Cognitive Dissonance in Endodontics.

Dentistry December 12th, 2006

One of the three people who regularly read my blog, Dr. Mommy, just reminded me of a classic article in Endo by Bender and Seltzer:

Authors: Seltzer S, Bender IB.
Title: Cognitive dissonance in endodontics.
Journal: Oral Surg Oral Med Oral Pathol
Date: Oct 1965
Citation: 20(4):505-16

Purpose/Objectives: To determine if cognitive dissonance is present in endodontics

Discussion: Cognitive dissonance is the existence of views, attitudes, or beliefs which are inconsistent or incompatible with one another but, nonetheless are held simultaneously by the same person. It is believed that if the three basic principles, the endodontic triad, are followed faithfully treatment must be successful. These principles are; a) thorough debridement of the root canal, b) sterilization of the root canal, and c) complete obturation of the root canal. Dissonance begins to occur when the principles are followed and failure results or through intention or neglect the formula is not followed and success results. One of the examples cited was the technique of culturing canals. Many false negative cultures exist yet many endodontists state, a poor evaluation tool is better than no evaluation tool at all. Any success obtained from treatment in the positive canals cultured is ascribed to a significant reduction in the number of microorganisms and removal of most of the inflamed or necrotic tissue. Complete obturation should yield a good result, assuming the root canal is well debrided and sterilized. Again cognitive dissonance occurs when inadequately obturated canals are evaluated as being successful. The hollow tube theory, proposed by Rickart and Dixon in 1931 has been cited as definite evidence that complete obturation of the root canal is essential for periapical repair. As long as this is accepted as evidence there is no dissonance. However, doubts increase when in routine full mouth radiographs teeth with partially filled root canals and complete absence of PA pathosis exist. How these areas regress and disappear if the canals are not filled does not follow the triad. How can failures be explained rationally when we have faithfully followed an acceptable formula for success? Is success based on radiographic criteria, clinically asymptomatic patients, or histological evaluation?

Conclusions: In spite of faithful adherence to a basic principle a failure can still result. The endodontic triad has some dissonance inherently. To obtain the questions that remain unanswered more research is needed and re-evaluations of previously accepted facts are in order. One must be willing to stop ignoring the dissonance and admit that treatments sometimes fail, for there can be no attempt, at solution, of a nonexistent problem.


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  • Dr. Mommy, D.D.S.

    i think people use the old excuse of “hey, look at that crappy root canal what succeeded, i can get away with doing a quick job like that, let’s book 25 minutes for a 16!”. i spend at least an hour and a half on molars, start to finish, and if i’ve broken it up into pulpectomy first, then i spend a good solid hour cleaning, shaping, and irrigating the canals. i have had cases that have failed for a number of reasons, despite my best efforts, but at least i can go to bed at night knowing that i tried my best.

    does this article also take into account success/failure rates relative to the presence or lack of a permanent full coverage restoration like a crown? i see a lot of failing endos that look decent on radiographs (i know that doesn’t mean anything, but you get my point) that have huge composite resins and i can guess that the failure may be related to leakage as opposed to improper technique. what do you think?

  • Ameloblast

    Endo failure is simply because of infection. That could be bacteria that were not killed off in enough numbers through the procedure, or it could be from coronal leakage.

    Leakage can happen with crowns or fillings as final restorations.

    I don’t recommend a crown for every tooth that has had an endo because not every tooth that needs endo is structurally compromised (eg, many trauma cases). The main purpose for a crown after endo is for cuspal coverage in order to minimize the possibility of coronal fracture.

    Studies that have looked at the outcome of endo (in vivo) with respect to coronal restoration have been retrospective and have merely looked at the quality of the restoration regardless of whether it was a crown or filling (Trope).

    My view is that almost all of our short term endo failures (less than 5 years) are because of inadequate canal disinfection and not coronal leakage. The cores that we put into endo accesses are usually so deep that coronal leakage would take a while to get to the canals and would usually become visible as a marginal deficiency on a bite wing way before the endo is compromised.

    As an aside. Quite a few retreatments that I do show no signs of coronal leakage, but once I get through the core I find moisture (pus) where the gutta percha starts. This is likely because the core wasn’t packed tightly enough into the tooth leaving voids above the gutta percha and/or salivary contamination during the procedure.

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