CASE REPORT
A 45-year-old female patient presented to department of prosthodontics, Istanbul University, for prosthodontic treatment of the missing maxillary left posterior region (Figure 1). Clinical photos (Figures 2a and 2b), radiographic (Figure 3) examination, and mounted diagnostic casts (Figure 4) showed severe alveolar extrusion of the maxillary left posterior segment and a slightly reduced vertical dimension of occlusion (VDO).

Figure 1. Partially edentulous maxilla.

Figure 2a. Preoperative smile.	Figure 2b. Intraoral view of the reduced interocclusal space.
Figure 3. Panoramic radiograph prior to treatment.	Figure 4. Reduced interocclusal space, as observed in the mounted casts.

The treatment was started by increasing the VDO by adjustment of the occlusal plane of the mandibular teeth. A Chromascope Shade Guide (Ivoclar Vivadent) was used to select an appropriate shade, and then the worn mandibular right posterior teeth were prepared with supragingival shoulder margins for ceramic onlays. Preparations were made using an inlay/onlay preparation set (Inlay Preparation Set 4261 [KOMET/Brasseler]). Next, the mandibular left posterior teeth were prepared for ceramic crowns and a definitive impression of the tooth preparations was made using a vinyl polysiloxane (VPS) impression material (Brecision [Bredent]). The impression of the opposing arch was made with an irreversible hydrocolloid (Xantalgin [Heraeus Kulzer]). Three ceramic onlays (Figure 5) and a 3-unit metal ceramic bridge with metal occlusal surfaces (in order to gain interocclusal distance) were fabricated in the dental laboratory. After checking the occlusion and aesthetics, the ceramic onlays were cemented using dual-cure resin cement (NX3 Nexus Third Generation [Kerr]) and the 3-unit metal ceramic was cemented using a polycarboxylate cement (Poly F Plus [DENTSPLY DeTrey GmbH]). After the restoration of the mandibular teeth, the prosthetic treatment of the left maxillary edentulous area was planned. It was not possible to restore the left maxillary edentulous area with a fixed or removable prosthesis due to missing interocclusal space. Therefore, insertion of 3 dental implants after regaining the adequate interocclusal space by a maxillary alveoloplasty would be performed.

Figure 5. Fabricated ceramic onlays shown on the cast.	Figure 6. Alveoloplasty, before the insertion of implants.
Figure 7. Intraoral view of the implants immediately after surgery.	Figure 8a. View of the regained inter­occlusal space.
Figure 8b. Panoramic radiograph after the insertion of implants.	Figure 9. The implant positions shown on the cast.
Figure 10a. Final view of the patient.	Figure 10b. Cemented ceramic onlays.

A crestal incision throughout the maxillary left edentulous area and vertical releasing incisions were made. A mucoperiosteal flap was elevated buccally and lingually. Following the alveoloplasty (Figure 6), 3 dental implants (Swissplus [Zimmer Dental]) were placed according to manufacturer’s instructions. One stage surgery was chosen; the implants were supplied with healing abutments, and mucoperiosteal flaps were sutured with a close adaptation of the wound margins to the implant shoulders (Figure 7).
Four months later (Figures 8a and 8b) the gingiva formers were unscrewed and a definitive impression was made using VPS material (Brecision). Three separate metal ceramic crowns were fabricated on the model (Figure 9) and cemented on the 3 maxillary implants.
The patient was instructed in maintenance and hygiene procedures associated with the fixed dentures. The routine recall appointments were scheduled on a 6-month basis and no complications occurred during the 4-year follow-up period (Figures 10a and 10b).

DISCUSSION
The prosthetic rehabilitation of partially edentulous patients can engender a challenge for the clinician when there is reduced and inadequate interocclusal space. The occlusal scheme may be deformed due to early loss of teeth when the opposing dentition supraerupts towards the edentulous space.⁴ The extrusion of opposing teeth and/or the alveolar extrusion of the edentulous areas reduce the space needed for fabricating the partial denture.⁴ Before any prosthetic reconstruction can commence, lost intermaxillary space must be regained.³ Restoring the accurate plane of occlusion can be accomplished by periodontal, orthodontic, conservative restorative, and surgical procedures. Conservative treatment options like no treatment, intruding the mandibular posterior teeth, or periodontal surgery in combination with endodontic treatment were not chosen for the case presented in this article. Since sufficient bone for alveoloplasty was available in the maxillary edentulous area, the plane of occlusion in the mandible was corrected by a conservative approach.¹⁰ The mandibular right posterior teeth were restored with ceramic onlays, a relatively conservative treatment option, when compared with the alternative choice of full-coverage crown restorations.¹¹ The mandibular left posterior teeth were restored with a ceramic bridge because the teeth had been prepared prior to treatment in our clinic.
The use of dental implants to replace missing teeth has become the standard of care for edentulous spaces. With the presence of restricted interocclusal clearance, screw-retained restorations have been proposed because it may not be possible to develop adequate retention to retain restorations on implants with cement.^5,12 Screw-retained restorations can be secured to implants with as little as 4 mm of space from the surface of the implant to the opposing occlusion.¹² However, if the crown length is too short, it may negatively affect the aesthetics; especially when the crowns are in the smile line as in the patient presented in this report. The main reason why a screw-retained implant restoration was not necessary here was the sufficient coronal distance in the maxilla gained by doing the alveoloplasty. Alveoloplasty was performed before the insertion of the implants in the same surgical session without a requirement for a second surgery.

CLOSING COMMENTS
Limitation in interocclusal space is a common problem in prosthetic dentistry. Several approaches have been proposed to solve this problem. The treatment presented here involved a combined prosthetic and surgical approach in order to gain interocclusal distance allowing a functional as well as aesthetic result. A 4-year follow-up period showed the treatment chosen had provided for a successful and stable result.

References

1. Mopsik ER, Buck RP, Connors JO, et al. Surgical intervention to reestablish adequate intermaxillary space before fixed or removable prosthodontics. J Am Dent Assoc. 1977;95:957-960.
2. Lee HE, Lee KT, Tseng YC, et al. Interdisciplinary management of unfavorable posterior intermaxillary space. Br J Oral Maxillofac Surg. 2008;46:413-415.
3. Chun YS, Row J, Yang SJ, et al. Management of extruded maxillary molars to accommodate a mandibular restoration: a clinical report. J Prosthet Dent. 2000;83:604-606.
4. Chen CM, Tseng YC, Huang IY, et al. Interdisciplinary management of dental implant patient: a case report. Kaohsiung J Med Sci. 2004;20:415-418.
5. Armellini D, Bilko S, Carmichael RP, et al. Screw-retained prosthesis for Straumann implant sites with limited interocclusal clearance. J Prosthodont. 2006;15:198-201.
6. Chaimattayompol N, Arbree NS. Assessing the space limitation inside a complete denture for implant attachments. J Prosthet Dent. 2003;89:82-85.
7. Alsiyabi AS, Felton DA, Cooper LF. The role of abutment-attachment selection in resolving inadequate interarch distance: a clinical report. J Prosthodont. 2005;14:184-190.
8. Melsen B, Fiorelli G. Upper molar intrusion. J Clin Orthod. 1996;30:91-96.
9. Alessandri Bonetti G, Giunta D. Molar intrusion with a removable appliance. J Clin Orthod. 1996;30:434-437.
10. Bittner N, Lal K, Neurohr J. Fabrication of a custom abutment for a wide-diameter implant in a situation with limited interocclusal space. J Prosthet Dent. 2008;100:474-477.
11. Sorensen JA, Choi C, Fanuscu MI, et al. IPS Empress crown system: three-year clinical trial results. J Calif Dent Assoc. 1998;26:130-136.
12. Chee W, Jivraj S. Screw versus cemented implant supported restorations. Br Dent J. 2006;201:501-507.

     

Dr. Geckili earned his DDS from the Marmara University School of Dentistry (1999). He also holds a PhD in prosthodontics (2007) from the School of Dentistry, Istanbul University, Department of Prosthodontics, where he is currently a research assistant. He is a member of Academy of Prosthodontics and Gnathology Society, Turkish Society of Oral Implantology, and European Academy of Osseointegration. He is experienced in implantology and prosthodontics, has taught for more than 10 years, is a proficient lecturer, and has published more than 15 papers in peer-reviewed professional journals. He can be reached at geckili@istanbul.edu.tr.

Disclosure: Dr. Geckili reports no disclosures.

Dr. Bilhan earned his DDS in 1993; has a postgraduate certificate in oral surgery and implantology from the School of Dentistry, Karl-Franzens University of Graz, Austria (1994); and holds a PhD in oral surgery from the School of Dentistry, Zurich University, Department of Oral and Maxillofacial Surgery (1996). In 2004, he received a PhD in prosthodontics from School of Dentistry, Istanbul University, Department of Removable Prosthodontics, where he is currently a research assistant. He is a member of Academy of Prosthodontics and Gnathology Society, Turkish Society of Oral Implantology, a Fellow of the International Team for Implantology, a Fellow of International Congress of Oral Implantology, and a master of Implant Prosthodontics Section. His experience with implantology, prosthodontics, and oral surgery includes extensive clinical experience with more than 10,000 successfully performed oral surgeries. He has taught for more than 14 years and has published more than 34 papers in peer-reviewed professional journals. He has extensive international lecture experience with multilingual capabilities (fluent in Turkish, German, English, and intermediate level French). He can be reached via e-mail at bilhan@istanbul.edu.tr.

Disclosure: Dr. Bilhan reports no disclosures.

Dr. Mumcu holds a DDS from Istanbul University School of Dentistry (1998) and a PhD in Prosthodontics (2006) from School of Dentistry, Istanbul University, Department of Removable Prosthodontics (2006), where he is also a research assistant. He holds memberships in the International Association for Dental Research, Academy of Prosthodontics and Gnathology Society, Turkish Society of Oral Implantology, European Academy of Osseontegration, International Team for Implantology, the Assocication of Prosthodontics, American College of Prosthodontists, Association of Prosthodontics of Canada, and the European Association for Osseointegration. He is experienced in implantology, prosthodontics, and temporomandibular disorders. He is a proficient lecturer, has taught for more than 12 years, and has published more than 32 papers in peer-reviewed professional journals. He can be reached via e-mail at emremum@yahoo.com.

Disclosure: Dr. Mumcu reports no disclosures.

Figure 1. Retracted preoperative photo with partial denture.

Figure 2. Retracted preoperative photo without partial denture.

Figure 3. Parallel pins for angulation.

Figure 4. Biohorizons implants placed.

Figure 5. Panoramic radiograph of implants placed.

Figure 6. Placement of bone grafting material.

Today, many practices across the United States are experiencing changes in their practices. There have been increases in no-shows/cancellations and challenges in keeping the treatment schedule full. In today’s economy, more patients than usual are expressing concerns about the status of the economy and how long this recession will last.
During this economical recession, tens of thousands of autoworkers have lost their jobs here in Michigan. The primary concern for most of these patients is not their oral health, but how they will provide for their families and put food on the table. Many of these patients tend to disappear from the practice only to return for emergency dental care.
      One population that has been overlooked or avoided by many general dentists is denture wearers. For one reason or another, the denture patient has caused many frustrations for the providing dentist, especially in regards to the mandibular denture. Conventional mandibular dentures for patients with severely atrophic mandibles oftentimes present problems of retention, phonetics, function, and pain due to instability.
      Endosseous implants have been successfully used to restore edentulous mandibles with implant-supported fixed bridges, hybrid prosthetic dentures, and removable overdenture prostheses. Many completely edentulous patients desire a fixed restoration rather than a removable prosthesis. “A fixed restoration provides the psychological advantage of acting and feeling similar to natural teeth, whereas an overdenture, even if fully implant supported, remains a removable prosthesis.”¹ This article focuses on restoring a patient with a fixed lower bridge supported by implants.

CASE REPORT
Diagnosis and Treatment Planning
A 67-year-old man presented to our office with a partially edentulous mandible, complaining about the instability of his lower partial denture (Figure 1). The patient was in good health and a nonsmoker. Although some wear facets were noted on the mandibular canines, the patient did not have signs of severe bruxism (Figure 2). In the maxillary arch, he had an existing denture that was approximately 13 years old. On the lower arch, the remaining dentition was comprised of 2 canines (teeth Nos. 22 and 27) and a lower right premolar (tooth No. 28). The patient complained that the right distal portion of the partial had broken off, and that it never really fit very well from the beginning.
      Preoperatively, it was important to analyze jaw size, bone volume/density, jaw relations, and interocclusal distance. A panoramic radiograph was also taken to evaluate the positions of the mandibular canal and mental foramina. Upon clinical examination and radiographic interpretation, it was apparent that the patient had sufficient bone in the anterior portion of his mandible for the placement of 5 endosseous dental implants. In fact, by maintaining the remaining anterior teeth for all these years, and not having them all removed and a denture placed, bone was preserved.
      The consultation with the patient focused on the advantages of having the ability to restore the lower arch with implants and a fixed bridge. Some of these advantages would include: the psychological effect (“feels like teeth”), less prosthetic maintenance with relines and/or attachment wear, less food entrapment, and maintaining posterior bone. Once the patient was educated in these advantages, he quickly agreed to the proposed treatment plan: fabrication of a new upper complete denture; extraction of teeth Nos. 22, 27, and 28; alveloplasty; bone grafting; and placement of 5 dental implants and a fixed bridge.
      Impressions utilizing a polyvinylsiloxane (PVS) material (Take 1 Advanced, Medium Body [Kerr]) were taken of both maxillary and mandibular arches with corresponding bite registration in centric occlusion, so that the lab could fabricate a diagnostic wax-up. In order for the patient to have teeth on the day of surgery, an immediate denture was fabricated for the mandibular arch. Also, a wax trial denture was fabricated to check relations between upper and lower arches. The aesthetic and functional (fit and bite) parameters were then approved by the patient.

Implant Surgery
One hour before the surgery, the patient was premedicated with amoxicillin (2.0 g), dexamethasone (4 mg) and diazepam (5 mg). Local anesthesia (lidocaine [Henry Schein] HCL 2% with 1:100,000 epinephrine) was also administered. Using periotomes and luxators (Dental USA), the remaining lower teeth were extracted. Then, a crestal incision was made, from the position of the right first molar to that of the left first molar. The mandible was exposed, and the mental foramina were identified. The crestal bone in the anterior region was reduced, under profuse irrigation with sterile saline solution, to create a 4- to 5-mm wide bone platform to accommodate the dental implants. A clear duplicate of the immediate lower denture with 3 radiopaque markers (Premise Flow [Kerr]) was seated. Then, a panoramic radiograph was taken to further identify the relationship of the proposed treatment and location of the mental foraminae/mandibular nerve.
      The arch form and the position of the mental foraminae are important criteria when placing implants in the anterior segment to replace the entire mandibular arch. “The anterior arch form and foraminae position affects the position of the distalmost implants and the anterior arch form (square, oval, or tapering) is relative to the anteriomost implant position. The distance from the center of the most anterior implant to a line joining the distal aspect of the 2 most distal implants on each side is called the A-P Distance, or the A-P Spread. The greater the A-P Spread, the further the distal cantilever may be extended to replace the missing posterior teeth.¹

Figure 7. Transmucosal healing abutments. Figure 8. Full-arch polyvinylsiloxane impression (Take 1 Advanced Super Fast [Kerr]). Figure 9. Upper denture. Figure 10. Lower fixed bridge. Figure 11. Occlusal postoperative photo of seated bridge. Figure 12. Retracted postoperative view.

     “The most common number of implants used today in the Bränemark treatment option is 5. This number allows as great an A-P Spread as 6 implants, with greater inter-implant distance, so that if bone loss occurs on one implant, the loss would not automatically affect the adjacent implant site.”¹ As a general rule, when 5 implants are placed in the anterior mandible between the foramina, the cantilever should not exceed 2.5 times the A-P Spread, with all other force factors being low.
      Utilizing the BioHorizons surgical kit, a 2.0 mm starter drill was placed into the central site and advanced to a depth of 10 mm, measuring from the bone surface. A parallel pin gauge was placed in the site of the osteotomy, and then a radiograph was taken to evaluate the osteotomy position and angle. Once verified for angulations, the remaining implant areas were prepared in the same manner (Figure 3). Following the 2.0 mm starter drill, a 2.5 drill (with stop) was used to increase the osteotomy depth and width. Next, in the anterior 3 locations, the length of the osteotomies was extended to 15 mm and the 2 most distal sites were extended to 10.5 mm. After getting to depth with the 2.5 mm drill, larger sized drills (0.5 mm increments) were used to widen the osteotomies, so that 4.0 mm x 15 mm implants were placed in the anterior 3 positions, and 5 mm x 10 mm implants were placed in the most distal sites (Figure 4). This gradual removal of bone reduces heat generation in the surrounding tissue. The cutting flutes of this system extend the length of the drill body and collect bone that may be saved for intraoperative grafting procedures. At this point, one more panoramic radiograph was taken to verify the positions of the implants (Figure 5).

Once the position of the implants was confirmed, the 3inOne Abutments (BioHorizons) used for driving the implants into the osteotomy were removed and replaced with transmucosal healing abutments. Soon afterwards, the remaining extraction sites were grafted with Beta Tri-Calcium Phosphate (Cerasorb [Riemser]) (Figure 6) and covered with a membrane (Epiguide [Riemser]). The soft-tissue flap was then re-adapted over the ridge, allowing the transmucosal abutments to protrude for single-stage surgical protocol. The flap was then closed with 4.0 PGA polyglycolic acid synthetic absorbable sutures (Salvin Dental Specialties). 

      Following the surgery, the new upper denture and lower immediate denture were tried-in for accuracy and pfit. The lower immediate denture was relieved in the areas of the transmucosal abutments, and then relined with a soft reline material (GC Reline [GC America]). The patient was asked to return the next day for a postoperative visit, and then again in a week for another postoperative visit. At both appointments, the patient stated he felt well, and that he had not experienced any severe pain following the surgery.

Work Begins on the Final Prosthesis
Five to 6 months after the surgery, the patient presented for impressions for the final fixed prosthesis (Figure 7). The transmucosal abutments were removed, and the 3inOne Abutments were placed with ball top impression screws into the implants. A full-arch PVS impression (Take 1 Advanced Super Fast [Kerr]) (Figure 8) was taken using a stock plastic tray (Vista Dental Products). In addition, a full-arch bite registration (using sideless triple-function trays [GC America]), and an AlgiNot (Kerr) impression of the opposing denture, were taken. The dental laboratory team then fabricated the complete upper denture utilizing BlueLine (Ivoclar Vivadent) teeth (Figure 9).

Try-in Appointment
The lower PFM fixed restorations were also fabricated, and returned to our office in a bisque-baked stage for try-in. When the patient returned for a try-in appointment, he was immediately pleased when we placed the new upper denture. Next, the prepared 3inOne Abutments and the PFM bridge were tried-in; as a result of observations made during the try-in, the dental laboratory technician was instructed to shorten the incisal edges of this restoration approximately 1.0 mm, and to then complete the technical work on the restoration.

Final Delivery
At delivery, the abutments were connected to the implants by fastening the titanium retaining screws with the torque wrench to 20 Ncm. Radiographs were taken to ensure that the abutments were fully seated. The fixed partial denture (Figure 10) was then tried-in to verify marginal adaptation and fit. Once a radiograph was taken to verify the complete seating of the restoration, any necessary occlusal adjustments were made and polished.
The exterior portion of the fixed partial denture was coated with a separating medium, and the restoration was cemented with Maxcem Elite (Kerr), a self-etching resin cement. Excess cement was easily removed from the margins (Figure 11) before final curing with the Demi curing light (Kerr) for 20 seconds. No finishing of the cement was necessary along the margins. The overall health and structure of the soft tissue and restorations were very good. The patient was extremely satisfied with the definitive results (Figure 12) and was given oral hygiene instructions to do at home and given a follow-up schedule.

CONCLUSION
No provider wants to convert a patient who is partially to fully edentulous without planning for stability and retention in the final prosthesis. Although overdentures help in alleviating a lot of the problems associated with dentures, they do not always fulfill every patient’s demands for function and comfort. There are numerous prosthetic options to restore the completely edentulous mandible. One of these options involves the use of dental implants and a fixed complete denture. If the remaining bone permits, placing dental implants and restoring with a fixed partial denture allows the patient to function without pain and discomfort. Most of all, implementing this type of treatment option not only satisfies the patient’s aesthetic, functional, and psychological needs, but it also preserves bone.F

Acknowledgement
The author wished to thank Scott Ward (Ward Dental Lab [a DTI Laboratory] in Brighton, Mich) for the fabrication of these restorations, and Dr. Carl Misch for his mentorship in implantology.

Related Study
Dental practitioners interested in implants should consider post-graduate teaching institutions like the Misch Institute (misch.com), and organizations like the International Congress of Oral Implantologists (icoi.org) for more information and training.

Reference

1. Misch CE. The completely edentulous mandible: Treatment plans for fixed restorations. In: Misch CE. Contemporary Implant Dentistry. 3rd ed. New York, NY: Mosby (Elsevier); 2007: 327-364.

Dr. Nazarian maintains a private practice in Troy, Mich, with an emphasis on comprehensive and restorative care. He has earned a Fellowship and Mastership in the International Congress of Oral Implantologists, and his articles have been published in many of today’s popular dental publications. He is the director of the Reconstructive Dentistry Institute. He has conducted lectures and hands-on workshops on aesthetic materials and dental implants throughout the Untied States, Europe, New Zealand, and Australia. He is also the creator of the DemoDent patient education model system. He can be reached at (248) 457-0500 or via the Web site aranazariandds.com.

Disclosure: Dr. Nazarian reports no conflicts of interest.