Endodontic accountability: The “X” factor, part 9

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Dr. John West discusses knowledge, skill, and willingness in endodontics 


I have an agreement with Alaska Airlines. If I arrive late, they leave without me! I also have an agreement with Mother Nature. She has the same agreement with you. If we clean, shape, and seal her root canal system, Mother Nature has the capacity and agreement to heal with a 100% success rate minus some number.


Call it “X.” As endodontic clinicians, we have come to learn that “X” is not the size of the lesion of endodontic origin (LEO) or the histology of the LEO. The presence or absence of a sinus tract is not an “X” factor. In fact, as endodontic clinicians, we know that LEOs heal whether pulps are vital or non-vital. Mother Nature just does not care. She only cares that our endodontic shapes “follow” her original root canal system anatomy and that we produce what I have come to know as, and prefer to call, the Endodontic Seal. The “X” factor is really our knowledge of what to do, our skill in doing it, and lastly, and perhaps the most differentiating factor of all, is our willingness to do it. The “X” factor is us: the clinician and the endodontic anatomy.

This ninth article of Anatomy Matters chronicles six examples of the “X” factor and my experience of its role in endodontic success or failure. The purpose of this series has been to archive in one place examples of clinical cases that give evidence that anatomy does matter and what we can biologically, structurally, and mechanically do about it in order to optimize our endodontic performance.1-8

Patient Case Reports

Patient No. 1:Portal of exit significance from “coast to coast.” (Figures 1A-1K)

west 01Underfilled endodontic portals of exit (POEs) have potential biologic significance at any location along the three-dimensional walls of the radicular root structure. An endodontic failure may have underfilled or unfilled POEs located apical, sometimes mid-root, and sometimes furcally. Patient No. 1 presents with duplicable percussion and palpation pain. The pretreatment image suggests a furcal and apical LEO (Figure 1A). The distobuccal gingival crevice has an 8-mm narrow precipitous periodontal pocket probing (Figure 1B). Diagnosis: Underfilled root canal system resulting in an endo-perio periodontal vector. Treatment plan — options: Remove/replace or attempt to restore. Patient chose to attempt furcal repair, measure subsequent furcal healing and, if successful, proceed with nonsurgical endodontic retreatment in order to produce a radicular Endodontic Seal. On endodontic access, considerable hemorrhage occurred due to previous furcal perforation (Figure 1C). Mineral trioxide aggregate (MTA) repair better demonstrated accurate radiographic furcal condition. Modified periapical and periapical images are shown after MTA repair (Figures 1D and 1E). Figure 1F showed satisfactory furcal radiographic healing, and clinically gingival crevice resisted gentle probing, suggesting an improved predictability of success if the Endodontic Seal could be technically finished (Figures 1G-1I). Nonsurgical retreatment became justifiable and finished (Figure 1J). Subsequent 10-month posttreatment resulted in good osseous repair (furcal and apical), as well as gingival repair (Figure 1K). 

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Patient No. 2: The “silent tooth killer.” (Figures 2A-2C)

There are five kinds of endodontic resorptions.9 None of them are good. However, internal resorption has the capacity for repair if nonsurgical endodontics is successfully completed before the internal resorption reaches the root surface. Lateral radicular resorption perforations often produce an asymmetric portal of exit that is challenging to seal. Usual funnel-shape obturation hydraulics was not possible, and resorptive lateral POE seal requires a skillful approach. Patient No. 2 presented with apical LEO coupled with previous post placement surrounded by internal root resorption (Figure 2A). The post was successfully removed using the Ruddle post extractor after first loosening with ultrasonics (Figure 2B). Endodontic nonsurgical retreatment was finished, and 16-month posttreatment confirmed successful healing of the periodontal ligament and lamina dura and no apparent progression of internal resorption (Figure 2C).

Patient No. 3:  “Iatrogenic and natural underfilled portals of exit” in the same fixed bridge abutments. (Figures 3A-3L)

Patient No. 3 presented with post perforation, apical underfilling of FPD maxillary right lateral incisor and simultaneous lesion of endodontic origin of central incisor abutment due to necrotic and gangrene pulp. Bridge could not be easily removed even with CORONAflex crown and bridge remover from KaVo. A surgical treatment plan was discouraged due to possible existing coronal leakage and therefore need for improved coronal seal after nonsurgical retreatment. In addition, surgical seal of mid-root perforation presented an access and technical challenge (deemed probable mid-root POE) and esthetic challenge due to risk of possible gingival black triangle with full surgical flap, especially if patient were to have a high smile line. Anatomy matters at any time and in any place. For this patient at least four needed POE seals were anticipated: maxillary right lateral incisor apical endodontic underfilling and lateral root perforation. For the maxillary left central incisor, apical POE and lateral POE were suggested by location of gutta-percha cone tracing sinus tract to lateral mesial border of root. Accesses were safely made through both FPD abutments. Nonsurgical retreatment of the maxillary right lateral incisor and nonsurgical treatment of the maxillary left central incisor resulted in complete endodontic healing validated at 2-year posttreatment records (Figures 3A-3L).

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Patient No. 4. “Biology vs. structure vs. time.” (Figures 4A-4F)

Patient No. 4 presented with a 10-year previous endodontic procedure and palpation sensitivity. The periapical image implied apical and lateral underfilled POEs. While nonsurgical retreatment was successful, insufficient care was taken to preserve the mesial and distal ferrule (Figures 4A-4F). While the tooth benefits from a healthy attachment apparatus and new crown 10 years later, endodontic clinicians must be mindful and skillful to protect the tooth’s ferrule, particularly the lingual ferrule of maxillary anterior teeth, the facial ferrule of mandibular anterior teeth, and the buccal-lingual ferrule of posterior teeth. 

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Patient No. 5: “We never know for sure.” (Figures 5A-5D)

Patient No. 5 presents with sinus tract tracing to mandibular right first molar coronal third of furca. Pulp tested non-vital. Location of offending POE(s) was unclear, but proper shaping and cleaning enabled 3D seal of culprit anatomy with subsequent osseous and clinical healing (Figures 5A-5D). We will never know what endodontic anatomy was responsible for this patient’s LEOs. Was it the so-called main canals or the almost entire canal that I missed clinically but was picked up with SybronEndo (previously Kerr Endo) Pulp Canal Sealer? We will never know for sure. From Mother Nature’s perspective, she cared very little at this moment. She is always whispering to us, “Clean me, shape me, and seal me.” In return, she promises healing.   

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Patient No. 6: “Which POE don’t you want?” (Figures 6A-6D)

Which POE don’t we want could be answered only if we knew which POEs were essential for endodontic predictability. We don’t. And that’s the whole thing. Endodontic clinicians can never clean too much, can never shape just right, and can never obturate too thoroughly. There will always be a “sweet spot” of cleaning, shaping, and obturation based on the effectiveness of the technologies of the day. In 2001, when patient No. 6 complained of swelling and palpation symptoms, a periapical image revealed a mandibular right canine FPD abutment with a surrounding LEO and with internal resorptive sites. In addition, a lower right crowned premolar with an underfilled root canal system was causing an adjacent LEO of its own. The gingival crevice probed within normal limits. 

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Emergency care (access, cleaned endodontic anatomy, and closed) was successful, and patient was treatment planned to nonsurgically treat patient’s canine and nonsurgically retreat underfilled lower right premolar. Thirteen-year posttreatment validates osseous repair, and patient remains asymptomatic (Figures 6A-6D).


So there we have it. We have a problem, or we can simply say we have a situation requiring smart thinking. We also have a plan. Endodontic disease comes from pathogens escaping from inside the root canal system. We also know without a cause endodontic disease does not occur. We also know that if we eliminate the cause of endodontic disease, the sequelae of endodontic disease (LEOs) will “predictably” heal. So our endodontic job is clear and simple: Prevent LEOs where they do not exist, and cure LEOs where they do exist. No disease source, no disease. Mother Nature made the rules. She agrees to stay healthy or heal if we can prevent or heal LEOs by nonsurgically or surgically cleaning, shaping, and obturating the root canal system. Anything short of the Endodontic Seal means success must be achieved differently: good host resistance, presence or absence of LEO in the first place, virulence of pathogens, and time.

The question that is unresolved is, What is good enough?  To me, the unequivocal answer is, Good enough is not good enough. Most dentists try to finish everything they start — I suggest we start only what we can finish well. This is not a call for perfection. This is a call to do our best; to “Do It Right.” 

In a nutshell, my 10-part endodontic series entitled Anatomy Matters is simply a reminder and an invitation. The reminder is that we are accountable for the result. Success is not dependent on the phase of the moon, the status of the marketplace, whether our favorite sports team won or lost, the lesion is too large, or some teeth just don’t heal. Success “X” factor is us. No labs, does not really matter if our patients brush their teeth, no one to blame. But this is not about blame. This is about responsibility for the result. 

And so, finally, the invitation: To be responsible for the endodontic result. Slow down; make a perfect access that allows for unrestricted access into the canals but preserves precious ferrule; produce a reproducible glidepath for safe manual and mechanical shaping; irrigate more; agitate the proper irrigation more; irrigate with the most effective endodontic irrigants and devices; precisely fit the gutta-percha cone or carrier-based verifier; use the most three-dimensional technique depending on the length, width, and curvature of the canal and depending on your experience; pay as much attention to the coronal seal as the radicular seal; marry your patients back to their restorative dentists; and finally schedule posttreatment recalls in order to measure your outcome in 6 months, 1 year, 5 years, 10 years, and beyond. We don’t get what we want; we get what we measure. Not only does the great endodontic clinician do it well, our teeth have to last a long time.

Mother Nature has offered us her agreement. We can comply or commit. The choice is ours, and we make that choice with every motion we make in the endodontic treatment. We have thousands of choices in every given patient treatment. What will your treatment mechanics choices be during all those motions, moments, and movements for your next patient?  

For Mother Nature, the “X” factor is the difference that makes the difference. Are you willing to be that difference?

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1. West J. Anatomy matters. Endodontic Practice US. 2012;5(2):14-16.

2. West J. Anatomy matters — part 2. Endodontic Practice US. 2012;5(4):26-27.

3. West J. Anatomy matters part 3. Furcal endodontic seal heals furcal lesion of endodontic origin. Endodontic Practice US. 2012;5(6):22-24.

4. West J. Anatomy matters. Long-term case report. Endodontic Practice US. 2013;6(1):50-51.

5. West J. Anatomy matters. Root canal system anatomy only matters when it matters. Endodontic Practice US. 2013;6(2):56-58.

6. West J. Anatomy matters. Do lateral canals really matter? Part 6. Endodontic Practice US. 2013;6(3):52-53.

7. West J. Anatomy matters. “What’s it all about?” Part 7. Endodontic Practice US. 2013;6(4):52-54. 

8. West J. Anatomy matters. “Could it all simply be a coincidence?” Part 8. Endodontic Practice US. 2013;6(5):52-55.

9. Harrington GW, Steiner DR. Periodontal-endodontic considerations. In: Walton RE. Torabinejad M, eds. Principles and practice of endodontics. 3rd ed. Philadelphia, PA: W.B. Saunders Company; 2002;466-486.





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