ontario. He is a fellow in the Academy of Dentistry International and in the International College of Dentists. He can be reached at (519) 641-3066, extension 292, or lboksman@clinicianschoice.com.

Disclosure: Dr. Boksman holds a paid part-time consulting position with Clinicians Choice and Clinical Research Dental, with the title of director of clinical affairs.

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Continuing Education Test No. 81.1

After reading this article, the individual will learn:

ï about the development of bleaching agents, and
ï how to choose the appropriate tooth-whitening system for each patient.

1. Hydrogen peroxide in dentistry ____.
a. has been in use for more than 100 years
b. has been found to promote bone healing
c. has no antimicrobial effects
d. cannot be used in conjunction with periodontal surgery

2. The carbamide peroxide reaction is defined as follows:
a. Carbamide peroxide degrades into hydrogen peroxide and water.
b. Carbamide peroxide degrades into oxygen and water.
c. Carbamide peroxide degrades into ammonia and carbon dioxide.
d. Carbamide peroxide degrades into hydrogen peroxide and urea.

3. Hydrogen peroxide in all whitening agents _____.
a. is toxic to soft tissues
b. is safe to use
c. is detrimental to the pulp
d. decreases the microhardness of enamel

4. Which of the following is not an intrinsic stain?
a. nicotine staining
b. fluorosis
c. amalgam staining
d. tetracycline

5. In-office tooth whitening is best for ___.
a. patients with time limitations
b. patients who need close monitoring
c. teeth that have been endodontically treated
d. all of the above

6. For in-office tooth whitening, _____.
a. heat increases the whitening effect
b. light increases the whitening effect
c. concentration is the only critical factor that determines the degree of whitening
d. contact time and concentration of active ingredients are the critical factors

7. Hydrogen peroxide _____.
a. increases enamel’s susceptibility to develop caries
b. decreases the microhardness of enamel
c. in Opalescence PF decreases susceptibility for caries
d. with fluoride added is not absorbed into enamel

8. Tooth sensitivity during whitening ____.
a. can be treated by decreasing dosage and time of whitening
b. can be treated with potassium nitrate to depolarize nerves
c. can be reduced by using agents that contain water
d. all of the above

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To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 81.1), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).

]]> https://www.dentistrytoday.com/sp-329126174/ Tue, 01 Aug 2006 00:00:00 +0000 https://www.dentistrytoday.com/?p=10591 Oral complications of cancer chemotherapy have been recognized for many years. Candidiasis, mucositis, chemo-therapy-induced mucosal ulcerations, and altered salivary function are all well-documented side effects of chemotherapeutic agents.¹ In 1983, osteonecrosis associated with head and neck cancer patients who had received radiation to the jaws was first described.² The pathological changes seen in osteoradionecrosis are believed to be due to a decrease in vascularity resulting in tissue hypoxia secondary to radiation injury of the blood vessels. Osteoradionecrosis of the mandible occurs with a much greater frequency than in the maxilla, most likely due to the solitary mandibular blood supply provided by the inferior alveolar artery. It is well-known that the presence of active carious lesions and/or periodontal disease, as well as post-radiation dental extractions and surgical manipulation, increase the risk for development of osteoradionecrosis.³
A new disease entity occurring in patients who were receiving bisphosphonate therapy was described in late 2003 by Marx (Figure 1). In a letter to the editor of the Journal of Oral and Maxillofacial Surgery, it was noted that 36 patients receiving intravenous (IV) bisphos-phonate (BP) treatment were seen with avascular necrosis of the jaws. Twenty-four patients were on pamidronate (90 mg monthly), and 12 patients were receiving zoledronate (4 mg monthly). Eighteen patients of the 36 patients were on BPs for multiple myeloma, 17 patients were being treated for metastatic breast cancer, and 1 patient was receiving treatment for osteoporosis (OP). All patients presented with necrotic bone in the mandible (80%), maxilla (14%), or both (6%). These lesions were characterized as bisphosphonate-associated osteonecrosis of the jaw (ONJ). In 78% of cases, ONJ was associated with extraction of teeth or surgical manipulation. The remainder of cases appeared spontaneously without any known dental or oral trauma.⁴
The purpose of this paper is to review the mechanism of action of bisphosphonates, current uses of these drugs, and what is known regarding the pathology of ONJ. The current ONJ literature will be summarized, and recommendations for clinical care based on the analysis of reported cases will be presented.  

BISPHOSPHONATE MECHANISM OF ACTION

Figure 1. A patient with bisphosphonate-associated osteonecrosis of the mandible.

Figure 2. The cholesterol biosynthetic pathway. Inhibition of farnesyl diphosphate synthetase (FPP) by nitrogen-containing bisphosphonates.

Although BPs were known to be effective inhibitors of osteoclasts, until recently the exact mechanism of action was unclear. New research has elucidated the molecular mechanism of this class of drugs.⁵ The BP chemical structure is very similar to inorganic phosphate, a regulator of bone metabolism. BPs have a high affinity for divalent ions, particularly calcium, resulting in the in vivo targeting of hydroxyapatite bone mineral surfaces.⁶ The acidic environment created by the osteoclast within the resorption lacunae can release BPs from the bone surface, where they are internalized through endocytosis.^7,8 The first-generation BPs etidronate, tiludronate, and clodronateóare metabolized within the cell to form toxic analogs of ATP, which lead to the initiation of osteoclast apoptosis.^9,10 The second and third generation of nitrogen-containing BPs, including pamidronate and zoledronate, act through inhibition of the cholesterol biosynthetic pathway (Figure 2). Several studies have recently shown that farnesyl diphosphate synthetase is inhibited by all nitrogen-containing BPs. This enzyme is critical for the production of cholesterol, isoprenoid lipids, farnesyl diphosphate (FPP), and geranylgeranyl diphosphate (GGPP). These isoprenoid lipids are critical for osteoclast functions including but not limited to cell adhesion, formation of a ruffled border, and apoptosis.^11,12

PATHOPHYSIOLOGY OF OSTEONECROSIS

Osteonecrosis can affect all skeletal bones,  but it is most common in the hip and the mandible.^13-19 The pathophysiology of osteo-necrosis appears to be an interruption or compromise of the blood supply as a result of trauma or nontraumatic systemic conditions, including corticosteroid administration, coagulopathies, and alcoholism. While many conditions are associated with osteonecrosis, one of the most significant appears to be hypofibrinolysis.^20-23 Glueck and colleagues studied 55 patients with alveolar osteonecrosis and evaluated thrombophilia (increased tendency to form intravascular thrombi), anticardiolipin antibodies (associated with thrombophilia), and hypofibrinolysis (decreased ability to lyse thrombi). Thrombophilia was assessed by activated protein C resistance, while fibrinolysis was quantitated by plasminogen activator inhibitor activity (the major inhibitor of fibrinolysis) and stimulated tissue plasminogen activator (the major stimulator of fibrinolysis). Their data indicated that in 43 of 55 patients (78%), one or more of the tests was positive for thrombophilia or hypofibrinolysis.²⁰ At the present time it is unclear if cancer patients with maxillofacial osteonecrosis have fibrinolytic abnormalities; however, these studies suggest that evaluation of coagulation abnormalities in BP-associated osteonecrosis patients is an important parameter that needs evaluation.

USES OF BISPHOSPHONATES

Bisphosphonates and Hypercalcemia of Malignancy

BPs (inhibitors of osteoclast action) are used in the treatment of postmenopausal and steroid-induced osteoporosis, Paget’s disease of bone, multiple myeloma, hypercalcemia of malignancy, and tumor-associated osteolysis in breast, prostate, lung, and other soft-tissue cancers.^24-27 Hypercalcemia of malignancy is a serious complication of cancer that affects 10 to 20% of all cancer patients at some point during the course of their disease.^28-30 It can occur in the presence or absence of bone metastases. In patients without skeletal involvement, it occurs most often in squamous cell carcinoma of the lung, head and neck tumors, and in renal cell carcinoma.³¹ In individuals with bone metastases, hypercalcemia of malignancy occurs in 30 to  80% of multiple myeloma patients, 30 to 65% of pa-tients with metastatic breast cancer, and less than 15% of patients with lung cancer. It occurs when the tumor cells release cytokines and para-thyroid hormone-related proteins as well as other bone-resorbing factors. This resorption of the bone causes an accelerated release of calcium into the circulation, which leads to hypercalcemia, a potentially life-threatening event. Management of this condition includes anti-cancer treatment and IV BPs.³¹

Bisphosphonates and Breast Cancer

Breast cancer accounts for approximately 30% of all new cancer cases in women. Fifty percent of breast cancer patients develop bone metastases, of which 40 to 70% have complications such as bone pain, pathological fracture, or spinal cord compression.^32,33 BPs are currently approved for the treatment and prevention of these skeletal-related events in breast cancer patients with bone metastases. At present, bisphosphonates are approved only for use in patients with bone metastases. However, studies to evaluate their efficacy in the prevention of bone metastases are ongoing.

Bisphosphonates and Multiple Myeloma

Multiple myeloma is the third most common hematologic malignancy in the United States. Myeloma tumor cells have been shown to secrete numerous bone-resorbing cytokines resulting in bone destruction, pathological fractures, hypercalcemia, and pain in a large majority of these patients. Several large placebo-controlled, randomized studies have shown a significant reduction in skeletal-related events (including pathologic fractures, spinal cord compression, radiotherapy or surgery to bone, and hypercalcemia) in multiple myeloma patients treated with bisphosphonates. Additionally, patients on BPs had significantly less myeloma-related bone pain than the placebo group.^34,35 New in vitro data show an antiproliferative and apoptotic effect of BPs on multiple myeloma cell lines.³⁶          

Case Reports of ONJ

Marx updated his initial report by studying a total of 119 patients with ONJ. Seventy-six of these patients presented to the University of Miami (presumably an additional 40 patients since his original report), and 43 cases were documented by his colleagues at other university centers. Fifty-two percent of patients were under treatment for multiple myeloma, 42% for breast cancer, 3.4% for prostate cancer, and 2.5% for OP. The location of the lesions and comorbidities were similar to the original report.³⁷ An additional 5 cases of suspected BP-associated osteonecrosis of the mandible were reported by Migliorati.³⁸ Three cases developed spontaneously and 2 cases were seen following tooth extraction. No information regarding patient diagnosis or length of BP therapy was presented. Prior to the original report by Marx, Wang et al³⁹ described 3 women receiving chemotherapy for metastatic breast cancer. Two patients developed necrotic bone subsequent to dental manipulation, and 1 patient spontaneously developed necrosis in the maxilla. Histological evaluation revealed necrotic bone without evidence of metastases. Wang, et al postulated that the osteonecrosis was due to the cancer chemotherapy. In a later communication, following their review of other reported cases of BP-associated osteonecrosis, the authors revealed that all 3 patients had been treated with BPs.⁴⁰
Lugassy, et al⁴¹ described 3 patients with multiple myeloma on chronic BP therapy. The first patient had received BPs for 5 years and developed osteonecrosis of the left retromolar area. The osteonecrotic lesion responded to hyperbaric oxygen treatment. The second patient had several occurrences of infected, exposed bone that was ultimately eradicated after sequestrectomy and antibiotic treatment. Histopathologic examination of the surgical specimen revealed infection with Actinomyces. The third patient had developed exposed, infected bone following a mandibular extraction. This patient had been on IV BPs for a 5-year period. Again, histopathology revealed extensive Actinomyces colonization. This patient was successfully treated with large doses of IV penicillin.
Ruggiero et al⁴² reported on 63 cases from 2 medical centers over a 26-month period. Twenty-eight patients had multiple myeloma, 20 patients were diagnosed with breast cancer, 3 patients had lung cancer, 3 patients had prostate cancer, 1 patient had plasmacytoma, and 1 patient   had leukemia. Seven patients were diagnosed with OP and had not received chemotherapy. Thirty-nine patients presented with osteonecrosis of the mandible, and 23 had maxillary involvement. One patient had necrotic lesions in both jaws. Fifty-four of 63 patients had a recent extraction at the necrotic site. The remaining 9 patients had spontaneous bone exposure. Bacterial culture results were reported as normal oral flora. The authors reported that the duration of BP therapy ranged from 6 to 48 months; the treatment time for each individual patient was not noted. Treatment of necrotic lesions ranged from conservative management to resection, with the majority of patients undergoing sequestrectomy. There was no information in this report about oral hygiene in these subjects.
Additional ONJ case series have appeared in the literature since the publication of the initial description of bisphosphonate-associated ONJ.^43-45 Migliorati, et al identified 18 patients (17 with bone metastases, one patient with OP) who had ONJ. Ten of the affected patients were under treatment for breast cancer, 3 patients had multiple myeloma, one patient had prostate cancer, one patient had prostate carcinoma/lymphoma, one patient had ovarian cancer, and one patient had ovarian/breast carcinoma. With the exception of the patient with OP who was being treated with oral alendronate, all patients were receiving IV pamidronate or zoledronate with a mean treatment time of 25 months (range of 4 to 41 months). Two patients developed ONJ spontaneously, and the remaining patients developed the disease secondary to dental extractions, infection, or trauma.43 In a report from Belgium, Maerevoet, et al44 reported 9 cases of ONJ in patients receiving zoledronate for skeletal protection. Five patients had breast cancer, and 4 patients had multiple myeloma. Unique to this case series was that all cases of ONJ were spontaneous in that none of the patients had undergone prior dental treatment. The authors reported that at their institution the incidence of ONJ in patients treated with zoledronate was 4.6%.
Durie, et al⁴⁵ conducted a Web-based survey to evaluate risk factors for ONJ. A total of 1,203 patients (904 with multiple myeloma and 299 with breast cancer) responded to the survey. While this report did not confirm the presence of ONJ, the authors determined that 62 patients with myeloma had ONJ and 54 patients had suspicious findings. In the breast cancer patients, 13 patients were believed to have ONJ and 23 patients had suspicious lesions. Neither corticosteroids nor thalidomide was associated with the development of ONJ; however, 81% of ONJ patients had a history of underlying dental problems. This study reported an ONJ incidence of 10% among patients receiving zoledronate.   

Table 1. Oral Bisphosphonate ONJ Cases. Author No. of Cases Journal Methodology Ruggiero, et al 7 JOMS, 2004 Case Report Migliorati, et al 1 Cancer, 2005 Case Report Marx, et al 3 JOMS, 2005 Case Report Carter, et al 1 Med J Aus, 2005 Case Report Purcell and Boyd 1 Med J Aus, 2005 Case Report

A retrospective chart review of 4,000 patients that received IV BPs at MD Anderson Cancer Center (sponsored by Novartis Pharma-ceuticals, the manufacturer of Aredia [pamidronate disodium] and Zometa [zoledronic acid]) identified 33 cases of ONJ (0.83% overall incidence). Fourteen patients had breast cancer (incidence of 1.2%), and 15 patients were undergoing treatment for multiple myeloma (incidence of 2.8%).⁴⁶ Similar to the Durie study, none of the cases of ONJ reported were clinically confirmed. Based on the extremely limited data detailed above, the incidence of ONJ in patients receiving IV BPs ranges from 0.83 to 10%. Of note are several recent reports of ONJ in OP patients treated with oral BPs, suggesting that ONJ may be associated with BPs other than zoledronic acid and pamidronate.^4,37,42 The incidence of ONJ associated with oral bisphosphonates, however, appears to be extremely low. A recent review of the literature revealed only 13 cases of documented ONJ associated with the use of oral bisphosphonates (Table 1).

LIMITATIONS OF THE CURRENT KNOWLEDGE

While these limited numbers of case reports seem to establish an association between BPs and ONJ, numerous questions regarding the incidence, etiology, pathogenesis, and natural history of this condition need to be addressed. The need for prospective clinical studies to ascertain the risk factors associated with the development of ONJ is obvious. One of the primary factors limiting research on ONJ is the lack of a consistent definition of ONJ, which is necessary before the incidence and prevalence of the disease can be accurately determined. A uniform definition of ONJ is needed to clarify lesions that are “slow healers” (particularly in patients taking multiple anticancer medications) after dental procedures versus true cases of ONJ.

PREVENTION AND MANAGEMENT OF ONJ

Recently, two papers have been published with guidelines related to the prevention and management of ONJ.^47,48 One of the papers contains guidelines from the American Academy of Oral Medicine, and the other paper is authored by a group of dentists and oncologists. Both papers present similar approaches to the management of ONJ. It should be noted that the management strategies presented in these papers are not based on clinical studies, but rather on strategies used for patients with osteoradionecrosis.
Guidelines have been developed for 3 distinct groups: 1) patients who will be initiating treatment with BPs; 2) patients who are currently taking BPs; and 3) patients who have developed ONJ.

PREVENTIVE MEASURES PRIOR TO STARTING BISPHOSPHONATE THERAPY

Teeth with a poor prognosis should be extracted, and any other dental surgical procedures should be completed prior to the initiation of BP treatment.
Prior to initiating BP therapy, patients should receive a thorough oral/dental examination, including radiographic evaluation.
The need for good oral hygiene should be stressed.

PREVENTIVE MEASURES FOR PATIENTS CURRENTLY TAKING BISPHOSPHONATES

• While taking BPs, it is recommended that patients should have dental recall visits every 3 to 6 months.
• Routine dental cleaning should be performed with care taken to prevent soft-tissue injury.
• Removable dentures should be checked for their potential to induce trauma.
• Endodontic therapy is preferred over tooth extraction.
• Elective therapy such as implant treatment should be avoided in patients on IV bisphosphonates.
• If surgery is necessary, antibiotics should be considered both presurgically and postsurgically. It has been suggested that antibiotics be given prior to invasive dental procedures and continued for at least 10 days after a dental procedure. Amoxicillin has been recommended as a good first choice, with azithromycin or quinolones as second choices.
• Primary closure of all oral wounds including extraction sites should be attempted.
• Treatment of patients with osteonecrosis of the jaw
• Because of impaired wound healing in patients with ONJ, a nonsurgical approach to the management of these lesions is recommended.
• Only minimal bony debridement of the ONJ lesion should be performed to remove sharp edges.
• Removable appliances should be constructed to protect the ONJ lesion from further trauma.
• Chlorhexidine mouth-rinses (0.12%) are recommended.

 

The use of antibiotics to treat ONJ lesions has had equivocal results. Antibiotic use should be based on clinical judgment, although choice of an antibiotic should be determined by culture and sensitivity testing of the lesion, if possible. It has been suggested that a combination of amoxicillin and metronidazole may be helpful.^47,48

Table 2. Hyperbaric Therapy for ONJ at the Duke Center for Hyperbaric Medicine and Environmental Physiology (CHMEP). HBO Therapy (2.0 atm, 2 hr) Responses Courses Patients Dives Stable Resolved 1 10 36 – 40 4 6 2 1 60 – 1 3 1 120 – 1

During examination and culture of ONJ lesions, the possibility of fungal infection should be considered. In lesions where cultures have demonstrated the presence of a fungal infection, patients should be placed on nystatin oral rinses or mycostatin troches.
Hyperbaric oxygen (HBO) therapy has been employed to prevent and treat osteoradionecrosis in the maxillofacial bones. The data regarding the use of HBO therapy in ONJ patients has been controversial. Initial reports indicated that HBO was not effective in the treatment of ONJ. However, the treatment protocols as well as the criteria for success were not reported, or HBO protocols for the treatment of osteoradionecrosis (20 dives at 2.0 atm) were used. A recent study, however, from investigators at Duke University Medical Center demonstrated that HBO may be effective in resolving ONJ lesions (Table 2). In that report, they used an intensive treatment protocol that consisted of between 40 and 120 dives and achieved complete resolution of ONJ in 67% of cases.49 This preliminary study suggests that further research is needed to determine optimal therapy for patients with ONJ and underscores the need for a prospective clinical trial to evaluate the efficacy of HBO in the treatment of BP-associated ONJ.

SHOULD BISPHOSPHONATE THERAPY BE STOPPED IN PATIENTS WHO DEVELOP ONJ?

There is no clear evidence that suggests that stopping BP therapy has any effect on the healing of an ONJ lesion. Since BPs have an extremely long half-life in the bone, it would seem that stopping BP therapy would not have a dramatic effect. The decision to stop BPs should be made by the patient’s physician and is based on the risk/benefit ratio determined for each case.

SUMMARY

ONJ appears to be associated with BPs; however, the pathophysiology, incidence, and co-morbidities require further investigation. The major risk factors identified to date appear to be cancer (or chemotherapy for cancer) and dental procedures or oral trauma. A clear definition of ONJ is critical to understanding this disease entity. Although recommendations regarding the prevention and management of ONJ exist, clinical studies are needed to establish more definitive guidelines for the management of ONJ. The use of intensive hyperbaric oxygen therapy may be beneficial to patients with ONJ.

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Dr. Landesberg is associate professor in the Division of Oral and Maxillofacial Surgery in the Columbia University College of Dental Medicine and interim director of the Oral and Maxillofacial Surgery outpatient clinic. She received her DMD from the University of Connecticut, School of Dental Medicine, and her residency training in oral and maxillofacial surgery at Strong Memorial Hospital/University of Rochester. Dr. Landesberg has a PhD in microbiology/immunology from the University of Rochester and completed a post-doctoral research fellowship in the Department of Orthopedics at the University of Rochester. She maintains a private practice and is an attending surgeon in oral and maxillofacial surgery at the Columbia University Medical Center/ New York Presbyterian Hospital. Her areas of research include the elucidation of the molecular basis of temporomandibular joint dysfunction/arthritis, the mechanisms involved in the pathogensis of osteonecrosis of the bone, and engineering new delivery systems for the regeneration of craniofacial bone. She can be reached  at (212) 305-7626 or RL351@columbia.edu.

Dr. Wilson is chief resident in oral and maxillofacial surgery at Columbia University College of Dental Medicine and the Columbia University Medical Center/New York Presbyterian Hospital. He received his DDS from Columbia University College of Dental Medicine and his MD from Columbia College of Physicians and Surgeons. He can be reached at (212) 305-7626 or tbw4@columbia.edu.

Dr. Grbic is professor and director of the Division of Oral Biology and the Center for Clinical Research in Dentistry at the Columbia University College of Dental Medicine. He received his DMD from the Fairleigh Dickinson School of Dentistry and his certificate in periodontology and a MMSc in oral biology from the Harvard School of Dental Medicine. His research interests include the diagnosis and pharmacotherapeutic management of periodontal diseases, the relationship between periodontal disease and systemic diseases, and the design and conduct of clinical trials. Dr. Grbic maintains a private practice in periodontics in New York City. He can be reached at (212) 305-4640 or jtg2@columbia.edu.

Disclosure: Drs. Landesberg and Grbic are consultants for the Novartis Pharmaceuticals Corporation.

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References

]]> https://www.dentistrytoday.com/sp-744712584/ Tue, 01 Aug 2006 00:00:00 +0000 https://www.dentistrytoday.com/?p=10968 Dental patients taking anticoagulant medication pose a challenge for the clinician. Dentists are often required to manage bleeding as part of routine oral surgery or dental procedures, and altered hemostasis can lead to complications. Nevertheless, use of these medications is generally important for the patientís health, and any alterations in the anticoagulant regimen may have untoward sequelae. In addition, several medications can affect the clotting mechanism, potentially compromising hemostasis. This article will review a variety of anticoagulant medications and the medical conditions that necessitate their use. In addition, recommendations for altering anticoagulant medication prior to performing routine oral surgery will be reviewed.

Figure 1. A patient with vascular fragility due to long-term corticosteroid use presented with this localized bruise as a result of irritation from an ill-fitting partial denture.

Hemostasis depends on several critical factors.¹ An adequate number of platelets and proper platelet function are essential. The integrity of the vasculature also plays an important role in hemostasis. Vascular integrity can be compromised by vitamin C deficiency, viral and bacterial infections, or as a result of the aging process or through various disease states (Figure 1). Adequate levels of clotting factors and proper functioning of the fibrinolytic pathway are also essential. Finally, many pharmaceuticals can compromise hemostasis, which is the focus of this article. Chemically induced anticoagulation as a therapeutic strategy is required treatment for a variety of diseases. Anticoagulation is also an undesirable side effect of some drugs.¹
Many drugs can interfere with hemostasis. In addition to anticoagulant medications, these agents include antibiotics, aspirin, and anti-inflammatory medications. Drugs used in the treatment of cancer can interfere with the clotting mechanism, as does excessive alcohol intake. The dentist should be aware of any herbal supplements the patient is taking, as a number of these can also affect hemostasis.¹

LABORATORY TESTS

The coagulation cascade involves the intrinsic, extrinsic, and common pathways, which have been found to be highly interconnected. The intrinsic pathway requires the clotting factors VII, IX, X, XI, and XII. The extrinsic pathway is initiated with the release of tissue factor II. The common point in both pathways is the activation of factor X to factor Xa. Factor Xa activates prothrombin (factor II) to thrombin (factor IIa). Thrombin, in turn, converts fibrinogen to fibrin.
Dentists should be able to order and interpret appropriate laboratory tests when minor oral surgery is required for anticoagulated patients. The most frequently used tests are the Prothrombin Time (PT) and International Normalized Ratio (INR).
The PT measures the effectiveness of the extrinsic and common pathways. The normal value is approximately 10 to 15 seconds. Because of the variability in PT reported by different laboratories, it is no longer considered adequate to use PT to monitor the level of anticoagulation. In order to reduce variability, INR was developed as a consistent test for measuring anticoagulation status. INR is the more reliable and consistent measure. A normal individual should have an INR of 1.0.²
Dependent upon the medical condition, physicians will prescribe anticoagulant medication so that patients demonstrate an INR in a therapeutic range of approximately 2.0 to 3.5. These conditions include states in which thromboembolism could cause serious morbidity or death, such as post myocardial infarction, and prevention of deep venous thrombosis (DVT). Additionally, patients with atrial fibrillation are anticoagulated because of the greater likelihood of blood clot formation due to turbulent blood flow through the heart. In those individuals with prosthetic heart valves and certain hypercoagulable states, the INR should be approximately 3.5. If the dentist encounters a patient with an INR greater than 4.0, the patient should be referred to the physician for evaluation. An INR greater than 4.0 is usually considered nontherapeutic, and the patient is at risk for serious bleeding complications.³
Another important test used to assess coagulation is the activated Partial Thromboplastin Time (aPTT), which measures the intrinsic and common pathways. A normal test time is 25 to 40 seconds. The aPTT is commonly used to measure the effectiveness of the anticoagulant heparin. This medication is typically administered intravenously on an inpatient basis.1 Heparin therapy will be discussed in more detail later in this article.
A clinical laboratory test that may be used to monitor platelet function is Bleeding Time. Bleeding Time is measured by making a small incision on the forearm while a blood pressure cuff, inflated to 40 mm Hg, is placed on the upper arm. The time for the bleeding to stop is measured. Normal Bleeding Time is in the range of 2 to 8 minutes. This test can be quite variable and is generally used as a screening tool or in combination with other tests.¹
As opposed to the Bleeding Time, a platelet count is more likely to be available in the patient’s medical record. Normal platelet counts are in the range of 100,000 to 400,000/mm3. If the count falls below 100,000/mm³, then the patient is considered to have thrombocytopenia. Thrombocytopenia represents a potential for compromised hemostasis. When the platelet count falls below 50,000/mm³, the risk of prolonged bleeding is especially significant. Spontaneous hemorrhage may occur when the platelet count falls below 25,000/mm3. Thrombocytopenia is frequently associated with a serious medical condition. It can be drug-induced, caused by bone marrow failure, hypersplenism, or cancer chemotherapy, or be of idiopathic origin.¹

Table 1. Herbal Supplements That Affect Platelet Aggregation: Agents and Uses.

Garlic – lowers cholesterol and blood pressure Gingko – improves memory function Ginseng – enhances endurance, lowers blood sugar Ginger – antinausea, antispasmodic Feverfew – migraine headaches, arthritis Vitamin E – antioxidant, cancer prevention

A situation more commonly encountered in the dental office is thrombocytopathy. This condition represents a state of compromised platelet function and aggregation. Thrombocytopathy can be associated with aspirin, nonsteroidal anti-in-flammatory drugs (NSAIDs), and drugs used to decrease the risk for stroke or heart attack, such as Aggrenox (aspirin/extended-release dipyridamole; Boehringer Ingelheim Pharmaceuticals) and Plavix (clopidogrel bisulfate; Bristol-Myers Squibb/ Sanofi Pharmaceuticals Partnership). Certain herbal supplements can be associated with compromised platelet aggregation (Table 1). It is recommended that patients who are scheduled for oral surgery refrain from taking any herbal substances for 1 week prior to the surgery.^4,5

ANTICOAGULANT MEDICATIONS

Patients seen in the dental office may have been instructed by their physician to take  one low-dose aspirin daily to prevent thromboembolic events associated with stroke or myocardial infarction. One low-dose aspirin contains 81 mg, whereas one regular-strength aspirin contains 325 mg. Some health professionals recommend taking 325 mg every other day. Cessation of low-dose aspirin therapy prior to oral surgery has been controversial. Dentists have been concerned with potential bleeding complications; however, patients who are receiving aspirin therapy are at risk for emboli and myocardial infarction if the medication is stopped.⁶ Studies have shown that patients undergoing minor oral surgery, including implant surgery and third molar extraction, experienced minimal bleeding complications when on low-dose aspirin therapy. These complications were controlled with local measures. The results indicated that low-dose aspirin therapy may be continued even if a patient requires minor oral surgery.^7,8
Medications such as Plavix or Aggrenox are prescribed to prevent stroke and heart attack. Plavix irreversibly binds to the platelets, and Aggrenox combines 25 mg of aspirin and 200 mg of extended-release dipyridamole, providing additive antiplatelet actions. Dipyrid-amole reversibly inhibits adenosine uptake leading to increased cyclic AMP, and inhibits cyclic GMP phosphodiesterase resulting in an increase of cyclic GMP. Both products are platelet antiaggregants. These medications may also be continued during minor oral surgical procedures. Local measures should be sufficient to control bleeding.⁹ If any significant bleeding is anticipated, dentists should consult with the patientís physician to determine if alterations to the anticoagulant regimen should be considered.
Another class of drug that disrupts platelet activity is the NSAIDs. These medications reversibly bind to the platelet for a limited period of time (approximately 6 hours). Used by themselves, there should be no complications if a patient is taking a NSAID. Complications can arise if the patient is taking anticoagulant medication and a NSAID. This combination could increase the risk for bleeding.¹⁰

Table 2. Target INR for Specific Medical Conditions.

CONDITION INR Venous thrombosis 2.0 – 3.0 Atrial fibrillation 2.0 – 3.0 Post myocardial infarction 2.5 – 3.5 Presence of a mechanical heart valve 3.0 – 3.5 Hypercoagulable states 3.0 – 4.0

The medication of greatest concern relative to bleeding complications, and that is a source of confusion for many practicing dentists, is the anticoagulant warfarin sodium, which is often referred to by the brand name Coumadin (Bristol-Myers Squibb Company).¹¹  Coumadin is used to prevent thromboembolic events that can occur in a variety of conditions. These include ischemic heart disease, deep venous thrombosis and pulmonary embolism, the presence of artificial heart valves, and hypercoagulable disease states. Genetic or acquired diseases include antiphospholipid anti-bodies (Lupus Anticoagulant), deficiencies of antithrombin, protein C and its co-factor protein S, and Factor V Leiden. It should be noted that most patients with Lupus Antico-agulant do not have lupus erythematosus or other systemic autoimmune disorders. Factor V Leiden is an autosomal dominant condition in which Factor V remains active, which facilitates overproduction of thrombin, leading to excess fibrin generation and excess clotting. It is named after the city of Leiden (Netherlands), where it was first identified in 1994. The effect of Coumadin is measured by the INR or PT.¹ Typical INR values for specific medical conditions requiring Coumadin are listed in Table 2.
Coumadin has a mean half-life of 40 hours, which can vary among individuals from 20 to 60 hours (Physician’s Desk Reference). Coumadin interferes with the synthesis of vitamin K. Vitamin K is a necessary co-factor in chemical reactions at numerous points in the coagulation cascade. Numerous drug interactions are possible with this medication. The mechanism may be pharmacokinetic, in that the absorption, protein binding, or hepatic metabolism of warfarin is affected. In addition, drugs that affect vitamin K production can also alter hemostasis. Of particular importance to dentists are broad-spectrum antibiotics. These drugs can cause changes in the intestinal flora that might decrease vitamin K absorption.^12,13  One should be aware that multiple tooth extractions may make eating difficult and enhance the antibiotic-induced decrease in vitamin K availability. If it is necessary to prescribe a course of antibiotics, then the dentist may wish to consider having the patientís INR monitored. There are case reports demonstrating this interaction with single-dose amoxicillin prophylaxis recommended by the American Heart Association. There is no evidence to suggest that single-dose clindamycin interacts with warfarin.¹⁴

Figures 2a and 2b. Altering the dosage of anticoagulant medication would not be necessary when replacing this defective amalgam restoration.

Until recently, many dentists and physicians were of the belief that Coumadin should be discontinued in low-risk to moderate-risk patients undergoing dental procedures associated with bleeding. Some dentists even requested that the patient stop taking Coumadin for restorative or nonsurgical periodontal procedures (Figures 2a and 2b). However, there are documented cases of embolic complications in patients whose Coumadin therapy was discontinued for dental treatment.^15,16 In addition, there is evidence that thrombosis may also occur because of a temporary state of rebound hypercoagulability following cessation of anticoagulation therapy.¹⁷
Traditionally, when a patient at high risk for thrombus formation required oral surgey, hospitalization was required. High-risk patients include individuals with mechanical heart valves, those undergoing active treatment for DVT, or those with hypercoagulable disease states.¹⁸ These patients had their Coumadin discontinued and were placed on intravenous heparin. Although this remains the case for major oral surgery procedures, this approach was also used for relatively minor surgical procedures. Heparin is a mixture of glycosaminoglycans of different molecular weights. Heparin potentiates the action of antithrombin III and thereby inactivates thrombin (factor IIa) as well as factors IX, X, XI, XII, and plasmin, and prevents the conversion of fibrinogen to fibrin. This unfractionated heparin was generally administered intravenously in the hospital. It has a short half- life of about 50 to 90 minutes. When a surgical procedure was planned, the heparin was discontinued 4 to 6 hours prior to the procedure and restarted 4 to 6 hours later.^19,20 As a result, the period of time a patient was not anticoagulated was only a few hours. As the Coumadin the patient had been taking was metabolized and eliminated from the body, heparin remained as the anticoagulant. Two or three days after dental surgery was performed, the patient was restarted on Coumadin. The Coumadin was allowed to reach therapeutic levels, and the heparin was discontinued. This process required approximately 5 days of hospitalization and close patient monitoring.
In the past several years, low molecular weight heparins (LMWHs) have been introduced. This relatively new class of agents is ob-tained from chemical or enzymatic depolymerization of unfractionated heparin. Low molecular weight heparins have been used to prevent deep venous thrombosis and pulmonary emboli. In addition, they are used in the treatment of unstable angina and non-Q wave myocardial infarcts, and for embolism prophylaxis following major orthopedic and abdominal surgery.^19,20  Low molecular weight heparins have more recently been used as bridging therapy in order to discontinue Coumadin in preparation for dental procedures. Low molecular weight heparins are not approved as a substitute for Coumadin in patients with prosthetic heart valves.^20,21 Patients can self-administer these drugs subcutaneously on an outpatient basis. As an alternative to the previous technique involving unfractionated heparin, low molecular weight heparins have provided successful anticoagulation, require less monitoring, reduce the duration and cost of hospital admissions, and provide the convenience for dental procedures, which can be completed entirely on an outpatient basis.
Although there are isolated cases of postextraction hemorrhage, many of these cases involved full-mouth extractions and alveoplasties, and some of the patientsí anticoagulation levels exceeded therapeutic levels.²² When following current recommendations, only about 1% of patients experienced a significant postoperative bleeding episode.^18,22,23 All of these episodes were controllable with local measures. Never-theless, the level of anticoagulation, risk of bleeding from the procedure, risk of thromboembolism, and the patientís overall systemic health must be considered. For example, patients with a mechanical heart valve, atrial fibrillation with a history of stroke, and individuals with hypercoagulable disease states are at high risk for thromboembolism.

Table 3. Clinical Trials Studying Continuous Anticoagulation and Dentoalveolar Surgery Summarized by Beirne.18

Wahl, et al (1998) 2,014 surgical procedures 12 bleeds INR 2 – 4.0 5 had INR > 4 Blinder, et al (1999) 359 extractions 11 bleeds INR 1.5 – 4.0 Martinowitz, et al (1990) 63 extractions 0 bleeds INR 2.5 – 4.0 Bodner, et al (1998) 69 extractions 0 bleeds INR 2.0 – 4.0 Zanon, et al (2003) 250 pts 7 bleeds Compared INR  > 2 with< 2 (4 pts versus 3 pts) Carter, et al (2003) 152 extractions 0 bleeds INR 2.0 – 4.0 Campbell, et all (2000) 12 pts 0 bleeds INR 2.0

Numerous investigators have shown that modification of anticoagulant medication is not necessary when performing routine dentoalveolar surgery. An article by Beirne¹⁸ summarizes these clinical studies (Table 3). The article concludes that, “Stopping warfarin with or without bridging is not supported by clinical evidence. The risk of developing life-threatening bleeding that cannot be controlled using local measures following dental extractions, alveoplasties, or dental implants is so low that there is no need to stop warfarin.”

MAINTAINING HEMOSTASIS

Table 4. Commercial Agents Available to Aid in Control of Bleeding.

Gelfoam (Pfizer)   CollaPlug (Integra LifeSciences) Surgicel (Johnson & Johnson) Bone Wax (Ethicon) Tranexamic acid (Cyklokapron [Pharmacia & Upjohn Company]) ActCel (Coreva Health Sciences) BloodSTOP (LifeScience PLUS)

With the recommendation not to alter anticoagulant therapy for patients requiring routine dentoalveolar surgery, dentists must adhere to meticulous surgical technique, have the skills to ensure proper wound closure, and be familiar with the adjunctive hemostatic techniques (Table 4). Prior to performing surgery, it is recommended that the dentist obtain the appropriate laboratory values that assess coagulation.²⁴

Figures 3a and 3b. Pretreatment status of a patient taking Coumadin prior to extraction of these 2 maxillary teeth.

Figures 4a and 4b. Extraction and immediately after extraction, anticoagulated condition can be appreciated in Figure 4b.

Figures 5. Excellent hemostasis is achieved with local measures. (Same patient as in Figure 4.)

For the anticoagulated patient, applying pressure is still an excellent initial step in obtaining hemostasis. This approach will probably not be sufficient by itself. Even if hemostasis is obtained in the dental office, the surgical site is likely to be disturbed as the patient eats or speaks, thus requiring an after-hours appointment to re-establish hemostasis. At a minimum the dentist should consider using a resorbable gelatin sponge (Gelfoam [Pfizer]) inserted into the extraction socket prior to suturing (Figures 3 through 5). Gelfoam acts as a mechanical matrix to facilitate clotting. Resorbable oxidized cellulose (Surgicel [Johnson & Johnson]) is also well-known to dentists and is used similarly to Gelfoam. It should be noted that any type of packing material can be a nidus for infection, and caution in the use of these products should be the rule when operating in an infected area.²⁵
Hemostatic collagen (Colla-Plug [Integra LifeSciences]) provides a mechanical ma-trix, and when in contact with blood the collagen causes aggregation of platelets. This material is also resorbable within 14 to 56 days. Other products that can be used include bone wax, thrombin soaked gauze, and fibrin sealants.
Tranexamic acid 4.8% solution  (Cyklokapron [Pharmacia & Upjohn Company]) is a topical antifibrinolytic that is commonly used to prevent excessive hemorrhage during surgery. The patient is instructed to rinse with 10 mL of the solution for 2 minutes, 4 times a day for 7 days. This adjunctive therapy is not necessary for routine treatment, but may be useful in cases involving multiple extractions.16 Preordering with the pharmacy is often necessary to be certain this drug is in stock.
ActCel (Coreva Health Sciences) and BloodSTOP (LifeScience PLUS) are new products made from specially treated sterilized cellulose that dissolves within 1 to 2 weeks of placement within the extraction socket. The material expands to 3 to 4 times its original size and is quickly converted to a gel. ActCel is hypoallergenic and bacteriostatic. The material is placed into the socket in a manner similar to Surgicel. ActCel works by a variety of mechanisms. It provides increasing surface area for clotting, enhances platelet aggregation, and makes calcium ions more available for the clotting cascade.²⁵

CONCLUSION

Figure 6. Preoperative radiograph of mandibular teeth requiring extraction. Even with meticulous surgical technique, a potential exists for minor complications following routine dentoalveolar surgery.

The recommendations for performing dental treatment on patients receiving anticoagulation medication have been clarified. Each patient must be evaluated individually, and the dentist should communicate often with the physician managing the anticoagulant therapy. Each case should be reviewed for the risk of bleeding during the dental procedure (Figure 6) if anticoagulation is continued versus the risk of thromboembolism if anticoagulation medication is reduced, altered, or stopped. Patients who require restorative procedures, periodontal scaling, or simple exodontia should continue their anticoagulant medication. When surgical procedures are more extensive, the dentist must be aware of the available hemostatic agents and keep in close contact with the patient to provide rapid follow-up if a complication occurs. It is advisable to check the pretreatment INR when bleeding is anticipated. Evidence indicates that for routine, in-office oral surgery procedures, anticoagulant medication should be continued if the INR is within the therapeutic range and proper local hemostatic measures are used.

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References

1 Little JW, Falace DA, Miller CS, et al. Bleeding disorders. In: Dental Management of the Medically Compromised Patient. 6th ed. St Louis, Mo: Mosby; 2002.
2. Meehan S, Schmidt MC, Mitchell PF. The International Normalized Ratio as a measure of anticoagulation: significance for the management of the dental outpatient. Spec Care Dentist. 1997;17:94-96.
3. Troulis MJ, Head TW, Leclerc JR. Dental extractions in patients on an oral anticoagulant: a survey of practices in North America. J Oral Maxillofac Surg. 1998;56:914-917.
4. Abebe W. An overview of herbal supplement utilization with particular emphasis on possible interactions with dental drugs and oral manifestations. J Dent Hyg. 2003;77:37-46.
5. Ang-Lee MK, Moss J, Yuan CS. Herbal medi

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