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Discover a wealth of insights as Dr. West unveils innovative techniques complemented by meticulously documented protocols. Through an engaging and lighthearted approach, he will demonstrate how these techniques seamlessly integrate into modern endodontic procedures, ensuring optimal patient outcomes.

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Nonsurgical endodontics is the only dental discipline where the dentist cannot simultaneously see and do treatment.

The mechanics of endodontics are performed in a dark and often lonely space. This unknowingness of “drilling into a patient’s head” is nerve-racking, unsettling, fearful, and one of dentistry’s biggest stressors. However, according to the Greek philosopher Heraclitus, “The only constant in life is change,” and today, innovative change is aiding dentists in reducing the anxiety of doing endodontics. This article reviews 9 recent-past, present, and future innovations that are transforming endodontics to be easier and more predictable. What this means to us as dentists is more confidence, consistency, and control during the endodontic experience. When this is all added up, endodontics begins to change from fear to fun!

WHAT IF?

“Humans are the only animals that build machines.”¹ 

By doing so, we expand our capacities beyond our biological limits. Tools turn our hands into more versatile appendages. Innovations are indirectly and directly enabling dentists to have proof that we have successfully cleaned, shaped, and obturated the root canal system. Mechanical endodontic shaping systems now create specific radicular preparations with extreme accuracy even though we cannot directly inspect the preparation itself. Microscopes and 2D and 3D digital imaging currently permit dentists to see the previously unseen. Every day, new devices intended to improve 3D irrigation, agitation, and cleaning flood the endodontic market with a “mine is better than yours” mantra. New innovations may tell the 3D cleaning truth. Soon, we will be able to detect tooth cracks and restorative micromovements previously invisible through visual or symptom-duplicating tests. This breakthrough innovation alone would provide early detection and immediately reduce potential catastrophic restorative consequences.  

Since endodontics was recognized by the ADA as a specialty in 1964, endodontists, engineers, inventors, and dental companies have been innovating to improve root canal system cleaning; preparing a solid root canal system replacement; and, in effect, produce an impervious endodontic seal.²

The oral cavity has an astonishing 40 billion bacterial inhabitants. It could only take a few million of them to feed and flourish off of nutrient-latent diseased endodontic anatomy contents to enable them to emanate from uncleaned and/or underfilled root canal system portals of exit (POEs) and cause an endodontic failure.

The purpose of this article is to examine what is in the near-past, present, and future horizon of humans building machines for inventing safer, easier, and more predictable endodontics. My disclaimer is the observations of these innovations are my own. As I have said to my audiences in the past, “The best education in the world is your own.” I invite the reader to thoroughly test and research my innovation evaluations and see if they fit for you. We are all different. All of us have a different mix of patients, different skill levels, practice different styles, and are at a different stage of our practice life.

1. What if detecting cracks in teeth or micromovement of existing tooth restorations without directly seeing them was possible?  

Every dentist has experienced the challenge of diagnosing breakdowns in teeth and implants. For example, a major reason clinicians have trouble diagnosing cracks in teeth and the elusive “cracked tooth syndrome” is having to rely on visual and clinical assessments, which simply do not pinpoint the diagnosis. Identifying cracks early in the “crack or restoratively damaged cycle” has been evasive as root cracks and restorative gaps most often begin as microns of separation and are not visible on radiographs, digital scans, CBCT, photographs, or clinical examination until later. Often, it is too late in the “crack or gap cycle” to restore the tooth. In addition, and most significantly, current diagnostic aides provide data about a tooth during a static moment in time when teeth are at rest vs dynamic movement. 

InnerView, a new diagnostic aide that is getting close to being released by Perimetrics, Inc, takes an engineering approach to evaluating the structural stability of teeth and implants. Using quantitative percussion diagnostics (QPD), gentle tapping on the facial side of a tooth allows a rod sensor to measure the amount of energy returned to the sensor with each tap. The information indicates if there are any oscillations in the tooth as measured by a sensor in the testing rod during the light impact. The more oscillations, the less structurally sound the tooth and the greater the probability that there is a crack in the tooth or breakdown in existing restorations. QPD testing simulates what happens when the patient is using his or her teeth during chewing or other parafunctional habits.³

Perimetrics has one of the largest databases in the world of damaged (cracked) teeth. Cracks are referred to as microgap defects (MGDs) and have more than 28 peer-reviewed publications about this revolutionary technology in dental, engineering, and science journals. It takes only 3 minutes to test an entire mouth and collect immediate results and only 3 seconds to test an individual tooth. 

We will be using our teeth longer than ever needed before in human history. Therefore, the requirement for this type of diagnostic instrument is growing exponentially. Humans are living longer, and we want our teeth in order to look good, smell good, feel good, and be successful. The rough estimate is that humans have 1 million significant teeth loading repetitions per year.⁴ This means that, for a 60-year-old “pounding” on permanent teeth for 50 years, his or her teeth have experienced 50 million impacts to date! It is no surprise teeth break and crack. Stay tuned to the InnerView System of locating MGD’s from cracks and failing restorations. This invention promises to change the way we see dentistry for years to come (Figure 1).

Figure 1. (a) InnerView device (Perimetrics) in clinical use. (b) Cordless handheld

2. What if, seeing chairside evidence, your cleaned, shaped, and conefit root canal system preparation is 3D cleaned of any pulp, nerve tissue, apical fluid, blood, and/or bacteria?  

The purpose of endodontics is to prevent or heal lesions of endodontic origin (LEOs). The rationale of endodontics is that nature has the capacity to prevent or heal these LEOs 100% of the time if the root canal system has been eliminated as a source of endodontic disease.^4,5 For several years, there has been a raging debate that “My instrument cleans root canal systems better than yours.”  In the past, there has been little comparative proof for these claims. A soon-to-be-released chairside device called the Endocator  claims to quantify in 10 seconds how clean the root canal system is and give chairside feedback about the effectiveness of your shaping system, disinfection protocol, and activation.⁶ The device promises to tell the accuracy of the patient’s root canal cleanliness (cellular debris). Operating on a multi-biomarker detection mechanism, the most pivotal of which is adenosine triphosphate (ATP), the Endocator boasts universal applicability. ATP’s ubiquity in every living organism renders this instrument suitable for vital, nonvital, and retreatment endodontic patients (Figure 2). 

Figure 2. Endocator chairside biomarker.

3. What if seeing proximal caries 20% more accurately with RVG sensors and minimizing metal artifacts in CBCT scans were both already available?

Diagnosing interproximal caries at the earliest possible stage is key to taking advantage of minimally invasive restorative techniques. Radiographs, whether they are analog or digital, typically do not accurately show interproximal caries until the caries penetrate 30% to 40% of the enamel. Carestream Dental offers Logicon caries detector software used with RVG intraoral sensors to aid dentists in accurately predicting interproximal caries in enamel and dentin.^7,8 We are now also seeing a new wave of products that are using artificial intelligence (AI) technology to help us read radiographs. All of these products will surely revolutionize our diagnostic capabilities.

Metal in CBCT scans can cause scatter, which can make it difficult to identify and diagnose pathology or the restorative foundation status. In endodontic retreatment, metal scatter often makes it impossible to unravel if the metal is a post, silver cone, or even the outline of a crown. Carestream Dental provides a novel innovation to solve this situation. It is called the Metal Artifact Reduction (MAR) algorithm—CS MAR—and is available with its CBCT systems, such as the CS 9600, CS 8200 3D, and CS 8100 3D, which assists practitioners in applying the algorithm before or after taking the scan. Carestream Dental’s software allows the user to toggle between the CBCT scan and the CS MAR filter while reducing the risk of missing filtered-out structures (Figure 3). 

Figure 3a.

Figure 3b.

Figure 3c.

Figure 3d — Figure 3. (a) Carestream Dental 9600. (b) Bite-wing of a maxillary right first molar without Logicon (Carestream Dental). Note, distal caries is vaguely perceived. There is no radio- graphic evidence of mesial caries. (c) The Logicon closeup (red markings), however, clearly outlines easily missed distal caries as well as previously unperceived mesial caries. (d) Left image metal scatter camouflages the mesial incisal fracture and discriminating anatomy around the post of this lateral incisor. The right image reveals improved Metal Artifact Reduction clarity.

4. What if we were able to capture and see 3D imaging at chairside? 

Three-dimensional chairside imaging units now give dentists more data than 2D ones without the patient leaving the operatory. Seeing 3D images at chairside could be like having superhero eyes. 

The innovative product Portray Xray has become a significant positive change for any practice looking to improve its imaging diagnostics over current, traditional 2D imaging. This imaging device utilizes a technology called 3D intraoral tomosynthesis, which integrates improved hardware and intuitive software with minimal radiation and no change in workflow.⁹ The imaging head has 7 imaging units vs a traditional single unit. The software divides the volume into 0.5-mm slices, providing a virtual dissection of each tooth, and the Synthetic 2D mode gives the clinician the ability to rotate the image to see into interproximal spaces. The Portray system was specifically designed to allow dentists to see more caries, fractures, and root structures that may not be visible in a standard x-ray (Figure 4). 

Figure 4. Portray chairside 3D Imaging. The left image of a mandibular left molar is unremarkable. The right chairside 3D image, however, divulges obvious mesial root resorption. While Portray is not designed to replace CBCT, it may indeed someday replace 2D chairside imaging.

5. What if “feeling vs seeing” clinical microgaps and extremely narrow endodontic orifi was significantly improved for the endodontic clinician and endo/perio probings were more accurate and comfortable for the patient? 

In endodontics, smaller is better. The English proverb, “Necessity is the mother of invention,” inspired me to think everything in endodontics needs to be smaller. Micro explorers and periodontal probes have been an essential part of our private endodontic practice for several years but only recently have been perfected. The JW 17 Standard and Signature Series Micro Explorer and Micro Endo/Perio probe (DoWell Dental Products) are valuable for every endodontic clinician. At half the size of the standard DG 16, the explorers are really “feelers” in identifying tiny orifi, and the JW microprobe allows for accurately identifying vertical fractures compared to the wider periodontist’s favorite Marquis probe (Figure 5). 

Figure 5a.

Figure 5b.

Figure 5c — Figure 5. (a) The arrow points to Mueller bur (Brasseler USA) compressed hydroxyapatite (endodontic clinicians call this the “white spot”) into a calcified central incisor canal and identifying the canal’s entrance. (b) Graphic comparison of DG 16 further blocking the canal vs the narrower JW Micro 17 piercing the compacted hydroxyapatite. (c) From left to right: JW Signature Micro Explorer, JW Standard Micro Explorer, and JW Micro Endo/Perio probe.

6. What if an endodontic rotary system required no hand files 50% to 80% of the time, produced a simultaneous “slender body” and “deep shape” with only 3 files, and had a successful conefit 100% of the time? 

Dentsply Sirona’s ProTaper Ultimate Shaping System and Conform Conefit precision machine-made gutta-percha cones have achieved the shaping technology to produce a “deep shape,” providing 3D cleaning and 3D obturation while maintaining minimally invasive, appropriate body preparations.¹⁰ Sounds too good to be true? Well, it is too good, and it’s true! (For 100% conefit, root canal preparations must be cleaned of any obstructive debris.)

The technique is as easy as 1, 2, 3: one Slider; one Shaper; and, in many cases, one Finisher. This innovation, which took 2 years to develop, is especially beneficial in longer, thinner, and more curved canals. It is critical to note that when a slider does not follow to length easily, a manual Glidepath (Slidepath) is a prerequisite. Always read DFUs first!

As one of the designers, our biggest challenge was to continue the illustrious legacy of ProTaper by simultaneously breaking new ground while always maintaining being true to ProTaper values. Design is so much more than just simply designing a system that produces predictable shapes. It is about maintaining a brand of optimal performance (Figure 6). 

Figure 6a.

Figure 6b.

Figure 6c — Figure 6. (a) Dentsply Sirona ProTaper Ultimate Shaping System and Conform Fit gutta-percha cone. The image compares ProTaper Gold Finisher 1 vs the narrower body ProTaper Ultimate Finisher 1 while maintaining essential “deep shape” for 3D Cleaning and 3D Obturation. (b) Illustration of a maxillary molar DB canal demonstrating precision-machined Conform Conefit, which occurs 100% of the time if the funnel form radicular preparation is thoroughly clean of any debris. (Image courtesy of Advanced Endodontics, Santa Barbara, Calif.) (c) Typical ProTaper Ultimate radiographic “look” with “narrow body” and “deep shape.” (Image courtesy of Dr. Reid Pullen, Brea, Calif.)

7. What if you could see down a root canal system and identify anatomy such as blocks, ledges, transportations, perforations, lateral POEs, broken instruments, and retreatment conditions?

Introducing the future Endoscope, which is early in its development stages. As an endodontist, one of my most significant stressors is doing endodontics in the dark. My fantasy has always been to visually see deep inside a canal and determine what obstacles are present, such as broken files, blocks, ledges, transportations, or failing obturation materials and where they are. I call this the Small Space Race and invite the reader to join in! Eric J. Seibel, PhD, research professor, mechanical engineering and director of the Human Photonics Laboratory at the University of Washington, is explorating the use of the technology for viewing the root canal system. Contact him at eseibel@uw.edu. 

The imaging of adult root canal systems before and after shaping has been limited by the sub-millimeter inner diameter size. Commercial ultrathin endoscopes based on coherent fiber bundles do exist, such as the 0.5-mm-diameter Fujikura FIGH-10-350S, but their low number of imaging pixels, fragility, and semi-rigid shafts have limited their use in healthcare.^11,12 Two new scanning flexible endoscope designs under development for sub-millimeter-diameter clinical products are rotating a single optical fiber that produces a line of pixels with an optical grating at the fiber tip, called a spectral-encoded endoscope,¹³ and vibrating a single optical fiber with a microscanner at the tip, called a scanning fiber endoscope.¹⁴ Alternative new designs from academia use sophisticated computer algorithms to generate images through a single multimodal optical fiber (<0.5-mm diameter) without scanning, which is called various names depending on the academic lab developing the technology, such as spatial-frequency tracking adaptive beacon light-field encoded endoscope and sense.¹⁵

Futuristic designs from academia that use sophisticated computer algorithms to generate images through a single multimodal optical fiber (<0.5-mm diameter) may sooner than later allow us to see what has never been seen before (Figure 7). 

Figure 7. (a) Micro Endoscope seeing a lateral portal of exit (POE) several millimeters from the apical POE. (b) The Pilot Endoscope set up in its early development.

8. What if a simple addition to your microscope improved the clinical team’s diagnostic treatment mechanics and raised the level of enjoyment during treatment? 

In 1683, Dutch researcher Anton van Leeuwenhoek ushered in a new age of science when he peered through a hand-ground lens and, for the first time, described a living cell.¹⁶ Approaching 3.5 centuries later, dentistry is still discovering the microscope as a means of coaxial magnification (common light and visual axis), which eliminates disturbing shadows, no longer tethers the dentist to a headset, and grants the patient co-observation and understanding of the clinical diagnosis and treatment.¹⁷

Doing endodontics can be a lonely experience. The clinician is frequently the only person who is aware of how his or her endodontics are progressing during the actual endodontic treatment. The assistant is often excused because there is no presumed need for participation. The dentist is the only one who can see and do the treatment. In addition, just sitting chairside with an occasional request for saliva aspiration makes for a long and boring day.

The microscope-trained clinical team is literally seeing the patient’s endodontic tooth with 4 eyes! The assistant anticipates what is technically next more accurately, gives honest guidance, and adds enormous energy and encouragement, such as “We can do this,” because they can see the situation. This is all authentic. But for me, the trained assistant’s intimate endodontic presence and the awareness that the Global Surgical Co-Observation System Microscope brings is crucial to experiencing a joyful, energizing, and fun day. Lastly, by seeing what we are doing together, we have a unique way to hold each other accountable for the practice’s level of performance (Figure 8). 

Figure 8. The Global Surgical Co-Observation System Microscope enables the dentist and clinical assistant to see the same image at the same time.

9. What if there were a “magic juice” that could more effectively remove the fatal flaw (dentin mud and collagen) of endodontics?

If this were true, the marquis skill of endodontics, “following” from orifice to radiographic terminus in order to prepare the Glidepath (Slidepath) would be easier. There has not been a novel endodontic irrigant introduced for a number of years. Cleaning the root canal system is challenging because anatomical crypts are complex, and the complete elimination of pulp tissue, microbial pathogens, calcifications, and miscellaneous debris is often a real clinical test.  

Endodontist Dr. Terry Pannkuk has explored the use of a trichloroacetic acid (TCA)-based irrigant to have enhanced benefits while performing endodontic treatment of external root resorption from an internal root approach. In his patented TCA-based solution, Terry has also observed an increase in the number of POEs radiographically visibly filled. These properties are currently being researched, and human clinical trials are being performed.

In addition, the following claims and benefits are being studied at the university level: hemostasis, calcific debris removal, smear layer removal, dehydration of the pulp, and facilitating digestion with sodium hypochlorite. 

These properties appear to reduce treatment time because of the efficient dissolving action. Small files are reportedly able to slip and slide into tight, narrow canals without early blockage, and apical preparations can be better cleared and dried before obturation, resulting in void-free, controlled flow (Figure 9). 

Figure 9. (a) This radiographic example demonstrates the power of cleanliness and 3D resistant form funnel-shaped canals. From left to right is the maxillary left second premolar pretreatment, downpack (note multiple POEs visibly filled), and finish images using trichloroacetic acid (TCA) as an adjunct irrigant agitated with the SmartLite Pro EndoActivator (Dentsply Sirona) and vertical compaction of warm gutta-percha obturation. (Image courtesy of Dr. Terry Pannkuk, Santa Barbara, Calif.) (b) Graphic of TCA delivery device.

CLOSING COMMENTS

The purpose of this article is to review 9 recent-past, present, and future innovations designed to enable the endodontic clinician to see direct and indirect information that brings us closer to the truth of endodontic diagnostic and treatment accuracy.

I have been an educator and have been called an endodontic clinical visionary for most of my professional career. However, I am just like you. I am compensated for my level of performance one patient at a time. For each of these patients, we have the knowledge, skills, and tools to be successful. The difference is our willingness.

This article introduces a small window into our innovativeness. The question, however, is always the same: “Will we show up?” Will we be present for this next patient’s treatment? Do we care? I care, and I believe that since you have read my article to this point, this is ample evidence that you care too. Together, we can and will impact our level of endo-
dontic mastery and craftsmanship. 

There will be more innovations in years to come. Some will be disruptive. The ultimate benefactor of our improved endodontic performance is the one that will never read this article and the one that matters the most: our patient. 

As endodontists, what’s in it for us is that our level of performance becomes even more predictable; easier; and, quite frankly, more fun!

REFERENCES

1. Domingos P. Artificial intelligence will serve humans, not enslave them. Scientific American. 2021;30(4):100–3.  

2. West JD. The relationship between the three-dimensional endodontic seal and endodontic failures. Master’s Thesis. Boston University; 1975.

3. Sheets CG, Quan DA, Wu JC, et al. An evaluation of quantitative percussion diagnostics for determining the probability of a microgap defect in restored and unrestored teeth: A prospective clinical study. J Prosthet Dent. 2023:S0022-3913(23)00272-X. doi:10.1016/j.prosdent.2023.04.016 

4. Schilder H. Vertical compaction of warm gutta percha. In: Gerstein H, ed. Techniques in Clinical Endodontics. W.B. Saunders; 1983:84-90.

5. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am. 1974;18(2):269–96.

6. Tan KS, Yu VS, Quah SY, et al. Rapid method for the detection of root canal bacteria in endo-
dontic therapy. J Endod. 2015;41(4):447–50. doi:10.1016/j.joen.2014.11.025 

7. Gakenheimer DC. The efficacy of a computerized caries detector in intraoral digital radiography. J Am Dent Assoc. 2002;133(7):883–90. doi:10.14219/jada.archive.2002.0303

8. Tracy KD, Dykstra BA, Gakenheimer DC, et al. Utility and effectiveness of computer-aided diagnosis of dental caries. Gen Dent. 2011;59(2):136–44. 

9. Mauriello SM, Broome AM, Platin E, et al. The role of stationary intraoral tomosynthesis in reducing proximal overlap in bitewing radiography. Dentomaxillofac Radiol. 2020;49(8):20190504. doi:10.1259/dmfr.20190504

10. Machtou P, West J, Ruddle CJ. Deep shape in endodontics: significance, rationale, and benefit. Dent Today. 2022;41(1):74–7.

11. Orth A, Ploschner M, Wilson ER, et al. Optical fiber bundles: Ultra-slim light field imaging probes. Sci Adv. 2019;5(4):eaav1555. doi:10.1126/sciadv.aav1555 

12. Lee CM, Engelbrecht CJ, Soper TD, et al. Scanning fiber endoscopy with highly flexible, 1 mm catheterscopes for wide-field, full-color imaging. J Biophotonics. 2010;3(5-6):385-407. doi:10.1002/jbio.200900087

13. Zeidan A, Do D, Kang D, et al. High-resolution, wide-field, forward-viewing spectrally encoded endoscope. Lasers Surg Med. 2019;51(9):808–14. doi:10.1002/lsm.23102 

14. Wen Z, Dong Z, Deng Q, et al. Single multimode fibre for in vivo light-field-encoded endoscopic imaging. Nat Photon. 2023;17:679–87. doi:10.1038/s41566-023-01240-x

15. Xie N, Tanguy QAA, Fröch JE, et al. Spectrally-encoded non-scanning imaging through a fiber. arXiv Phys. 2023. doi:10.48550/arXiv.2305.17113

16. West JD. The role of the microscope in 21st-century endodontics: visions of a new frontier. Dent Today. 2000;19(12):62–4, 66–9.  

17. van As GA. Digital documentation and the dental operating microscope. Oral Health. 2001;91(12):19-30. 

ABOUT THE AUTHOR

Dr. West received his DDS degree from the University of Washington, where he is an affiliate professor, and his MSD degree in endo-
dontics from Boston University, where he was honored with the Distinguished Alumni Award. Dr. West is founder and director of the West Center for Endodontics in Tacoma, Wash, where he is in private practice with his 2 sons, Jason and Jordan. He can be reached at (253) 473-0101 or via email at johnwest@centerforendodontics.com.

Disclosure: Dr. West is co-inventor of ProTaper and WaveOne and the inventor of JW17 Microexplorers and Micro Endo/Perio probes. He also serves on the clinical advisory board of Perimetrics, Inc.

NOTE ABOUT UPCOMING WEBINAR

Dr. John West will be leading a FREE CE webinar on March 27 at 1 PM (EST) that expands on the topic of this article.

In this FREE CE webinar, the esteemed Dr. John West will describe new and exciting endodontic technologies in combination with tools from the past and how these are used today in his everyday practice. Techniques and carefully documented protocols are shared in a fun and playful way.

Click HERE to register now.

Endodontic mastery at its essence comes down to achieving high-quality, reproducible results without reliance on a particular instrument system (matching instruments, motor presets, matching paper and gutta-percha points, etc). Rather, endodontic mastery is derived from reliance on basic principles that can be applied to virtually any system of instruments or materials. In practical terms, this means adherence to literature-based and time-proven concepts. This clinical article was written to provide the general dentist with a set of guiding endodontic principles that can be implemented using any shaping and obturation system for the types of root canal procedures that will be commonly treated by general dentists performing endodontic therapy.  

GUIDING PRINCIPLE 1: CASE SELECTION AND PREPARATION FOR TREATMENT

As a starting place, it is essential that the clinician perform a thorough endodontic examination and provide a pulpal and periapical diagnosis for every case prior to making access. This examination requires adequate radiographic assessment (possible CBCT and adequate diagnostic, 2D periapical radiographs); thermal testing as required; and assessment of percussion, palpation, mobility, and probings, all relative to controls.  

Accompanying the aforementioned diagnosis, the clinician should obtain written informed consent. Ideally, this consent requires that the procedure be reviewed personally with the patient, risks discussed, questions answered, and alternatives given. Coincident to obtaining a pulpal and periapical diagnosis, the clinician should assess the iatrogenic risks of treatment (file separation in severely curved and calcified canals, extrusion of irrigants and filling materials in lower second molar apices that lie near the mandibular canal, and perforation in calcified canals, among many potential sources of risk). Prior to starting the case, profound local anesthesia must be assured. The rubber dam is the legal and ethical standard of care. 

GUIDING PRINCIPLE 2: PREPARE AN ACCESS THAT PRESERVES TOOTH STRUCTURE AND PROVIDES VISUAL AND TACTILE CONTROL 

The astute clinician takes a CBCT scan as indicated (in the presence of complex anatomy, vital anatomic structures, severe curvature, possible resorption, retreatment cases, etc). The CBCT scan can inform the clinician of the location of canal orifices, given the preoperative measurement tools embedded in the software. Adequate 2D periapical images prior to treatment can also help the clinician mentally imagine orifice locations. Preservation of tooth structure in access and canal locations is accentuated by using safe-ended burs under a surgical operating microscope (SOM) (EndoGuard [Komet], EX-24 [Mani], and others). Safe-ended burs allow removal of tooth structure on axial walls without gouging the pulpal floor (Figure 1). 

Figure 1. EndoGuard (Komet). This safe-ended bur is used to plane axial access walls without gouging the pulp floor and unnecessarily removing tooth structure.

In relatively simple cases, opening into the chamber is straightforward. Severely calcified cases present challenges in canal location, providing an indication for CBCT. Attempting access into severely calcified pulp chambers and/or crowned teeth with obscured pulp chambers is highly problematic. Tipped and/or rotated teeth also present the clinician with perforation risk. Without significant experience and advanced visualization, ie, the SOM and CBCT, these teeth are best referred.  

It is axiomatic that the clinician attempts to save as much tooth structure as possible during access and canal preparation to minimize the long-term risk of crown and root fracture. Specifically, it is critical to preserve pericervical dentin (4 mm coronal and apical to crestal bone). Caries may ultimately dictate how much tooth structure is removed, but the ideal access should be made first and followed by careful caries removal (often with a slow-speed CA round bur of an appropriate diameter). The use of a caries indicator is helpful to ensure complete caries removal. Assurance of straight-line access is optimal prior to entering files into a canal orifice, shaping the coronal third, and/or taking length measurements. 

Canal location is generally straightforward in non-calcified cases, but in the daily practice of an endodontist, many non-vital cases are moderately to severely calcified, hence the need for specialty burs (EndoTracer [Komet], 1,500 to 20,000 rpm; 34-mm #2 CA burs [Mani]), which allow the clinician far greater precision in tooth structure removal during canal location relative to their short shank options (Figure 2). 

Figure 2. EndoTracer (Komet). These extended round burs are very help- ful in selectively removing tooth structure while attempting to locate calcified canals. Alternatively, ultrasonics would be another option for this purpose.

Alternatively, specialty ultrasonic units and tips can be used for this purpose. Ultrasonics are beyond the scope of this article, but if appropriate care is undertaken to avoid heat generation during their use, ultrasonics are a precise method for canal location in addition to exacting tooth structure removal. The Varios 970 (NSK) is the author’s preferred ultrasonic unit in combination with NSK tips. The unit features its own irrigant reservoirs, and the variation in power between the lowest and highest powers is notable. Alternative tips and units include those manufactured by Dentsply Sirona and Bonart, among many other manufacturers.  

GUIDING PRINCIPLE 3: REMOVE RESTRICTIVE DENTIN AT THE ORIFICE AND IN THE CORONAL THIRD BEFORE MOVING APICALLY 

Be it with the use of small Gates Glidden drills (#1 or #2) and/or NiTi orifice openers, opening the orifice, removing restrictive dentin, clearing the chamber, and providing clear and unmistakable orifices for file insertion has immense value. Orifice openers come in many forms, sizes, and tapers and include rotary, reciprocating, and Gates Glidden drill varieties. All of these have the same purpose, which is to define the orifice and provide files and irrigants unrestricted access to the more apical portions of the canal. Coincident with the steps above, it is critical to clear the chamber with sodium hypochlorite and water rinsing to avoid debris from apical movement. 

Endodontics is a sequential process. Profound local anesthesia precedes access. Conservative access and unroofing the pulp chamber precede canal entry. Shaping the coronal third and defining the orifice precedes placing instruments into the middle canal third. 

When shaping multi-rooted teeth, it’s immensely helpful (especially with novice clinicians) to do so sequentially because it aids in conceptualizing protocol. In practical terms, this means resisting the urge to place orifice openers and glidepath files into the apical third before the coronal third is shaped and irrigated. It is easy to lose track of where one is in the cleaning and shaping process if different files are taken to different canal levels in multirooted teeth simultaneously. Lack of flowing taper and canal transportation can easily result if the clinician loses sight of where he or she is in the preparation process and/or does not have a clear vision of the final desired shape. 

GUIDING PRINCIPLE 4: NEGOTIATE THE CANAL TO THE APEX AND OBTAIN A TRUE WORKING LENGTH 

Canal negotiation with hand files informs the clinician of the true calcification, curvature, apex size, 3D nature of the apex and canal, canal length, and exact position of the minor constriction. It is the authors’ preference to always precurve hand files and always start canal negotiation with a #6 hand K-file. In addition, hand files are inserted into a canal once and then discarded as they rapidly lose their sharpness. Hand files come in a bewildering array of cross-sectional designs, materials, and clinical attributes. As a result, making generic recommendations about which hand files to use for a specific clinical indication is challenging due to the ability to achieve a particular task with many different hand files. This said, for the vast majority of canals, the standard K-file (.02 tapered hand K-File [Komet], K-Files [Mani]) will provide the average general practitioner the ability to negotiate canals, prepare a glide path, and obtain a true working length with an apex locator (Root ZX [J. Morita], EndoPilot [Komet], ProMark [Dentsply Sirona], and more). 

The above notwithstanding, the single greatest variety of hand files (designs, lengths, tapers) available commercially is represented by the line of instruments marketed by Mani Dental of Japan. The clinician is directed to Mani’s catalog of safe-ended hand files, stiff hand files for canal negotiation in calcified cases (D Finders), and tapered hand files, among many other hand file options.  

Once precurved, in the presence of irrigant, the hand file should slide to the estimated working length, and the apex locator should read 0.0 (the position of the minor constriction), which is the most natural place to end shaping, irrigation, and obturation procedures. More specifically, instrumentation, irrigation, and obturation should end at the exit of the canal from the tooth with careful attention paid to the avoidance of extrusion of foreign materials beyond the constriction. Apex locator measurements are most accurately made in a dry canal (despite the manufacturer’s assurances to the contrary) with the largest file possible, taking care not to touch the file to metal during measurement. 

GUIDING PRINCIPLE 5: CREATE THE GLIDE PATH

Glide paths can be created with K-files, with rotary NiTi instruments, and through the reciprocation of hand K-files, among other methods. Common glidepath instruments include PathGlider for FQ (Komet), PathGlider for ProcQ (Komet), ProGlider (Dentsply Sirona), and PathFile (Dentsply Sirona), among many others. A properly created glide path significantly reduces the possibility of NiTi file breakage and ensures a time savings in that shaping files should move easily to the true working length. The glide path should be made to the true working length with frequent recapitulation using hand K-files to ensure that the canal path remains open and negotiable. Recapitulation should be accompanied by frequent irrigation and canal flushing to maximize debris removal, allowing the master cone to fit to true working length. 

Should a canal become non-negotiable where it was once negotiable, in all likelihood, either a ledge has begun or the canal is blocked with debris. Rather than forcing additional files apically, the clinician should stop, go back to smaller precurved hand files, and attempt to regain the canal path and/or irrigate the debris coronally. File separation, canal transportation, and a wide variety of iatrogenic events have as their origin an impatience to reach the apex, especially in the presence of a blockage. The use of a viscous EDTA gel, such as ProLube (Dentsply Sirona) or File-Eze (Ultradent Products), may be valuable in bypassing a ledge or negotiating around debris and facilitating removal. 

Once a #15 hand file can spin freely at the TWL, the glide path is prepared, and the canal is ready for shaping. Many mechanized glidepath instruments are .03/15 in dimension. Once they are taken to the TWL, the glide path is prepared.  

GUIDING PRINCIPLE 6: SHAPE AND DISINFECT THE CANAL

Given the steps taken above, if performed correctly, shaping should be a formality. The shaping file utilized should move to the apex with minimal pressure in the presence of an adequate glide path. Knowing the endpoint of shaping and the desired goal of irrigation provides strong clues as to when the clinician is done and the canal is ready for obturation. 

Ideally, the canal is prepared when the canal can be adequately disinfected and obturated. The advent of laser disinfection (Waterlase [BIOLASE], LightWalker [Fotona]) and multisonic negative/neutral pressure systems (GentleWave [Sonendo]) have all allowed the disinfection of smaller prepared canal spaces relative to traditional methods (passive ultrasonic irrigation, sonic irrigation, mechanical agitation, negative pressure systems [EndoVac]). While an absolute superiority of any given irrigation method has not been shown in the literature, and no single regimen or system has been able to demonstrate absolute sterility in canals, it is fair to say that we are closer to this objective than ever before. 

In the context of shaping, if irrigation is ideal and adequate with regard to volume, placement, activation, refreshment, and solution type, it is clear that irrigation is performing the disinfection step in the endodontic procedure and that removal of tooth structure is of secondary value in cleaning. Stated differently, removal of tooth structure allows for irrigants to enter canal spaces and perform removal of the smear layer, dissolution of tissue, and/or antibacterial functions. Traditional irrigation solutions have included sodium hypochlorite, 17% EDTA, and 2% chlorhexidine. Newer “2-in-1” irrigation solutions have emerged in the marketplace, such as Triton (Brasseler USA), which are stated to disinfect canals while simultaneously removing the smear layer.  

Methods to shape the canal generally fall into 2 categories: rotary- and reciprocation-powered NiTi files. There are dozens of commercially available NiTi systems. The cases shown were prepared with both the Procodile Q heat-treated system (reciprocation) or the FQ system (rotary), both powered by the EndoPilot motor (Komet). One significant advantage of the EndoPilot motor relative to others is the optional setting for user control of forward and backward degrees of reciprocation. The unit also features a heat source and an apex locator built in, and added features include a gutta-percha extruder and ultrasonic capability (Figures 3 and 4). 

Figure 3. (a to e) Cases shaped using either the Procodile Q heat treated system (reciprocation) or the FQ system (rotary), both by powered by the EndoPilot motor (Komet). (f) Procodile Q (Komet).

Figure 4. The ProMark endodontic motor (Dentsply Sirona) reciprocates and provides a rotary function with presets. The forward degree and reverse degrees of reciprocation cannot be user-modified as they can on the EndoPilot motor. ProMark motors typically are used with the WaveOne reciprocating system (Dentsply Sirona).

Figure 5. Dia-Root Bio Sealer (DiaDent) is a calcium silicate-based bioceramic sealer in the same general class as BioSeal (Komet) and EndoSequence BC Sealer (Brasseler USA).

In summary, preparing a canal space with narrowing cross-sectional diameters requires respecting the unique anatomy of the tooth. Maintaining the canal’s initial position, keeping the minor constriction at its original position and size, and appropriately sizing/preparing a canal space that can be predictably irrigated and obturated are the goals of canal shaping, regardless of the system used. In guitar terms, some players like Fender, some players like Gibson, and there is a universe of players who like other models. Which system is best is a matter of personal preference. What is critical is that the clinician knows his or her system, its attributes and limitations, and how to use it comprehensively from orifice to apex. 

GUIDING PRINCIPLE 7: OBTURATION 

Once the chosen irrigation/disinfection protocol has been achieved, the clinician should be able to dry the canal with paper points, fit a cone with a modest amount of sealer on it (ideally a calcium silicate sealer, such as BioSeal [Komet] or Dia-Root Bio Sealer [DiaDent], among many), and take a trial cone radiograph to assure that the master cone is in the correct position relative to the apex before obturation is concluded. All of the major instrumentation systems available at this time have matching paper points and gutta-percha points, whereby the master apical file (the largest file used at the apex) has a matching paper point and gutta-percha point. The cases illustrated using both Procodile Q and FQ (Komet) were obturated with this convenience (Figure 5). 

It is beyond the scope of this article to discuss obturation. This stated, if the clinician is going to perform endodontics, it is essential to have a heat source and a source of extruded gutta-percha readily at hand. Reliable systems with these features include the Dia-Duo (DiaDent), Calamus Unit (Dentsply Sirona), and the optional attachments to the EndoPilot (Figures 6 and 7). 

Figure 6. (a) Dia-Duo (DiaDent) is a cost-effective heat source with a smaller footprint relative to some other market options and a gutta-percha extrusion option. (b) The Calamus Unit (Dentsply Sirona) is a proven alternative to the Dia-Duo, but with a slightly larger footprint.

Figure 7. The EndoPilot motor has expanded capabilities to provide a heat source, an apex locator, gutta-percha obturation, and ultrasonics.

SUMMARY

This article has provided the reader a road map of steps on the road to endodontic mastery. Guiding principles that are independent of the material used have been presented. These principles include the critical importance of irrigation, removal of restrictive dentin in the coronal third, and achieving apical patency, among other key concepts. We welcome your feedback.

ABOUT THE AUTHORS

Dr. Neal earned his DMD degree from Roseman Dental School in 2023 and currently attends the GPR at Ohio State University. He can be reached at tylerhneal@gmail.com. 

Dr. Mounce earned his DDS degree from Northwestern Dental School and received his endodontics certificate from Oregon Health Sciences University. He practices endodontics in Eagle River, Alaska. He is widely published in trade magazines and has lectured globally. He can be reached via email at
richardmounce@mounceendo.com. 

Disclosure: The authors report no disclosures. 

Do you ever stop to reflect that, as dentists, we are living in a truly amazing time? We have incredible technology at our fingertips, and patients are fortunate to have unprecedented access to dental care.

But no matter how much shiny, state-of-the-art technology is available, if dentists believe that a tooth can’t be saved, it automatically becomes impossible to save it. We were all taught to cultivate certain beliefs in dental school. However, have you ever thought, “I wonder if that tooth would respond to treatment?” Remembering your training, though, you decided the safest bet was to extract.

Over the years as a practicing endodontist, I’ve been privileged to witness so many “unsavable” teeth be saved that I knew I had to re-examine my own beliefs.

Today, I view myself as a tooth saver, and I’d like to encourage all of us to open ourselves up to new beliefs about which teeth can be saved. This way, we can serve our patients at an even higher level.

Teeth are so incredibly important, but since we treat them day in and day out, we sometimes lose sight of the bigger picture.

What if our beliefs were the most important piece of technology that we really needed to upgrade? Take a moment, step back, and think about it. I view our teeth as tiny little temples within our mouths—the gateway to our bodies. Our teeth help nourish and hydrate our bodies, and they give us confidence when we smile. Teeth are precious, and we were born with them for many reasons.

Right now, I believe we are being called to make a shift in our beliefs around saving vs extracting these precious pearls that Mother Nature gave each of us. That way, we can wholeheartedly help our patients.

We can each trust ourselves to save teeth, and we can trust the incredible power of the human body to heal when given proper treatment. Believe in your healing power as a dentist. 

I’m not asking you to shift your beliefs without evidence, though. So I’m going to use real tooth stories from my own practice to explore some of the biggest and most common dental beliefs about “unsavable” teeth. Once we shift these beliefs into the new, upgraded beliefs I will propose, we can make a long-lasting, positive impact on the patients we touch. Walk with me down Tooth Story Lane, and I hope you will feel inspired, empowered, and ready to make an upgrade to your beliefs.

COMMON BELIEF NO. 1: BIG LESIONS DON’T HEAL 

How do you feel when you encounter a big lesion? If you’re thinking, “It’s hopeless; let’s extract it,” you aren’t alone, my friend. Across the community of dental professionals, there are different views on whether these teeth should be extracted or saved.

It’s easy to be concerned about the amount of bone loss around the tooth. The general teaching in dentistry is that the tooth will not respond to treatment, especially when there is a loss of the buccal cortical plate. In this situation, it’s not uncommon for us, as dentists, to believe the treatment won’t work.

But there is a shining beacon of hope. We can actually see healing in this scenario when we shift our thinking. 

Understanding the pulpal diagnosis of the tooth—and furthermore, understanding the fact that when a patient has a necrotic pulp, it will create bone loss—is an essential part of this discussion.

Sometimes that bone loss is little, and sometimes it’s monstrously big. It will vary per case and per patient, so I encourage us not to be so quick to judge these situations with a blanket statement. If we solely look at the radiograph and treat it based on the size of that lesion without doing any endodontic diagnostic testing, we are making a diagnosis based on the limiting beliefs that have been imprinted on so many of us from our previous teachers. And that means that, despite our very best intentions and aspirations, we may be doing our patients a disservice.

It’s time to truly understand the disease process and step into our superhero roles as dentists to save teeth.  

A Tooth Story About a Giant Periapical Radiolucency

Take, for example, a 46-year-old woman who presented to my office after her dentist found a periapical radiolucency around tooth No. 31. She was asymptomatic, and there was a significant amount of circumferential bone loss.

I performed my endodontic diagnostic tests and found that the tooth had no response to cold, had no pain upon percussion, and had no mobility, believe it or not. Additionally, there was a 9-mm mid-buccal probing (all other areas of the tooth probed normally). I diagnosed the tooth as necrotic pulp and chronic apical abscess on No. 31 (Figures 1a and 1b).

Figure 1a. Preoperative periapical radiograph of tooth No. 31.

Figure 1b. Pre-op bite-wing radiograph of tooth No. 31.

Most of the time, when I present this case in my lectures, I ask the audience, “What would your treatment plan be?” The answer I most often get is “Extraction.” This is because we, as dentists, have been taught to believe that lesions of this size are incapable of healing.

Instead, what’s important to understand is that the endodontic diagnosis (not lesion size) is what will guide you to the right treatment plan.

Remember, necrotic pulps create bone loss, and sometimes that bone loss can be massive. That just happens to be what is natural for that particular patient, including the one I’m sharing with you here.

As an endodontist, I have learned to reframe the beliefs that I learned in dental school and to trust my diagnosis. So, in this case, I did the root canal (Figure 1c).

Figure 1c. Immediate final post-operative obturation radiograph of tooth No. 31.

Now, it’s just a matter of giving the body the time that it needs to regenerate that bone. This is the importance of following up with your patients when it comes to endodontics. One year later, I witnessed her great recovery. Some may call it a miracle, but it’s not. It’s simply the superpower that exists within all of us: the ability to regrow our own bone back (Figure 1d).

Figure 1d. One-year recall radiograph of tooth No. 31.

And at 2 years postoperatively, there was even more bone deposition and maturation (Figure 1e). 

Figure 1e. Two-year recall radiograph of tooth No. 31.

All of this occurred with root canal therapy only. There was no other dental intervention.  

This is not a one-off success story. It can happen time and time again in any practice—so long as we relax into what our bodies are capable of, like regrowing bone, given enough time and healing.

In sharing this case, I intend for us to understand and trust our diagnosis to save teeth. When we understand the etiology of the disease process, we can make a more effective and meaningful treatment plan that we can be confident will serve our patients.

But if we were taught that big lesions don’t heal, and we impose that belief on our patients, it may lead them in the wrong direction. So many other dentists would have extracted this tooth. 

I believe that when we, the providers, can reframe our dental beliefs to trust that lesions can heal with endodontic treatment—no matter their size—we can serve our patients to the fullest extent possible.

Tooth-saving belief No. 1: Lesions can heal with endodontic treatment, no matter their size.

COMMON BELIEF NO. 2: THE J-SHAPED RADIOLUCENCY MEANS THE TOOTH IS FRACTURED

The J-shaped radiolucency most certainly gets a bad reputation when making an endodontic diagnosis. And despite having more than a decade of endodontic experience as a specialist, it still makes me second-guess my own diagnoses when I see them.

However, we now know and accept that the human body will look for the pathway of least resistance to drain an infection, and this may just happen to look like a J-shaped radiolucency, meaning that the tooth is not cracked at all.

If there is one thing I could change about endodontic education within dental school, it would be to emphasize the fact that J-shaped radiolucencies are not synonymous with root fractures. 

If you are questioning the probing on the mid-buccal because you, like me, were taught that a probing equates to a root fracture—and, therefore, a non-restorable tooth—I want to address your concern. It is also not true that an area that probes is always associated with a root fracture. A probing can simply mean that the body found the pathway of least resistance to drain the infection and created a sinus tract (hence the diagnosis of a chronic apical abscess). 

This sinus tract can drain through the sulcus and does not need to look like a pimple on the gingiva. Unfortunately, this sinus tract clinically looks just like a probing that is associated with a root fracture, so it most definitely complicates the endodontic diagnosis and creates a layer of uncertainty.

Let’s explore an example to illustrate this point.

A J-Shaped Radiolucency Tooth Story

A 38-year-old woman had a previous root canal that appeared to be failing. When I looked at her preoperative radiographs, I could see that notorious J-shaped radiolucency around the mesial root and even some bone loss around the distal root (Figures 2a and 2b).

Figure 2a. Pre-op periapical radiograph of tooth No. 30.

Figure 2b. Pre-op bite-wing radiograph of tooth No. 30.

My diagnostic tests showed that there was some moderate tenderness to percussion and obviously no response to cold. All other findings were within normal limits, except that there was a 9-mm mid-buccal probing. The diagnosis was a previously treated and chronic apical abscess on No. 30.

I also obtained a pre-op cone beam, which more clearly delineated the classic J-shaped radiolucency (Figures 2c to 2f).

Figure 2c. Pre-op sagittal CBCT view of tooth No. 30.

Figure 2d. Pre-op axial CBCT view of tooth No. 30.

Figure 2e. Pre-op coronal CBCT view of the mesial root of tooth No. 30.

Figure 2f. Pre-op coronal CBCT view of the distal root of tooth No. 30.

I had a long discussion with the patient to present all of her treatment options, including endodontic re-treatment vs extraction. This is because I always want to empower my patients with knowledge so that they can make the best choices for their health.

We decided together that we both felt comfortable attempting the re-treatment to see if we could save the tooth. I told her that if I located an internal fracture under magnification, I would have to refer her for the extraction. 

The patient, however, wanted to do whatever it took to save her tooth, which meant giving treatment a try. I was on board with this plan because, over the years, giving teeth a chance has allowed me to see what magic our bodies are truly capable of.

Upon removing the gutta-percha and carefully inspecting the internal walls of the tooth, I didn’t see any sign of a fracture, so I continued to obturate the tooth (Figures 2g and 2h).  

Figure 2g. Immediate post-op radiograph of tooth No. 30.

Figure 2h. Immediate post-op off-angle radiograph of tooth No. 30.

As stated earlier, followup is the key to understanding the healing process in endodontics. I saw her back in my chair at her one-year post-op. She had almost completely regenerated all of her bone (Figure 2i).  

Figure 2i. One-year recall radiograph.

This patient does have a bit more healing to do, but this will continue to happen with more time. She has made remarkable progress for a lesion of this size, which extended into the furcal area. All that means is that it may take a bit longer to heal. Bone is slow to grow, so when you see a lesion of this magnitude and shape, it may take a few years to fully reconstitute with bone. “Bone can grow” is another empowering belief that I encourage each of us to embody in our practices in order to fully serve our patients.

Tooth-saving belief No. 2: J-shaped radiolucencies may be restorable.

COMMON BELIEF NO. 3: WHEN A CANAL CAN’T BE SEEN ON a CBCT, IT MEANS IT’S NOT THERE 

It is generally accepted that the MB2 canal of a maxillary first molar is one of the hardest canals to find and treat in the world of endodontics. Cone-beam technology has no doubt been a game-changer for me with respect to this canal. But it can also be a trap if we are not prepared to read the scans correctly.

Finding the proper support in reading these scans can also be a challenge after we have invested in CBCT technology, so I want to share a few secrets that I have learned, hoping you will have an easier time succeeding.

An MB2 Canal Tooth Story

This 42-year-old male patient was in need of a root canal due to a high level of pain. His pre-op radiographs showed a deep composite restoration on tooth No. 2 (Figures 3a and 3b). His endodontic diagnostic tests revealed that he had lingering pain to cold and tenderness to percussion. All other testing was within normal limits. I diagnosed tooth No. 2 with symptomatic irreversible pulpitis and symptomatic apical periodontitis.

Figure 3a. Pre-op periapical radiograph of tooth No. 2.

Figure 3b. Pre-op bite-wing radiograph of tooth No. 2.

Before I start any root canal, I always like to understand the internal canal anatomy of a tooth prior to the procedure. Therefore, I took a cone-beam scan (Figures 3c to 3e).  

Figure 3c. Pre-op sagittal CBCT view of tooth No. 2.

Figure 3d. Pre-op axial CBCT view of tooth No. 2.

Figure 3e. Pre-op coronal CBCT view of tooth No. 2.

The axial view of the CBCT scan is where a dentist could easily get stumped (Figure 3d). When looking at tooth No. 2, it appears as if there are only 3 canals: the MB, DB, and  P canals. However, when we look at the connecting root of the MB canal to the P canal, there is definitely more space that could house a teeny, tiny canal—even though you can’t actually see a fourth canal on the scan.  

It is really important to look at your cone-beam scan in all of its planes. In these situations, I particularly like to look at the tooth in the coronal view (Figure 3e).

Imagine a line going through the MB orifice and the P orifice (from the axial slice). This creates the coronal slice that you are seeing (Figure 3e). And now we can see that there is an MB2 canal that could not be seen as clearly in the axial view (Figure 3d). 

What did this tell me about this case, even before I accessed the tooth? It told me that this MB2 was going to be a tough one to find.

If we look at the axial view alone, it would be so easy to believe that there is no MB2 at all in this case. Unfortunately, that would have resulted in a root canal failure in the future, which neither the dentist nor the patient would want to happen! That’s why the thought that canals that can’t be seen on a CBCT scan simply aren’t there is ultimately a false belief that each of us needs to examine.

Remember the 2 cardinal rules of root canals: Root canals only work when we (1) find all the canals and (2) get to the end of every canal.

As a side note, this may be a great way to perform a risk assessment and see if this is a case that you want to take on in your practice or refer to a specialist. In my opinion, this type of canal configuration is one of the hardest to treat.

I am incredibly grateful that, thanks to my CBCT scanner, I can understand the difficulty level of the canal’s anatomy before I even get inside. This allows me to have a more meaningful conversation with my patients, and it also manages their expectations throughout the process of their treatment. 

With all of this additional information and guidance from my cone-beam scan, I was able to take this case to completion with confidence that I was addressing the entire tooth (Figures 3f to 3h). 

Figure 3f. Conefit radiograph of tooth No. 2.

Figure 3g. Backfill radiograph of tooth No. 2.

Figure 3h. Immediate post-op radiograph of tooth No. 2.

I hope that we’ll collectively adopt a new empowering belief that can lead to saved teeth: that the MB2 canal is almost always there, even if it isn’t easy to see. It’s better to assume it is than to risk a failed root canal and re-treatment.

Tooth-saving belief No. 3: The MB2 canal is almost always there, even if it isn’t easy to see.

COMMON BELIEF NO. 4: WHEN A TOOTH IS STILL SYMPTOMATIC AFTER ROOT CANAL THERAPY, THE TOOTH MUST BE CRACKED 

One of the most frustrating aspects of being an endodontist is when you complete a picture-perfect root canal and that tooth still bothers the patient afterward. It doesn’t happen very often, but when it does, it can feel so defeating. 

The uncertainty as to why that tooth is still giving our patients some pain can be frustrating. The typical explanation I have heard dentists give patients is that the tooth is cracked and now needs to be extracted.

But if we really think about it, this determination doesn’t ultimately serve our patients. Most of the time in these scenarios, the tooth is not cracked, but rather there is still some bacterial contamination in the tooth. So, my recommendation is to re-treat the root canal before we condemn the tooth. Consider this—would you extract your own tooth or your child’s tooth, or would you give it another chance?

This same clinical scenario has happened to me in my own practice, and my first instinct is to redo my own work. When the patient still feels something when he or she taps on that tooth, I always offer to try again to see if re-disinfecting the tooth’s canals helps the patient. Happily, it works about 80% of the time and the patient feels better.

The key is not to give up on your patient’s tooth when it’s savable. It’s totally okay to try again. Re-treating my own root canals has taught me many lessons, has changed my tooth beliefs permanently through years of evidence, and has made me a better clinician. I now understand root canal anatomy better than ever before, and I appreciate that the internal anatomy can really limit what we can do with traditional root canal therapy.

This has encouraged me to invest in additional technology, such as the GentleWave System (Sonendo), which can elevate my current root canal experiences and outcomes. 

Examples of Root Canal Re-treatment Success Stories

Figure 4 shows a few post-op radiographs of tooth stories that demonstrate what I mean about root canal anatomy.

Figure 4a. Post-op radiograph of tooth No. 21 (the smaller canal was not instru- mented with a rotary file, only activated irrigation via the GentleWave System [Sonendo]).

Figure 4b. Immediate post-op radiograph of tooth No. 15 (the smaller MB2 canal was not instrumented with a rotary file, only activated irrigation via the GentleWave System).

Figure 4c. Immediate post-op radiograph of tooth No. 19 (the smaller middle mesial canal was not instrumented with a rotary file, only activated irrigation via the GentleWave System).

These teeny tiny canals are areas where no rotary file can go—and they didn’t in these cases—which makes mechanical instrumentation difficult.

I treated all of these cases with GentleWave technology. This has solidified my belief that irrigation is instrumentation, and that makes it a crucial part of the endodontic future. It’s a huge paradigm shift, and it’s time to believe in it.

So, when we are in this situation, remember the new belief that teeth that are symptomatic after a root canal may not be cracked but just need re-treatment. That is because there could be a tiny canal somewhere that is still harboring a little bit of bacteria. 

It’s okay if you don’t have the same technology at your disposal, but my purpose is to bring awareness into your life so you know where to turn to take the next step to help your patients. Maybe this means you treat the tooth, or maybe this means you refer to a specialist with that technology for re-treatment before you extract the tooth. Remember, it’s all about saving the tooth, and that only happens if we give it a chance.

Tooth-saving belief No. 4: Symptomatic teeth after root canals may not be cracked and may need re-treatment.

OLD BELIEFS GIVE WAY TO NEW, EMPOWERING, TOOTH-SAVING BELIEFS

My intention with these tooth stories has been to bring all of us hope that we can save more teeth and to inspire us to think and evaluate carefully before we extract. 

I encourage us to think twice before taking a tooth out and to embrace my motto in life, which is #GiveTeethAChance. 

When we do, we’ll find that:

• “Big lesions don’t heal” becomes “lesion size is not a determinant of healing ability.”
• “The J-shaped radiolucency means the tooth is fractured and needs to be extracted” becomes “the J-shaped radiolucency is not synonymous with a root fracture.”
• “A probing equates to a root fracture and, therefore, a non-restorable tooth” becomes “a probing can simply mean that the body has found the pathway of least resistance, and that tooth can be saved.”
• “Bone doesn’t grow back” becomes “bone can regrow, but it is slow, so have patience.”
• “When a canal can’t be seen on a CBCT scan, it’s not there” becomes “look at your cone-beam scan in all of its planes, and assume that the MB2 is almost always there.”
• “When a tooth is still symptomatic after root canal therapy, it must be cracked” becomes “when a tooth is still symptomatic after root canal therapy, some of the infection may have been missed, and a re-treatment will lead to a good outcome.”

These are not the only situations where teeth that are typically extracted can be saved. I’ve shared specific situations because they’re very common and because I also want us to start seeing a pattern. If there’s one message I hope dentists take away from this article, it’s this final tooth-saving belief: You are a tooth saver and a tooth healer if you allow yourself to be. You have the ability to save teeth, even in scenarios in which you didn’t think it was possible. It only requires your belief.

I hope you are feeling excited and that you are already starting to believe in the ability of teeth to be saved. Most of all, I hope you are ready to take on the identity of a tooth saver.

I promise that the more we start to cultivate these new, empowering, tooth-saving beliefs and truly understand the power of our human bodies to heal, the more we can create better outcomes that lead to better lives for patients around the world.

ABOUT THE AUTHOR  

Dr. Chopra is a board-certified endodontist, TEDx speaker, Forbes contributor, author, endodontic instructor, and founder of Ballantyne Endodontics in Charlotte, NC. Through her award-winning endodontic CE course, E-School, she teaches tangible lessons to make root canals simple. She can be reached at soniachopradds.com or soniachopradds.com/e-school, or via the Instagram handle
@soniachopradds.

Disclosure: Dr. Chopra is a KOL for Sonendo. She did not receive compensation for writing this article.  

Dr. Reeh graduated with a bachelor of science in chemistry with a minor in business from the University of Calgary in Alberta, Canada. He earned a doctor of dental surgery from the University of Alberta’s School of Surgery from the University of Alberta’s School of Dentistry and completed specialty training in endodontics at the University of Minnesota.

Ernest S. Reeh

Dr. Reeh obtained a master of science in material science and graduated with a doctor of philosophy in biophysics with a minor in engineering the University of Minnesota.

Dr. Reeh is the owner, doctor, and dentist at River Valley Endodontics since 1987. He is also a consultant for the 3M Dental Division and Carestream Dental and holds two patents for dental technology, which he earned in 1995. The doctor has also served as a volunteer researcher at the University of Minnesota and has been a lecturer both domestically and internationally in his field.

Dr. Reeh is a board-certified endodontist by the American Board of Endodontics and a fellow of the American Association of Endodontists.

Dr. Reeh has been in his current position for 35 years as a licensed dentist in the state of Minnesota.

His findings have been published in numerous professional journals, case reports and abstracts. He was also named Top Dentist in St. Paul Magazine.

The doctor would like to dedicate this honor with special thanks to his father, Robert E. Reeh, as well as Harold Messer Dentist, PhD, and William Douglas Dentist PhD.

For more information, please email Dr. Reeh at reeh@usfamily.net.

It has been well-documented that the “triad” for success in endodontics includes instrumentation, irrigation, and obturation. Without proper instrumentation, effective irrigation and obturation become nearly impossible, as it is the instrumentation that facilitates adequate disinfection and then obturation. A delicate balance must be struck when instrumenting a canal. On the one hand, we must create sufficient space in the canal to accommodate irrigants and medicaments for proper disinfection. On the other hand, we must preserve radicular dentin to maintain the tooth’s structural integrity and its resistance to future fracturing. The goal of endodontics is not only to eliminate infection but also to ensure the tooth survives long-term. Proper instrumentation is essential in achieving these goals.

There has clearly been a revolution in the realm of instrumentation. The time is gone when one might spend countless visits hand instrumenting a root canal. Today, we have the most efficient systems, utilizing nickel titanium (NiTi) rotary files that allow for a relatively quick and seamless canal preparation compared to instrumentation with stainless steel hand files.¹ As the saying goes, “with great power comes great responsibility,” and instrumentation with NiTi rotary systems is no exception. The dreaded file separation is something that anyone who has ever performed root canal therapy has experienced. The question is not how to deal with file separation but rather how to avoid it in the first place. 

NiTi is a “superelastic” metallic alloy that, when flexed, undergoes an austenitic-martensitic transformation from its original structure, making it extremely flexible.^2-5 This transformation usually happens when the metal is stressed, such as during the instrumentation of the root canal. If, however, the NiTi file is stressed beyond its elastic limit, it will break. One of the unique characteristics of NiTi is its “shape memory,” allowing it to be deformed during usage and then return to its original shape if it is not stressed beyond its elastic envelope.⁵ NiTi files also have high elastic flexibility in bending and torsion compared to stainless steel files. Flexibility is the hallmark of NiTi rotary files, and it is this feature that allows it to overcome one of the greatest challenges of root canal instrumentation, namely following the sharp and unexpected curves contained in most canals without causing iatrogenic damage, such as canal transportation—in essence, “respecting” canal anatomy (RCA) (Figures 1 and 2). Unfortunately, stainless steel files, in larger sizes, do not provide this same benefit. It is often forgotten that most canals have some curvature, whether in the mesiodistal dimension (noted radiographically) or buccolingually (not seen in 2D radiographs).⁶ When NiTi rotary files are used correctly, they are significantly faster and more efficient than stainless steel hand files.^7-10 

Figure 1. Altered apical anatomy: canal anatomy was not maintained due to increased dentin removal at the outer aspect of the curve caused by stiff files that often seek to return to their original shapes.

Figure 2. Cases that demonstrate “respecting root anatomy” via consistently maintaining canal curvatures.

Another unique feature of NiTi files is their tip design. When we think of a file, we think of an instrument that cuts along its entire length. Not so with most NiTi files, which have non-cutting tips that guide the instrument to the apical portion of the root canal. There is ample evidence that this feature makes NiTi superior in maintaining the original canal curvature, preserving the apical constriction, and avoiding canal transportation.¹¹ When instrumenting a canal, one of 2 things will likely happen: You will accommodate the canal by following its complex and tortuous anatomy, or the canal will accommodate you by straightening itself out to accommodate your aggressive instrumentation. The process of instrumenting a canal will only be a successful endeavor when one learns to accommodate the canal and not vice versa.

During root canal preparation, our goal is to maintain the original canal anatomy and to avoid iatrogenic canal transportation. What follows are some tips to help navigate calcified and curved canals while avoiding the unfortunate file separation and/or iatrogenic damage to root structure. Avoiding these errors and “respecting” apical anatomy will lead to greater outcomes in our endodontic treatment.

TIP NO. 1: HAND FILES FIRST!

There was a time when instrumenting a canal was accomplished completely with hand files, which could take many visits. The pendulum has swung, and now with NiTi rotary instrumentation, endodontic treatment can be carried out more seamlessly in less time. There is the misconception, however, that rotary files have replaced hand files completely. This couldn’t be further from the truth. Many practitioners will try incorrectly to jump straight to rotary. It is important to remember that without first obtaining a smooth glide path to the apex with hand files, rotaries will be stressed beyond their elastic limits, leading to needless file separations. Hand filing a canal, as opposed to rotary instrumentation, provides tactile sensation, which allows one to better gauge the level of curvature and calcification. As a general rule, rotary files should never be placed in a canal before the canal has been properly “scouted” with hand files. If you can’t get a hand file to length in a canal, rest assured that if you then try to force a rotary into that same canal, the chances of separation and/or transportation are high.  

TIP NO. 2: CORONAL FLARE

NiTi rotary instrument fractures can be greatly reduced by creating a proper coronal flare.^12-14 This allows the unobstructed penetration by the hand file and then later the rotary file all the way to the working length. This is done by preflaring the canal orifice with a NiTi orifice opener, which is placed only in the coronal third of the canal. Most rotary systems will contain an orifice opener (Figure 3a). The benefit of this file is its short length and wider taper. This is also one of the goals of the “crown-down” instrumentation technique. By removing coronal interferences and restrictive dentin from the coronal third of the canal, one will have a much easier time placing both hand files and rotary files into the canal and then down to length. The orifice opener eliminates the “triangle of dentin,” which obstructs the orifice (Figure 4). You may successfully leave this triangle of dentin and negotiate around it, but this puts tension on the file at the occlusal end, making it more likely to separate should it find additional tension when negotiating an apical curve. The ProTaper S1 file (Dentsply Sirona Endodontics) (Figure 3b) is another great favorite of many endodontists for flaring the coronal and middle thirds of the root canal.

Figure 3. (a) Orifice openers and (b) shaping file.

Figure 4. (a) “Triangle of dentin” obstructing entry into the root canal—the file is strained from navigating 2 curves instead of one. (b) The triangle of dentin is removed once the canal is coronally flared. (c) Unobstructed penetration of the file into the canal orifice and then the entire root canal system.

This file has the benefit of having a very narrow tip with a taper that allows for proper shaping of the coronal and middle thirds of the canal. It is prudent to remember that these rotary files should only be used after the canal has first been scouted with hand files. It is always important to stress moderation, as “over-flaring” a canal can weaken the tooth by removing too much dentin in critical zones, so while flaring is beneficial for many reasons, it should be done as conservatively as possible to avoid removing too much dentin, thereby weakening the root. The TruNatomy orifice opener (Dentsply Sirona Endodontics) (Figure 3a) is a great example of a file that appropriately flares the canal orifice without excessively removing dentin from the critical zones. One of the most important components for long-term tooth survival is maintaining as much dentin as possible, specifically pericervical dentin (PCD), which is the dentin near the alveolar crest (Figure 5). Preserving the dentin above and below the canal orifice/alveolar crest is crucial for long-term survival of the tooth.^15,16

TIP NO. 3: GLIDE PATH 

Another important component in proper instrumentation is establishing a glide path, which is the creation of a predictable path so that the rotary file can reach all the way to the working length unencumbered. The first step in creating this glide path is by hand filing the canal to at least a size  15 hand (K-) file. Although it is possible to skip the size 15 in loose canals, a tight canal will not accept a rotary file well before it has been opened to at least a size 15 K-file. Before one ever places a rotary file to length in a canal, he or she should first instrument the canal comfortably with an 8, a 10, and a 15 hand file to help remove the restrictive dentin and allow for a more predictable glide path. The orifice opener or ProTaper S1 can also help to establish this glide path. While most endodontists use K-files for hand instrumentation, a much stiffer C or C+ file can also help to loosen up a tight canal, as smaller size K-files will often buckle when encountering a tight canal. The use of these hand files will, in essence, pave the pathway for the first rotary instrument to length and reduce the chance of separation of the rotary files. Establishing the glide path also causes less canal transportation (“ledging”) as compared to preparations done without a glide path. To quote Dr. Cliff Ruddle, “Whoever owns the glide path wins the shaping game of endodontics.” 

TIP NO. 4: SEQUENCE MATTERS! 

Don’t skip around. If you start with a size 8 file, don’t skip to a size 15 as your next file in the canal. While this might be okay in a looser canal, developing healthy habits while instrumenting is important. It is tempting to cut corners, especially when hand filing a canal, as this can be quite tedious. This will place more stress on the larger size files and increase the odds of instrumentation errors, such as canal blockage and/or ledging (Figure 1). 

TIP NO. 5: RECAPITULATION

After each use of a rotary file, make sure to re-enter the canal with a smaller hand file. Rotary instrumentation creates a significant amount of debris, which can clog up the canal, negatively affecting the ever-important glide path. What occasionally happens is that, at some point during the instrumentation process, your file no longer reaches the working length. This is because either the canal has been ledged or, more commonly, dentinal debris has clogged a portion of the canal. Re-entering with smaller files throughout the instrumentation process to break up this debris allows for maintenance of the glide path. Putting a slight bend on the tip of the hand file can also help work around a blockage. Trying to penetrate this blockage with a rotary file will inevitably lead to file separation. Without the glide path, we end up stressing (pushing too hard on) the NiTi files, ultimately leading to fracture. 

TIP NO. 6: REUSE OF NICKEL TITANIUM FILES

How many times is too many? File fatigue will depend on several variables, including instrument properties, canal morphology, and operator skills.¹⁷ For example, working one calcified canal will stress a file more than working multiple “loose” canals. Forcing a file in a tight or curved canal will fatigue it more than placing a file in a relatively straight and loose canal. Thus, there is no magic number of times a file can be used. It is prudent to often examine the cutting edges for wear and strains. 

TIP NO. 7: ROTARY MOVEMENTS

Stopping the rotary file midway down a canal will put more pressure and stress on the file, predisposing it to fracturing because of cyclic fatigue. Constant movement of the rotary file within the canal will better distribute the forces and prevent breakage. The rotary file should be in motion as it is removed from the canal. Stopping the motor while the file is in the canal can potentially cause the file to get locked into a tight spot and separate.^18-25 A rotary file should be used in an “in-and-out” (pecking) motion with light apical pressure. Never force a rotary file into a canal, and never place heavy apical pressure as this will cause the file to lock into the canal and separate. When NiTi files fracture, it is due to cyclic fatigue or torsional strain. Torsional fracture is when the tip of the instrument locks in a canal while the shaft continues to rotate. Excessive force on the file during instrumentation causes the tip of the file to lock in a “tight spot.” Larger-sized files tend to be more resistant to these torsional fractures as they don’t bind as easily. Cyclic fatigue occurs after the repeated bending of instruments in curved canals, causing the metal to fatigue and fracture. Obviously, the more curved a canal is, the higher the probability of the file separating due to cyclic fatigue.

Figure 5. Preserving the dentin above and below the canal orifice/alveolar crest is crucial for long-term survival of the tooth.

TIP NO. 8: FILE INSPECTION

One of the indicators that a file has been fatigued and is on the cusp of breakage is when the flutes of that file begin to unwind. It should be a habit to always inspect the file for this unwinding, and when you see it, toss it (Figure 6). File inspection should also include wiping the file of debris before re-entering the canal. This can be done with wet cotton gauze. 

Figure 6. Note file deformation (unwinding of file flutes). This is an indicator that the file is on the cusp of breakage and should be discarded.

TIP NO. 9: IRRIGATION AND LUBRICATION  

Never file a dry canal as this will create excessive debris in the canal, which ultimately will lead to canal blockage. In trying to force your way through a blockage, the chances of file separation are significantly increased. Irrigation serves the purpose of disinfection and flushing of debris from the canal. Some commonly used lubricants/irrigants are RC prep (Premier Dental), EDTA, sodium hypochlorite, Triton (Brasseler USA), QMix (Dentsply Sirona), and MTAD.

TIP NO. 10: STRAIGHT-LINE ACCESS 

Straight-line access into the pulp chamber as well as the root canal is crucial to help avoid coronal tension on the file.²⁶ There are 2 components to straight-line access: the initial access into the pulp chamber and the access into the root canal. Managing both well puts less stress on the file and will ultimately prevent needless file separation. This also aids in glide path maintenance. It is prudent to point out that while straight-line access into both the pulp chamber and root canal is important, we must also strive to preserve as much dentin as possible to avoid weakening the tooth. Many have the motto “You can’t do what you can’t see,” but with more experience, skill, magnification, and image guidance, one can create smaller access preparations and still avoid iatrogenic damage while locating and treating all the complexities of the root canal system. The great benefit to conservative access is preserving the very valuable PCD (Figure 5). 

TIP NO. 11: BITE BLOCK

Having the patient use a bite block during treatment is another great way to avoid file separation. When the patient’s range of opening is compromised, your access to the posterior teeth may be limited. A sudden closure, even slight, by the patient during instrumentation can lead to file fracture. 

TIP NO. 12: PRE-BEND!

Obtaining access into a canal with hand or rotary files can be difficult, especially in an MB canal of a maxillary molar or a mesial canal of a lower molar. The angulation and location of the canal can make it challenging, especially with longer-length rotary files. A good piece of advice is to use shorter length files in these situations (21-mm length as opposed to 25-mm or 31-mm). One of the benefits of NiTi files is that they can be pre-bent to obtain the proper angulation. Putting a curve on the file can simplify this complexity (Figures 7a and 7b). Coronal flaring with shorter length files also helps obtain better access and prevents the dreaded “snap” of the file when it’s improperly placed in the canal. Pre-bending the tip of a small hand file also helps to navigate the curvatures within the canal itself and can help work around a blockage or ledge (Figure 7c).

Figure 7. Pre-bending the tip of a small hand file can help to navigate curvatures within the canal itself and help work around a blockage or ledge.

TIP NO. 13: BE PREPARED! 

Thoroughly inspect the radiograph before starting a case. CBCT can also help to evaluate subtle canal curvatures. Extra care in rotary file usage will be needed in cases that have calcified or curved roots. Never rush! Never blame the file! Never cut corners! With proper technique, patience, and experience, separating files will become a rare occurrence, and navigating curved and calcified canals will become less stressful and easier to manage.

ACKNOWLEDGMENTS

The author wishes to thank Drs. Charles Solomon, Leslie Elfenbein, and Eric Wachs for their valuable input and guidance.

REFERENCES

1. Short JA, Morgan LA, Baumgartner JC. A comparison of canal centering ability of four instrumentation techniques. J Endod. 1997;23(8):503–7. doi:10.1016/S0099-2399(97)80310-X 

2. Peters OA, Paque F. Current developments in rotary root canal instrument technology and clinical use: a review. Quintessence Int. 2010;41(6):479–88. 

3. Viana AC, Chaves Craveiro de Melo M, Guiomar de Azevedo Bahia M, et al. Relationship between flexibility and physical, chemical, and geometric characteristics of rotary nickel-titanium instruments. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;110(4):527–33. doi:10.1016/j.tripleo.2010.05.006

4. Peters OA, Gluskin AK, Weiss RA, et al. An in vitro assessment of the physical properties of novel Hyflex nickel-titanium rotary instruments. Int Endod J. 2012;45(11):1027–34. doi:10.1111/j.1365-2591.2012.02067.x

5. Shen Y, Zhou HM, Zheng YF, et al. Metallurgical characterization of controlled memory wire nickel-titanium rotary instruments. J Endod. 2011;37(11):1566–71. doi:10.1016/j.joen.2011.08.005 

6. Cunningham CJ, Senia ES. A three-dimensional study of canal curvatures in the mesial roots of mandibular molars. J Endod. 1992;18(6):294-300. doi:10.1016/s0099-2399(06)80957-x 

7. Kazemi RB, Stenman E, Spångberg LS. A comparison of stainless steel and nickel-titanium H-type instruments of identical design: torsional and bending tests. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000;90(4):500–6. doi:10.1067/moe.2000.108959

8. Schäfer E, Tepel J, Hoppe W. Properties of endodontic hand instruments used in rotary motion. Part 2. Instrumentation of curved canals. J Endod. 1995;21(10):493–7. doi:10.1016/s0099-2399(06)80519-4 

9. Tepel J, Schäfer E, Hoppe W. Properties of endodontic hand instruments used in rotary motion. Part 3. Resistance to bending and fracture. J Endod. 1997;23(3):141–5. doi:10.1016/S0099-2399(97)80262-2 

10. Tepel J, Schäfer E. Endodontic hand instruments: cutting efficiency, instrumentation of curved canals, bending and torsional properties. Endod Dent Traumatol. 1997;13(5):201-10. doi:10.1111/j.1600-9657.1997.tb00041.x

11. Kuhn WG, Carnes DL Jr, Clement DJ, et al. Effect of tip design of nickel-titanium and stainless steel files on root canal preparation. J Endod. 1997;23(12):735–8. doi:10.1016/S0099-2399(97)80345-7 

12. Hartmann RC, Peters OA, de Figueiredo JAP, et al. Association of manual or engine-driven glide path preparation with canal centring and apical transportation: a systematic review. Int Endod J. 2018;51(11):1239–52. doi:10.1111/iej.12943 

13. Kwak SW, Ha JH, Cheung GS, et al. Effect of the glide path establishment on the torque generation to the files during instrumentation: an in vitro measurement. J Endod. 2018;44(3):496-500. doi:10.1016/j.joen.2017.09.016 

14. Patiño PV, Biedma BM, Liébana CR, et al. The influence of a manual glide path on the separation rate of NiTi rotary instruments. J Endod. 2005;31(2):114–6. doi:10.1097/01.don.0000136209.28647.13 

15. Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010;54(2):249–73. doi:10.1016/j.cden.2010.01.001 

16. Clark D, Khademi JA. Case studies in modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010;54(2):275–89. doi:10.1016/j.cden.2010.01.003 

17. Yared G, Kulkarni GK. An in vitro study of the torsional properties of new and used rotary nickel-titanium files in plastic blocks. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003;96(4):466–71. doi:10.1016/s1079-2104(02)91706-3

18. Miyai K, Ebihara A, Hayashi Y, et al. Influence of phase transformation on the torsional and bending properties of nickel-titanium rotary endodontic instruments. Int Endod J. 2006;39(2):119–26. doi:10.1111/j.1365-2591.2006.01055.x 

19. Wolcott J, Himel VT. Torsional properties of nickel-titanium versus stainless steel endodontic files. J Endod. 1997;23(4):217–20. doi:10.1016/S0099-2399(97)80049-0 

20. Walia HM, Brantley WA, Gerstein H. An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod. 1988;14(7):346–51. doi:10.1016/s0099-2399(88)80196-1 

21. Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod. 2006;32(11):1031–43. doi:10.1016/j.joen.2006.06.008 

22. Plotino G, Grande NM, Cordaro M, et al. A review of cyclic fatigue testing of nickel-titanium rotary instruments. J Endod. 2009;35(11):1469–76. doi:10.1016/j.joen.2009.06.015 

23. Bergmans L, Van Cleynenbreugel J, Wevers M, et al. Mechanical root canal preparation with NiTi rotary instruments: rationale, performance and safety. Status report for the American Journal of Dentistry. Am J Dent. 2001;14(5):324–33.

24. Sattapan B, Nervo GJ, Palamara JE, et al. Defects in rotary nickel-titanium files after clinical use. J Endod. 2000;26(3):161–5. doi:10.1097/00004770-200003000-00008 

25. Pruett JP, Clement DJ, Carnes DL Jr. Cyclic fatigue testing of nickel-titanium endodontic instruments. J Endod. 1997;23(2):77-85. doi:10.1016/S0099-2399(97)80250-6 

26. Patel S, Rhodes J. A practical guide to endodontic access cavity preparation in molar teeth. Br Dent J. 2007;203(3):133–40. doi:10.1038/bdj.2007.682 

ABOUT THE AUTHOR

Dr. Stern is a Diplomate of the American Board of Endodontics. He is the director of endodontics at the Touro College of Dental Medicine and frequently lectures on the subject of clinical endodontics. He has lectured at many local county dental societies, at the New Jersey Dental Association Annual Session in May 2019, and at the Greater New York Dental Meeting in 2020. He maintains a private practice, Clifton Endodontics, in Clifton, NJ.

He can be reached at jstern5819@gmail.com or via the Instagram handle @the_barbed_broach1.

Disclosure: Dr. Stern reports no disclosures.  

In the early 1990s, the use of nickel-titanium (NiTi) alloy to manufacture engine-driven instruments for shaping root canals moved endodontics to a different level. Practitioners, universities, and companies started unprecedented cooperation to understand the countless advantages that adopting this unique metal alloy could provide for the evolution of the instrumentation technique.

As a result, the last 3 decades have seen an explosion in the development of NiTi endodontic file systems, and tremendous progress has been made. Improvements in metallurgical technology allowed the development of various new instruments with innovative designs, blade geometries, and alloy thermomechanical treatments, resulting in improved efficiency.^1-7

NiTi rotary instruments for the mechanized preparation of root canals were developed by John McSpadden and Ben Johnson in 1990. The first-generation NiTi rotary files were characterized by instruments having passive cutting radial land (Figure 1), constant taper, and a neutral or negative rake angle. Examples of the first generation are McXim File (NT Company), GT system (Dentsply Sirona), LightSpeed (LightSpeed Technology), Pow-R (Moyco), ProFile (Dentsply Sirona), and Quantec (Tycom). The primary deficiencies of the systems in this group were the number of instruments required to achieve the complete canal preparation and the rather complex protocols needed.

Figure 1. Blade of a first-generation engine-driven file. The double arrow shows the radial land.

The second generation of NiTi engine-driven files appeared at the end of the 1990s. Instruments were manufactured with changes in their helical angles, tapers, and cutting angles. As a result, this generation’s engine-driven files had active cutting edges (Figure 2), improving their efficiency, and most of them were without radial land.

Figure 2. Second-generation file showing modifications on the cutting surface.

These enhancements led to fewer instruments required to accomplish complete canal preparation. In addition, some manufacturers applied a supplemental treatment on the file surface called electropolishing (EP). EP removes surface irregularities, cracks, and residual stress caused by the previous grinding process.⁸ However, only one study found that EP significantly reduces the resistance to cyclic fatigue while increasing the angle of deflection at failure.⁹

Examples of the second generation are EndoSequence (Brasseler), K3 (Sybron), ProTaper Universal (Dentsply Sirona), and Genius (Medidenta). Despite requiring fewer instruments, fractures were still a significant concern, and preliminary clinical guidelines were recommended, such as glide path and coronal preflaring, which reduced the occurrence of file separations.

In 2007, post-grinding thermomechanical procedures began to be used by the leading manufacturers initiating the third generation of instruments. Each company developed a different heat treatment method. Following the implementation of these technologies, the engine-driven files became safer, with enhanced performance in shaping ability, especially in the preparation of anatomical challenges, such as curved canals. At the same time, clinical studies reported lower fracture rates using these heat-treated files.^10,11

Examples of the latest generation are HyFlex CM (Coltène), K3XF (SybronEndo), ProFile Vortex Blue (Dentsply Sirona), ProTaper Ultimate (Dentsply Sirona), ZenFlex (Kerr), EdgeTaper Platinum (EdgeEndo), and Genius Proflex (Medidenta).  

THE RATIONALE FOR HEAT-TREATED NITI FILES

Originally, NiTi alloy was developed by the Naval Ordnance Laboratory (White Oak, Md) and named Nitinol, an acronym for nickel (Ni), titanium (Ti), and Naval Ordnance Laboratory (NOL). NiTi alloy used in endodontic instruments contains approximately 56 wt% nickel and 44 wt% titanium, resulting in a nearly one-to-one atomic ratio (equiatomic).¹²

This equiatomic NiTi alloy can exist in 2 different strain- and temperature-dependent crystal structures (Figure 3) called austenitic (cubic B2 crystal structure) and martensitic (monoclinic B19 crystal structure) phases.¹³  

Figure 3. NiTi alloy phase expressions (austenitic, transitional R-phase, and martensitic) with representations of the different atomic crystal structures.

Heat treatment is one of the fundamental approaches to adjust the crystalline transition phase of a metal alloy and improve its fatigue resistance. This modification is essential because several properties of each alloy phase expression are notably different. For example, the proportions of the austenitic phase (more rigid and with the spring-back effect) and martensitic phase (more flexible with permanent plastic deformation) determine different instrument performances.

The file is soft when the alloy is in its martensitic phase, and it can easily be permanently bent (also defined as controlled memory). In contrast, the austenitic phase is firm and returns to the original straight condition when the load is removed (spring-back effect, see Figure 4). From a practical point of view, martensitic instruments are recommended to be used in curved canals once they are supposed to provide better maintenance of the original canal path.^14-17

Figure 4. Representation of the spring-back effect. The applied load will deform the file temporally. However, the file returns to its original, straight position once the load is removed.

The major limitation of controlled memory (CM) instruments is that the martensitic alloy phase expression requires less load for deformation, meaning that the unwinding of CM files can be experienced more often, particularly in the initial prospection phase of instrumentation with small-diameter files.

In addition, predominant martensitic alloy phase expression under torsion has a high angular deflection to sustain great rotation before fracture (Figure 5); however, the torque needed to deform and fracture these instruments is lower than with austenitic instruments.^18-22

Figure 5. Representation of torsional load without separation on a martensite file. (a) The file tip locks inside the canal’s narrowest segment, (b) but the motor continues the clockwise file rotation. (c) The martensitic characteristic of high angular deflection allows [SC: for?]unwinding, visible deformation without separation.

Therefore, instruments whose alloys are mainly in the martensitic phase have more flexibility to deal with curvatures, but they tend to have more significant distortion in the face of forces contrary to their progress in the apical direction. It is concluded that the martensitic phase would be more attractive in instruments of a higher caliber, above 25 (ISO 25), for example.

In these instruments, the greater metallic mass factor influences flexibility negatively yet, in the meantime, collaborates with their resistance to harmful torsional fatigue. The martensitic alloy phase expression given by the heat treatment can help flexibility without decreasing the torsional strength. 

Different factors regarding torsional stress generation during root canal preparation have been identified in the literature. These include the type of canal curvature, instrument design and cutting efficiency, instrument size and canal size, contact area, preparation technique, preparation time, insertion depth and the number of insertions, correlation with displacement, motor source, kinematics, operative motion type, rotational speed and pecking speed, lubricant, experience, and alloy phase expression.²³

NiTi rotary files with high expression of the austenitic alloy phase will have more torsional fatigue resistance.²⁴ The alloy in a predominant austenitic phase expression is more suitable for thinner instruments, with a 20 (ISO 20) diameter or lower. Moreover, these instruments have lower metallic mass, leading to a natural flexibility that is given to the small diameter.

An interesting consequence of the various heat treatments in a NiTi alloy is the deposition of titanium oxide layers on the external surface of the instrument blade. Differences in the thicknesses of these layers are responsible for changing the exterior color of the instrument blade (Figure 6), which can be presented with different hues of violet, blue, or gold.²⁵

Some heat treatment formulas do not necessarily lead to the formation of a titanium oxide layer relevant enough to change the instrument’s color, such as M-Wire (Dentsply Sirona). 

Figure 6. Gold, blue, and violet blade colors due to different heat treatments that were applied (Genius Proflex [Medidenta]).

PURSUING THE RIGHT BALANCE BETWEEN FLEXIBILITY AND RESISTANCE: THE CUSTOMIZED HEAT TREATMENT

Instruments whose alloys are entirely in the austenitic phase have limited indications. For example, an instrument that is less prone to torsional fatigue may be desired in cases of retreatment, where the force exerted against the filling material to be removed results in a more significant torsional load on the instrument. However, these instruments, also known as super elastic (SE), have less flexibility and are more susceptible to cyclic fatigue fracture.

In addition, a slight deformation in the face of torsional forces is welcome, showing the operator that the force applied to the instrument’s progression is too great and there is an imminent danger of fracture. For instance, suppose the instrument locks within the canal walls and continues to rotate at a high torque.

In that case, it will inevitably reach its elastic resistance limit, and a torsional fracture will occur.

Therefore, it would be fair to say that the operator should choose an instrument alloy phase expression that is more austenitic for files during the initial apical approach, such as glide path instruments or smaller diameter instruments, as flexibility would be present due to the design and metallic mass. In contrast, these instruments need a performance surplus due to torsional fatigue resistance by a higher angular deflection.

On the contrary, files of greater caliber should present their alloy phase expressions in a more martensitic phase given their greater volume in mass and lesser flexibility. It is worth remembering that fully austenitic instruments must be relegated to specific functions, such as retreatment. If the same heat treatment is performed for all sizes, some will benefit from the accomplished metallurgical changes while others will be harmed. Therefore, one method doesn’t equally satisfy the needs for all sizes.

Until mid-2020, the scenario was that if the operator wanted to get the most out of heat treatment in endodontic instruments, he or she would have to mix and match different systems. However, considering that “other systems” implies a different protocol sequence and that no consensus or research is showing the results of this mix of instruments, evaluating the quality and safety of this mix-and-match option seems to be entirely empirical and only based on individual experiences.

Genius files were established in 2015 with a design that allowed rotary and asymmetrical reciprocal motion use. The improved generation of Genius files, Genius Proflex (Medidenta), was launched in 2020 as the first system to adopt customized heat treatments (Figure 7) to balance torsional strength and high flexibility in different sizes of files.

Figure 7. Genius Proflex file examples of the 3 different heat treatments applied. Small-diameter files (purple) received a more austenitic heat treatment, intermediate files (blue) received a more martensitic treatment, and larger files (gold) received the higher martensitic heat treatment.

With new instruments in the series and 3 tailored heat treatments, Genius Proflex showed a better balance between torsional resistance (more austenitic in the smaller caliber files) and higher flexibility (more martensitic in the larger caliber files) (Figure 8). 

Figure 8. As a result of the customized heat treatments applied for different diameters of files, Genius Proflex large files present a more martensitic alloy expression phase showing the same flexibility as the small-diameter files, which naturally offer more flexibility due to less metallic mass.

The thinner (ISO 13 .03, 17 .05, and 25 .04) instruments received a heat treatment with a more dominant austenitic phase, which led to a violet stain. The more martensitic, larger files (ISO 40 .04, 50 .04, and 60 .04) resulted in a golden color. There are also 2 intermediate instruments (ISO 30 .04 and 35 .04) whose heat treatment resulted in a bluish hue.

This mix of heat treatments leads to a differentiated performance of each instrument in the series, increasing resistance to the 2 biggest challenges presented during instrumentation (torsional and cyclic fatigue) at different stages of treatment. 

It seems that there is a trend toward customized heat treatments based on the metallic mass of the instrument. Since the launch of Genius Proflex in 2020, other manufacturers have presented systems with a differentiated heat treatment in the sequence, corroborating the original idea that the same heat treatment should not merely be applied to different file sizes.

One example is an instrument ISO 15 .04 whose alloy is in the martensitic phase. Indeed, the operator will have a lot of difficulties advancing apically given the high degree of distortion and ineffectiveness of the cut of this instrument.

Clinically, the instrument has an angular deflection angle up to the fracture that is so high that the instrument distorts, even before the dentin walls are cut, and the canal widens.

CLOSING COMMENTS

Instrument separation during shaping procedures with rotary NiTi systems is an undesired event that can lead to complex resolutions. The wide range of fracture rates reported in the literature (from 1.98% to 26%) highlights the unpredictability of this phenomenon in clinical practice. It could certainly be related to multiple factors, such as instrument design, number of uses, motor kinematics, root canal anatomy, or operator experience.

Extensive clinical and scientific knowledge was created about the benefits of file heat treatments and the predominant phases acquired. It is essential to know that different heat treatments lead to various instrument performances, helping to overcome the separation of instruments in different stages of instrumentation.

REFERENCES

1. Gavini G, Santos MD, Caldeira CL, et al. Nickel-titanium instruments in endodontics: a concise review of the state of the art. Braz Oral Res. 2018;32(suppl 1):e67. doi:10.1590/1807-3107bor-2018.vol32.0067 

2. Haapasalo M, Shen Y. Evolution of nickel-titanium instruments: from past to future. Endod Topics. 2013;29:3–17. doi:10.1111/etp.12049

3. Peters OA. Current challenges and concepts in the preparation of root canal systems: a review. J Endod. 2004;30(8):559–67. doi:10.1097/01.don.0000129039.59003.9d

4. Shen Y, Coil JM, Zhou H, et al. HyFlex nickel-titanium rotary instruments after clinical use: metallurgical properties. Int Endod J. 2013;46(8):720–9. doi:10.1111/iej.12049

5. Shen Y, Zhou HM, Zheng YF, et al. Current challenges and concepts of the thermomechanical treatment of nickel-titanium instruments. J Endod. 2013;39(2):163–72. doi:10.1016/j.joen.2012.11.005 

6. Zhou H, Peng B, Zheng YF. An overview of the mechanical properties of nickel-titanium endodontic instruments. Endod Topics. 2013;29:42–54. doi:10.1111/etp.12045

7. Zupanc J, Vahdat-Pajouh N, Schäfer E. New thermomechanically treated NiTi alloys – a review. Int Endod J. 2018;51(10):1088-1103. doi:10.1111/iej.12924

8. Kuhn G, Tavernier B, Jordan L. Influence of structure on nickel-titanium endodontic instruments failure. J Endod. 2001;27(8):516–20. doi:10.1097/00004770-200108000-00005 

9. Bui TB, Mitchell JC, Baumgartner JC. Effect of electropolishing ProFile nickel-titanium rotary instruments on cyclic fatigue resistance, torsional resistance, and cutting efficiency. J Endod. 2008;34(2):190–3. doi:10.1016/j.joen.2007.10.007

10. Shen Y, Zhou HM, Zheng YF, et al. Current challenges and concepts of the thermomechanical treatment of nickel-titanium instruments. J Endod. 2013;39(2):163–72. doi:10.1016/j.joen.2012.11.005 

11. Gambarini G, Piasecki L, Di Nardo D, et al. Incidence of deformation and fracture of twisted file adaptive instruments after repeated clinical use. J Oral Maxillofac Res. 2016;7(4):e5. doi:10.5037/jomr.2016.7405

12. Thompson SA. An overview of nickel-titanium alloys used in dentistry. Int Endod J. 2000;33(4):297-310. doi:10.1046/j.1365-2591.2000.00339.x 

13. Buehler W, Gilfrich J, Wiley RC. Effects of low-temperature phase changes on the mechanical properties of alloys near composition TiNi. Int J Appl Phys. 1963;34:1475–7.  doi:10.1063/1.1729603 

14. Sousa-Neto MD, Silva-Sousa YC, Mazzi-Chaves JF, et al. Root canal preparation using micro-computed tomography analysis: a literature review. Braz Oral Res. 2018;32(suppl 1):e66. doi:10.1590/1807-3107bor-2018.vol32.0066

15. Arslan H, Yildiz ED, Gunduz HA, et al. Comparative study of ProTaper gold, reciproc, and ProTaper universal for root canal preparation in severely curved root canals. J Conserv Dent. 2017;20(4):222–4. doi:10.4103/JCD.JCD_94_17

16. Bürklein S, Hinschitza K, Dammaschke T, et al. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Int Endod J. 2012;45(5):449–61. doi:10.1111/j.1365-2591.2011.01996.x

17. Plotino G, Ahmed HM, Grande NM, et al. Current assessment of reciprocation in endodontic preparation: a comprehensive review–part II: properties and effectiveness. J Endod. 2015;41(12):1939–50. doi:10.1016/j.joen.2015.08.018

18. Silva EJNL, Vieira VTL, Belladonna FG, et al. Cyclic and torsional fatigue resistance of XP-endo shaper and TRUShape instruments. J Endod. 2018;44(1):168–72. doi:10.1016/j.joen.2017.08.033 

19. Silva EJNL, Giraldes JFN, de Lima CO, et al. Influence of heat treatment on torsional resistance and surface roughness of nickel-titanium instruments. Int Endod J. 2019;52(11):1645–51. doi:10.1111/iej.13164 

20. Silva EJNL, Hecksher F, Antunes HDS, et al. Torsional fatigue resistance of blue-treated reciprocating instruments. J Endod. 2018;44(6):1038–41. doi:10.1016/j.joen.2018.03.005

21. Silva EJNL, Vieira VTL, Hecksher F, et al. Cyclic fatigue using severely curved canals and torsional resistance of thermally treated reciprocating instruments. Clin Oral Investig. 2018;22(7):2633–38. doi:10.1007/s00784-018-2362-9 

22. Pedullà E, Lo Savio F, Boninelli S, et al. Torsional and cyclic fatigue resistance of a new nickel-titanium instrument manufactured by electrical discharge machining. J Endod. 2016;42(1):156–9. doi:10.1016/j.joen.2015.10.004

23.Thu M, Ebihara A, Adel S, et al. Analysis of torque and force induced by rotary nickel-titanium instruments during root canal preparation: a systematic review. Appl Sci. 2021;11:3079 doi:10.3390/app11073079

24.Lopes HP, Gambarra-Soares T, Elias CN, et al. Comparison of the mechanical properties of rotary instruments made of conventional nickel-titanium wire, M-wire, or nickel-titanium alloy in R-phase. J Endod. 2013;39(4):516–20. doi:10.1016/j.joen.2012.12.006

25.Tian H, Schryvers D, Liu D, et al. Stability of Ni in nitinol oxide surfaces. Acta Biomater. 2011;7(2):892–9. doi:10.1016/j.actbio.2010.09.009 

ABOUT THE AUTHOR

Dr. Ramos received his DDS degree from the State University of Londrina in Brazil in 1987. He has a PhD in endodontics and is a former head of the endodontics department at the State University of Londrina. He has published 3 endodontic textbooks and has written more than a dozen chapters for various endodontic books. Living in the United States since 2012, Dr. Ramos lectures globally about streamlined endodontic protocols. He can be reached via email at carlos.ramos@medidenta.com.

Disclosure: Dr. Ramos is the director of clinical affairs for Medidenta.

Third Quarter of the Root Canal Game

We will use the molar No. 19 (Figures 1 to 3) as the example for these final steps.

Figure 1. Preoperative radiograph of tooth No. 19.

Figure 2. Postoperative photo following use of ProTaper Gold (Dentsply Sirona Endodontics).

Figure 3. Recall at 18 months.

Shaping: This ensures the removal of vital or necrotic pulp tissue and enables the sodium hypochlorite and, later, QMix (Dentsply Sirona Endodontics) to work in the canal and extend down to the apex. Shaping also opens the canals enough for obturation.

The best part about this RCT playbook is that you can use any orifice opener, glide path file, or set of shaping files. Just choose your desired file system. I use ProTaper Gold (Dentsply Sirona Endo-dontics) (Figure 4) and WaveOne Gold (Dentsply Sirona Endo-dontics) in my practice. I have completed thousands of cases with these file systems and have achieved excellent shaping results. 

Figure 4. ProTaper Gold.

Once you have completed the middle flare and glide path with the ProTaper Gold Shaper 1, move on to the ProTaper Gold Shaper 2 (Figure 5). Gently work this to length using 4 to 5 engagement/disengagements. At this point, it will slide and glide to working length easier than the S1, but it still may take 1 to 2 passes of 4 to 5 engagement/disengagements. The S1 is your workhorse and does a lot of what I call the “hard” shaping. Irrigate out the debris with sodium hypochlorite and recapitulate (negotiate to patency) with a #10 K-file. Always shape with bleach in the canals. Never shape dry.

Figure 5. ProTaper Gold S2.

Once the S2 reaches working length, proceed to the ProTaper Gold Finisher 1 (#20 tip) (Figure 6). This will usually fly to working length. These files shape the apical third and create a deep apical shape. If it’s a tight, twisty, curved canal, you can finish the shape with the F1, but since I am talking about “simple” root canal treatment, I usually finish with the ProTaper Gold Finisher 2 (#25 tip). In the same manner, work the F2 down to working length with 4 to 5 engagement/disengagements or slow in-and-outs. It may take one pass, or it may take 2 to 3. Take your time. Once you get to working length, gently run the F2 two to 3 times at or near working length to obtain a deep apical shape. Many dentists just “peck” the apex with their last shaping file and then wonder why the matching gutta-percha cone doesn’t fit to length or fits 2 mm short. Don’t be afraid to gently shape the apex. This will give you a deep apical shape, clean the apical foramen, and allow the cone to fit down to working length. Remove the Finisher 2 from the canal and inspect the end of the file. Are the flutes full of dental debris? If they are, then you are done shaping and do not need to upshape to the ProTaper Gold Finisher 3. 

Figure 6. ProTaper Gold F1.

Apical verification: This ensures that you have a deep apical shape and that the cone will fit to working length.

Once shaping is complete, gently verify the apical shape. If you finished with a ProTaper Gold F2 (#25 tip), select and place a #25 K hand file to working length. If it fits snugly to working length without much resistance and does not extend past working length, then apical shaping and verification are complete. If the #25 K-file stops 2 mm short of working length, you have not shaped the apical third adequately, and the soft gutta-percha cone will also stop 2 mm short of working length. Go back and reshape the apex. The easiest way to do this is to use the #25 K hand file in a reciprocating motion and gently advance it down to working length. If the #25 file won’t extend down to working length, remove it, irrigate, recapitulate with a #10 K-file, and work your way from a #15 to a #20 and finally back to a #25 K-file. You can also reshape the apical third with the ProTaper Gold F2. 

Once you feel that apical verification is complete, use the EndoActivator (sonic activation) (Dentsply Sirona Endodontics) with bleach in the canals and run it for 1 minute per canal. This enhances chemical disinfection and stirs up the bleach piranhas to eat more tissue and microbes.¹ 

Fourth Quarter of the Root Canal Game

Conefit: This ensures that the cones fit to the proper working length and are not seated short or long.

This step is often hurried through because you are now running out of treatment time, and the next patient is waiting in another treatment room. 

Still, take the appropriate time to perform a good conefit with quality cone-fit radiographs. Select the matching gutta-percha cone. In this case, select the micronized, conform fit ProTaper Gold F2 cones and place them into each canal one at a time. When they stop advancing, crimp the cone with cotton pliers at the reference point, and then remove the cone and measure to see if it advanced down to the correct working length. If a cone fits 1 mm long, then use scissors to cut 1 mm off the tip. If a cone fits approximately 1 mm short, then go back and gently shape to working length with a #25 K-file or the ProTaper Gold F2 file. 

Once you feel that the cones fit to the correct working length, place them back in the canals that are soaking with bleach and take a straight and a shift periapical radiograph. If the cone is right at the radiographic working length, then trim approximately 0.5 mm off the tip. If you are long, then cut back the appropriate length. Be as exact as possible here, and do not cut off too much of the cone. Keep at it until you have an excellent conefit (in the real world, this should just take minutes to achieve as long as you have shaped well).

Final disinfection: Now, remove the cones and suck out the bleach with a micro-vacuum or use paper points and irrigate with the final solution, QMix 2in1. QMix is a 2-in-1 irrigant that consists of EDTA and chlorhexidine² (Figure 7). This 2-in-1 solution removes the smear layer that forms circumferentially on the canal wall from shaping with the EDTA component and then provides a substantivity antibacterial effect with the chlorhexidine component.³ I have been using QMix for more than 5 years in my practice. The theory is that the EDTA removes the smear layer, and then the chlorhexidine can enter the exposed and open dentinal tubules and kill any hiding microbes. Dentinal tubules are essentially little caves that bacteria, viruses, and fungi can hang out in.³ 

Figure 7. Mix 2in1 Irrigating Solution (Dentsply Sirona Endodontics)

Place QMix with a side-vented needle and sonically agitate the QMix with the EndoActivator in each canal for 30 seconds^4,5 (Figure 8). Leave the QMix in the canals for at least one minute to remove the smear layer. Recapitulate one last time with a #10 or #15 K hand file. 

Figure 8. EndoActivator System (Dentsply Sirona Endodontics).

Paper points: This ensures the canals are dry, especially in the apical third.

Use a micro-vacuum (I prefer the EndoVac MacroCannula [Kerr Endo-dontics]) to suck out the QMix from all of the canals, and then dry with paper points. For efficiency, use the corresponding ProTaper Gold F2 paper points. You can also use any standard paper points. A good rule that I use in my practice is to use medium paper points if I finished the shape with a ProTaper Gold F1, coarse paper points if I finished with an F2, and extra coarse if I finished with an F3.

Warm Vertical Obturation: This ensures that you achieve a 3D “hermetic” seal.

Finally, it is time to fill and seal the shaped and cleaned canals. The goal of obturation is to 3-dimensionally hermetically seal the apex so microbes can’t escape or enter the root canal system. There are 4 ways to obturate a canal: (1) cold lateral, (2) warm vertical, (3) thermoplastisized gutta-percha (GuttaCore [Dentsply Sirona Endodontics] or Thermafil [Dentsply Sirona Endo-dontics]), and (4) single cone using a calcium silicate sealer like BC. In this article, we will focus on warm vertical obturation.

Pick up the “fitted and measured” gutta-percha cone with cotton pliers and butter the apical third with your preferred sealer (I use either Pulp Canal Sealer [Kerr Endodontics] or Ribbon Root Canal Sealer [Dentsply Sirona Endodontics]). Carefully place the buttered cone into the canal and gently push it down toward working length. Make sure the cone seats down to working length by checking that the crimped part of the cone is at the reference point. I then use the Gutta-Smart heat tip (Dentsply Sirona Endodontics) (Figure 9) or the EndoPro 270 (Brasseler USA) at 200℃ to “burn out” the coronal two-thirds part of the cone, leaving a 5-mm apical gutta-percha plug. To perform this technique, I prefer the black-sized tip for the Gutta-Smart heat tip or the 45/04 tip for the EndoPro 270. They are smaller and fit better into premolar and molar canals. Be gentle when using the heat tip. If it does not fit down to within 5 mm of working length, that is ok. Do not force it down the canal. Just go as far as it allows with the ideal goal of extending the heat tip to within 5 mm of working length. This allows the heat to travel down the 5-mm gutta-percha plug and to the apex. Select a small plugger (I prefer the Dovgan Pluggers with the white/green end [Prime Dental Supply]), dip the end into the sealer, and then gently tap or push on the softened, 5-mm apical plug and mold it into the irregularly shaped foramen. The goal is to obtain a nice, tight hermetic seal (in theory) and to prevent any microbial leakage.

Figure 9. Gutta-Smart (Dentsply Sirona Endodontics)

Backfill the coronal two-thirds of the canal with the Gutta-Smart Obturation Handpiece 25-ga tip (or any preferred backfill device). Place the 25-ga tip on top of the 5-mm apical gutta-percha plug, and slowly extrude the heated gutta-percha. Go slowly and allow the Gutta-Smart to push you out of the canal. I typically backfill the entire canal up to the orifice level in one shot. Select a larger plugger (Dovgan, black/blue end) and tap the gutta-percha down right at the orifice. Clean the extra sealer off the pulp chamber floor and walls with a small chloroform pellet, followed by alcohol (Pulp Canal Sealer) or just an alcohol pellet (Ribbon Root Canal Sealer).

Whew! This root canal is finally done. This is one for the books! 

CONCLUSION

Follow the root canal playbook to achieve effective, efficient, and excellent root canals (or, what I like to call E³ Endodontics). It will take practice, practice, practice, and a few missteps, but keep at it, and you will achieve endodontic success.

REFERENCES

1. Pasqualini D, Cuffini AM, Scotti N, et al. Comparative evaluation of the antimicrobial efficacy of a 5% sodium hypochlorite subsonic-activated solution. J Endod. 2010;36(8):1358-60. doi:10.1016/j.joen.2010.03.035

2. Kara Tuncer A. Effect of QMix 2in1 on sealer penetration into the dentinal tubules. J Endod. 2015;41(2):257-60. doi:10.1016/j.joen.2014.10.014

3. Azim AA, Aksel H, Zhuang T, et al. Efficacy of 4 irrigation protocols in killing bacteria colonized in dentinal tubules examined by a novel confocal laser scanning microscope analysis. J Endod. 2016;42(6):928-34. doi:10.1016/j.joen.2016.03.009 

4. Arslan D, Guneser MB, Dincer AN, et al. Comparison of smear layer removal ability of QMix with different activation techniques. J Endod. 2016;42(8):1279-85. doi:10.1016/j.joen.2016.04.022

5. Caron G, Nham K, Bronnec F, et al. Effectiveness of different final irrigant activation protocols on smear layer removal in curved canals. J Endod. 2010;36(8):1361-6. doi:10.1016/j.joen.2010.03.037

ABOUT THE AUTHOR

Dr. Pullen graduated from the University of Southern California Dental School in 1999 and completed a one-year AGD residency in Landstuhl, Germany, while in the US Army. He practiced as a general dentist for 5 years before attending the Long Beach VA Endodontic residency and graduating in 2006. Dr. Pullen started his own private practice in Brea, Calif, in 2007 and became board-certified in endodontics in 2013. He has 3 kids and enjoys surfing, reading, Brazilian jiu-jitsu, and hanging out with his wife and kids. Dr. Pullen runs both the live 2 Day Root Camp Boot Camp and rootcanalacademy.com online courses. He can be reached via email at reidpullen@rootcanalacademy.com. 

Disclosure: Dr. Pullen lectures for Dentsply Sirona. 

INTRODUCTION

Can you feel it? 

We all feel the stress of doing our next endodontic treatment to one extent or another. Why is that?

Stress is present because endodontics is the only dental discipline where we “do it in the dark,” and doing dentistry blind is stressful for any dentist. After entering an endodontic root canal system, we cannot “see” and “do” simultaneously. We lose our precious control. This loss is felt deep in our gut, and our mind agrees. Or maybe it is the other way around. Either way, we have all been there, looking at a pretreatment endodontic image, feeling anxiety and sometimes even threatened. You feel it, your staff feels it, and your patient feels it. It is not fun.

In preparation to receive this article’s full clinical value, I invite you to imagine for a moment that it’s Monday morning and you have found the canal entrance of your first scheduled endodontic patient. At this crucial treatment point, you find yourself experiencing the fear of one or more of the most common endodontic “stress points.” Stress is produced (1) because you cannot prepare or preserve the Glidepath for mechanical preparation; (2) because the canal is too calcified, coronally restrictive dentin prevents your “following” the canal to length, or you simply “can’t get down”; (3) because your mechanical NiTi file could break, stretch, or result in a preparation that you cannot Conefit, 3D clean, and 3D fill; (4) from failing to prepare the proper shape for safe and predictable obturation in large or open apex canals; (5) from fear of canal blocking, ledging, transportation, or breaking a file in a sharp apical canal hook; or (6) because the master gutta-percha cone does not fit after all your effort. Yes, all these things are stressful. They don’t have to be.

These endodontic treatment stress points and concerns are real. What if these stresses could instead be turned into fun, confidence, and successful production? What if a Shaping System allowed you to master your endodontic endgame? What if the stress that you experience while waiting for the final obturation image to appear were replaced with the excitement of anticipating a solid, well-designed obturation with multiple portals of exit visibly sealed? What if, in seeing the final obturation image, your inner child exploded with joy and satisfaction? Allow me to introduce ProTaper Ultimate (Dentsply Sirona). The motivation for creating Ultimate was to transform these endodontic stresses into stressless endodontics. Here is how it was done.

In May 2001, I wrote the introductory Dentistry Today ProTaper article, titled “Introducing a New Rotary System: Progressively Tapering Files.”¹ The revolutionary distinction of Shapers (progressive geometries) and Finishers (regressive geometries) was a first and lasting clinical value (Figure 1).² Today, almost 20 years to the day of that first article, I am writing the introductory Dentistry Today article for ProTaper Ultimate—an exploration and assembly of the essentials of endodontic preparation requirements for “appropriate” shaping, 3D cleaning and 3D filling.^3,4 Since 2001, ProTaper has saved more than 200 million teeth, 1,200 scientific articles have been written about ProTaper, and ProTaper has become the world’s most popular and recognizable endodontic file system brand. And yet, 2 years ago, it became clear that the endodontic landscape was changing due to further improved metallurgy, cleaning, and filling counterparts.

ProTaper Ultimate’s goals are to (1) advance minimally invasive endodontics (MIE), (2) simplify the technique, (3) facilitate a safer procedure, (4) treat a wider range of anatomy, (5) start with rotary file first to secure canal, and (6) discover the carefully balanced and essential engineering transition elements from Glidepath through Finisher. The intended result was to design a fresh and almost peaceful clinical experience that fosters fun, predictability, and improved productivity. The most important task of all was to create a desirable Shaping system that dentists would want to use.

ProTaper Ultimate is not just a Shaping System but the first of a 3-part launch from Dentsply Sirona. The first part of this Trifecta is ProTaper Ultimate. Part 2, the 3D cleaning system (SmartLite Pro [Dentsply Sirona]), and part 3, the revolutionary 3D filling system (carrier-based obturation with AH Plus Bioceramic Sealer [Dentsply Sirona]), will be coming soon.

THE ULTIMATE ANSWER TO ENDODONTIC STRESS:
THE MAKING OF A “WOW” 

When given the opportunity 2 years ago to reinvent a revelatory endodontic Shaping System that would produce a gap between “what is” and “what could be,” we knew the assignment would be an overwhelming invitation since most metallurgies, rake angles, tip designs, sizes, and shapes had been tried in endodontics. Given the enormous success of ProTaper, which is identified as the most recognizable Shaping System in the world, we knew we had a challenge on our hands. ProTaper Gold is also the overwhelming choice of North American endodontists, but could it be made even better?⁵ Dentsply Sirona designers Dr. Cliff Ruddle and Prof. Pierre Machtou, and I all agreed that if we could not produce a “WOW” (our adopted working title), the project should end. The endodontic world did not need just another file. In fact, since ProTaper’s first-generation launch 20 years ago, there have been an estimated 300 file systems that have come and gone. Their clinical value was not sustainable. In fact, as I am writing this, there are 3 new file system advertisements on my desk promising, at one point or another, everything from total enlightenment to financial freedom. No wonder they come and go. Dentists want to trust that a product does what it promises to do.

Standing still was never a ProTaper option, but the first months attempting to pioneer a WOW felt like standing still. Special things don’t just happen; it is always about intention. Making a WOW took Dentsply Sirona backing; Swiss master engineers Nicolas Crevoisier and Gilbert Rota (the original ProTaper engineer in 1995); an acclaimed machine factory in Ballaigues, Switzerland; craft; passion; patience; vision; and decades of experience. Finally, we needed an additional “creative” ingredient: imagination. Imagination allowed an opening into a future that could forge the fusion of technical precision, uncompromised functionality, and exclusive design augmentation.

In the beginning, the development team was searching for our WOW, but our efforts were all in the wrong places. We were looking for this big WOW, and yet our breakthrough was instead found in many little places. Some believe the relationship between effort and results is not linear and follows what scientists call a “Power Law.”⁶ According to the Power Law Theory, certain small changes in a complex system can produce exponentially more, and often sudden, results than others. These small changes can cause a cascade among the connected parts, like knocking over the first domino in a long row. We just had to find the right changes. In short, by paying attention to the essential few elements of an endodontic Shaping System, a “less but better” complex was discovered—at last, the WOW we had been looking for. The answer that had been so hard to find suddenly became clear and simple. Certain critical little changes throughout the Ultimate system produced exceptional and expanding performance values.

ProTaper Ultimate has made incredible advancements in the foundational technology for designing, developing, and building an endodontic Shaping System that makes radicular preparations more accessible, more predictable, and more affordable for all dentists. The endo-
dontic transformational power of ProTaper Ultimate was discovered. Time is our biggest cost, and Ultimate’s efficiency and file-robustness result in an endodontic treatment that is energizing and time-saving and frees you to do more. This feeling is deeply rewarding, fulfilling, and gratifying all at once.

NEW FILE FEATURES AND CLINICAL VALUE 

The mantra, the sequence, and the ProTaper confidence have always come from a plan for predictability. Look how simple Ultimate makes it: purple, white, and yellow—sculpted endodontic preparations as easy as 1, 2, 3. I will now introduce the entire ProTaper Ultimate family: a simple, wide range of endodontic shaping solutions (Figure 2a).

1. Slider (purple) (Figure 2b). 

Goal: As always, determine working length. The Slider then prepares a safe, mechanical “Glidepath” for the Shaper. The use of “rotary first” invites you to think profoundly different (both with confidence and caution). 

 Distinguishing Features and Clinical Value: 

• We have thought about the Glidepath differently for some time now.^7-10 Nature’s untouched root canal walls often provide a sufficiently smooth tunnel or slide from orifice to physiologic terminus that can be safely followed by this newly designed mechanical file. Simply changing the word Glidepath to “Slidepath” immediately changes a clinician’s mindset and makes the preparation for rotary a much easier game. Nature presents what we now prefer to call “nature’s Slidepath.” Studies show that the Slider can successfully follow nature’s untouched canals ~63% to 80% of the time if we use masterful restraint with professional patience and supreme delicacy (as discovered by the designers and Dentsply Sirona user evaluations). The Slider will find its way by following nature’s natural tunnel, usually in 1 to 3 passive passes, while cradling the handpiece in the palm of your hand. Do not push or peck with your index finger; resist this temptation that will always be present. The index finger is the most dangerous finger in all rotary or reciprocation shaping because it wants to do something, and that something is to push, which leads to breakage, blocks, ledges, transportations, and perforations. If the Slider does not slide after a few self-restrained “follow” passes, return to K-files 6, 8, or 10 and manually prepare a Slidepath.¹¹ 
• The Slider is a purpose-specific M-wire mix of variable parallelogram cross sections producing enhanced performance vs ProGlider square cross sections.
• Using the Slider at 400 rpm and 5 Ncm vs ProGlider at 300 rpm contributes to enhanced cutting efficiency.
• The Slider’s alternating, offset machining produces reduced friction and greater space for debris removal.

2. Shaper (white) (Figures 2c and 2d) .

Goal: Simplify the system by combining 2 Shapers into 1. Integrate ProTaper Gold S1 and S2 in order to design a unique and harmonious transition from the Slider through the Finishers. 

Distinguishing Features and Clinical Value:

• The Shaper is a single Shaper.
• The Shaper uses purpose-specific gold heat treatment.
• The Shaper is produced from a 1.0-mm maximum flute diameter (MFD) vs 1.2 mm MFD of ProTaper Shaper S1 and S2, increasing flexibility and preparing an MIE narrower body.
• The Shaper has alternating offset machining and a variable parallelogram cross section generating flexibility without compromising cutting efficiency and resulting in greater resistance to cyclic fatigue.

3. Finisher 1 (F1) (yellow). 

Goal: Achieve an MIE body while maintaining the iconic ProTaper Deep Shape. 

Distinquishing Features and Clinical Value:

• Made from purpose-specific gold heat treatment (Figure 2e).
• A 1.0-mm MFD metal vs a 1.2-mm MFD metal, enhancing flexibility and apical preparation control and  fashioning a slimmer body shape.
• Alternating, offset machining.
• Carefully balancing better flexibility without compromising cutting efficiency.
• Bernoulli’s principle funnel shapes facilitate 3D filling. (Bernoulli’s principle of fluid dynamics is named after Daniel Bernoulli, who published it in his book Hydrodynamica in 1738.)

4. Finisher 2 (F2) and Finisher 3 (F3) (red and blue, respectively, when needed). The goal, features, and clinical value are the same as with F1. Note that the Slider through the F3 represents the ProTaper Ultimate core. 

5. Auxiliary Finishers FX and FXL (when needed). 

Goal: Expand ProTaper Deep Shape preparations with Finishers for larger canals.

Distinguishing Features and Clinical Value:

• Same as F1 to F3, except for 1.2 mm MFD for FX and 1.0 mm MFD for FXL, with purpose-specific blue heat treatment. 

6. SX Auxiliary Shaping File (when needed).

Goal: To improve flexibility and preserve superb cutting efficiency. 

Distinguishing Features and Clinical Value:

• The new Ultimate SX file, thanks to a variable parallelogram cross section and alternating offset machining, is an auxiliary instrument that combines flexibility without compromising cutting efficiency. This advantage was not the case with the current ProTaper Gold SX version. The new Ultimate SX file has the flexibility advantage of the current ProTaper Gold SX and the cutting efficiency behavior of the traditional, non-heat-treated ProTaper Universal SX file.

7. Manual files (when needed). 

Goal: Shape anatomy that has an abrupt and sharp apical turn or all anatomy where rotary is not available or not preferred.

Distinguishing Features and Clinical Value:

• Same as rotary counterparts (Figure 2f).
• The ability to produce a deep shape and an MIE body with just a few manual and safe rotations.

When comparing ProTaper Ultimate to ProTaper Gold F1 and F2:

• Ultimate F1 is 13% more flexible than ProTaper Gold F1.
• Ultimate F1 is 75% more resistant to cyclic fatigue than ProTaper Gold F1.
• Ultimate F2 is 30% more flexible than ProTaper Gold F2.
• Ultimate F2 is 30% more resistant to cyclic fatigue than ProTaper Gold F2.

HOW THIS NEW SYSTEM OVERCOMES THE SIX MOST COMMON ENDODONTIC STRESSES 

Common Stress Point No. 1: Glidepath failure. 

Ultimate solution: The Slider is intended to be the first instrument to slip and slide down the virgin canal. Fill the chamber with viscous chelator. Cradling the handpiece in the web of your hand (no pushing or “trying” to reach length) allows the file to follow nature’s canal walls to length (Figure 3a). If the file slows, remove it, clean the flutes, irrigate with NaOCl or an additional viscous chelator, and repeat until length is reached. If the Slider does not easily progress to length, manually prepare the Slidepath in those last few millimeters. Remember that the Slider reaches length ~63% to 80% of the time, as discovered by the designers and Dentsply Sirona user evaluations. For the other 20% to 37% of the time, return to a manual Glidepath. Please note the newly engineered SX Auxiliary file consistently removes canal access dentin triangles that may prevent easy entrance and apical progression of the Slider. The watchword for the Slider is restraint.  

Common Stress Point No. 2: Calcification.

Ultimate Solution: The Shaper is a single Shaper replacing ProTaper’s S1 and S2 Shapers. The Shaper’s reduced MFD and improved cutting efficiency make it easy to remove restrictive dentin along the Slider-prepared walls. It may take several passes while cleaning flutes between passes and irrigating with NaOCl. Finishers will gracefully follow the Shaper’s path. The watchword for the Shaper is patience (Figures 3b to 3d).

Common Stress Point No. 3: The finishing file breaks or stretches or the prep does not produce 3D cleaning or 3D filling.

Ultimate Solution: As already noted, core Finishers F1, F2, and F3 have more flexibility and greater resistance to cyclic fatigue than ProTaper Gold Finishers. The new design makes them more robust yet highly efficient and produces repeated shapes within the same tooth without metal distortion. This feature produces consistent and accurate Deep Shapes for confidence in 3D cleaning and 3D filling. The watchword for Finishers F1 to F3 and the “Ultimate Look” is effortless (Figures 3e to 3k).

Common Stress Point No. 4: Treating larger canals.

Ultimate Solution: The FX and FXL enable clinicians to predictably prepare larger canals where there is sufficient tooth structure. If severe apical reverse architecture is present, an apical plug may be required. The watchword for the FX and FXL is easy (Figures 3l to 3n).

Common Stress Point No. 5: Fear of breaking a rotary file or blocking, ledging, or transporting sharp apical curvatures.

Ultimate Solution: Manual files have all the same geometries as Ultimate Rotary files and enable the clinician to prepare sharp apical canal curvatures in 1 to 3 turns of the handle. The watchword for Manual files is safety. 

Common Stress Point No. 6: Conefit.¹² 

Ultimate Solution: Precision-machined Ultimate gutta-percha master cones exactly replicate and fit the last 3 mm of the Ultimate apical preparations and are also designed to have an intimate fit throughout the canal preparation, making single-cone, vertical-compaction-of-warm-gutta-percha, and carrier-based obturation easy and predictable. The watch phrase for conefit is conefit is a fit (Figures 3o and 3p). 

SIX CARDINAL RULES

Never deviate from these 6 rules; they will always work.

1. Always start with the Slider. This allows you to slide down nature’s very own, already existing Slidepath without using a manual file anywhere from ~63% to 80% of the time; otherwise, return to a manual Slidepath. Never force it. Once you have the Slidepath, the rest is easy!  
2. Always shape the coronal two-thirds of restrictive dentin with the Shaper. This allows you freedom and effortlessness in preparing a Deep Shape apically while preserving pericervical coronal dentin.
3. Always finish radicular preparation with the Finisher that cuts apically. If F1 does not visually cut dentin seen in its apical flutes, advance to F2, and if F2 does not visually cut dentin in its few apical millimeters, then advance to F3. If F3 is devoid of apical dentin shavings, then consider FX, and if FX is not cutting dentin on visual inspection, advance to FXL. If the FXL fails to prep the few apical millimeters, then consider an apical barrier due to reverse apical architecture (Figure 4a). This allows you to prove that you are finished shaping and are ready to confidently fit cone.
4. Always conefit after Ultimate flutes are filled with apically carved dentin while the canals are still wet. This allows you to confirm that the Deep Shape and Body Shape are present in your preparation and correspond perfectly with the last finisher used.
5. Always use EDTA, then NaOCl 3D cleaning protocol with EndoActivator (Dentsply Sirona) or SmartLite Pro, after conefit. This allows you to remove the smear layer, eliminate tenacious bacteria still present after shaping, and digest remaining pulp.
6. Always obturate at the time of shaping unless the patient is symptomatic or if you first want evidence of healing, such as sinus tract closure or endo-perio improvement. This allows you to obturate when you are most knowledgeable and familiar with the root canal system anatomy.

THE ULTIMATE CHALLENGE:
AN INVITATION TO DISCOVER FOR YOURSELF

It’s now time for the “Ultimate challenge”: Test ProTaper Ultimate’s performance against your current preferred rotary shaping system (Figure 4b) by keeping a diary of preparation comparisons—simplicity, efficiency, safety, durability, consistency, predictability, control, and Conefit accuracy and ease the first time.

CLOSING COMMENTS 

As dentists, we have the same goals. We are self-selected. We want to help people, we do not want to cause any harm, and we are artists in our own way. We are Michelangelos in a different medium. Even though our desired outcomes are different, our intentions are the same as a Michelangelo sculpture: “Trifles make perfection, and perfection is no trifle.” My purpose in writing this article is to have you experience your own endodontic artistry in your practice through ProTaper Ultimate’s transformational potential.

Twenty-five years ago, the groundbreaking ProTaper concepts were conceived, and in 2001, they were first embraced by ProTaper advocates in difficult cases, then in easy cases, and eventually in all cases. ProTaper Ultimate is a fresh story in the ProTaper legacy, and, as we venture into the future, I predict Ultimate will be the world’s go-to endodontic-preparation rotary system.

Today is an historical milestone for dentistry as thoughtful endodontic technologies have been brought together to build a generation of dentists free from endodontic stress and serving a greater patient condition. We stand on the precipice of a new era of endodontic performance and experience.

Until the present, “root canal words” such as “tranquil,” “bliss,” and “fun” would never have found their way into mainstream endodontic language. But now, it’s too good and it’s true. Finally, we’re back to my beginning question: Can you feel it?

What are you waiting for?

ACKNOWLEDGEMENT

Graphics in this article  were produced in collaboration with Advanced Endodontics, Santa Barbara, Calif.

REFERENCES

1. West JD. Introduction of a new rotary endodontic system: progressively tapering files. Dent Today. 2001;20(5):50-2, 54-7. 

2. West JD. The Evolving Look of ‘The Look’. Dent Today. 2019;38(6):62-66. 

3. West JD. The pendulum swings: “minimally invasive” vs “maximally appropriate.” Dent Today. 2019;38:8-10. 

4. West JD. The Endodontic Triad: ‘Dead or Alive?’ Dent Today. 2021;28-35. 

5. West JD. Survey from American Academy of Endodontists. Scientific Zoom Session; April 2021.

6. McKeown G. Essentialism: The disciplined pursuit of less. Crown; 2020. 

7. West JD. The endodontic glidepath: “secret to rotary safety.” Dent Today. 2010;29:86-93. 

8. West JD. Manual vs. mechanical endodontic glidepath. Dent Today. 2011;30:136-140. 

9. West JD. Glidepath implementation: “return to the beginning.” Dent Today. 2011; 30:90-97. 

10. West JD. Restraint: The lost art of endodontics. Dent Today. 2018:100-103. 

11. West JD. Perforations, blocks, ledges, and transportations. Overcoming barriers to endodontic finishing. Dent Today. 2005;24(1):68-73. 

12. West JD. The cone fit: An essential step to creating exceptional endodontic obturation. Dent Today. 2005;24(5):102-105. 

ABOUT THE AUTHOR

Dr. West received his DDS degree from the University of Washington, where he is an affiliate professor, and his MSD degree in endo-
dontics from Boston University, where he was honored with the Distinguished Alumni Award. Dr. West is founder and director of the Center for Endodontics in Tacoma, Wash, where he is also in private endodontic practice. He can be reached at (253) 377-2007 or via email at johnwest@centerforendodontics.com.

Disclosure: Dr. West is co-inventor of ProTaper.