Principle–driven endodontics: creating excellent results

Sept. 1, 2009
As I think of a subject for this column each month, my first question is “What can I share that has value for a general practitioner doing routine endodontic treatment?”

by Richard Mounce, DDS

For more on this topic, go to and search using the following key words: principle–driven endodontics, rubber dam, Dr. Richard Mounce, Endo File.

As I think of a subject for this column each month, my first question is “What can I share that has value for a general practitioner doing routine endodontic treatment?”

What makes this question tough is that there is a phenomenal diversity of experience, equipment, and skill level among clinicians doing endodontics in North America. There's also a fair bit of mythology and white noise clouding the issue from various sources, all touting one method over another.

Endodontic therapy should be principle–driven. The materials that are used are of secondary importance. Excellence is not the result of using the latest and greatest technology, but rather using this technology appropriately in a principle–driven sequence.

I have a unique vantage point from which to write and teach from doing dozens of hands–on courses and lectures globally each year. I observe firsthand both how clinicians learn and what their barriers to change tend to be. Interestingly, pre–existing biases tend to slow learning and progress more than any other single factor I observe. In addition, and more importantly, on some levels, there is misunderstanding over what constitutes the basic goals and principles guiding root canal therapy and a lack of understanding of canal anatomy.

Several basic principles are reviewed here to guide the general practitioner performing routine endodontic treatment.

1. Endodontic therapy should be performed on teeth that are or can be made restorable. A significant number of teeth (10%) referred to me are: a) nonrestorable, b) restorable only after a periodontal intervention such as crown lengthening, c) already vertically fractured, or d) at high risk of future vertical fracture. Treatment planning with restorability as one component of a much larger set of considerations is an essential component of creating a well–performed long–term result.

2. Informed consent should be exhaustive before access is made. Many patients in my specialty practice have never had root canal treatment explained to them. They are also unaware of what restorative treatment will be needed after the retreatment.

3. The rubber dam is the legal and ethical standard of care. Treatment should not be initiated without the rubber dam.

4. Canal instrumentation should be conservative in that prepared shapes should create a tapered funnel with narrowing cross–sectional diameters that allow optimal irrigation throughout the entire canal system, from the orifice to the minor constriction (MC). Prepared canal shapes should leave the tooth structurally sound and not risk iatrogenic outcomes or moving the position of the original canal. Specifically, minimal tapers should be prepared that are continuous from the orifice to the MC and leave the MC at its original position and size.

5. Hand files should be employed before rotary nickel titanium (RNT) files in order to assure that the canal is open, patent, and negotiable before (RNT) enlargement.

6. Pumping RNT files into roots repetitively is unproductive, irrespective of the brand of RNT file used. Optimal RNT use is passive, gentle, and done with the intent of engaging a minimal amount of the canal wall with each insertion.

7. Throughout treatment, at all costs, patency should be achieved and maintained. After the insertion of every RNT file, it has immense value to irrigate and reassure patency with small hand files.

8. Prior to obturating the canal, the clinician should be absolutely certain of the position of the MC. The MC should be located and confirmed with a variety of means, including electronic, bleeding point, possibly radiographic, and via tactile feel.

9. Do not place obturation material into the root unless you are certain the master cone or obturator is placed to the MC (i.e., the true working length). I use RealSeal master cones .06/20 that are trimmed to fit to length, and RealSeal One Bonded Obturators.* Aside from a lack of correct canal preparation, many less–than–optimal obturations occur because the clinician is not sure of the absolute position of the MC or the final termination point of the master cone or obturator. As the apex of any canal becomes more “open” or blunderbuss, the case is increasingly complex and should be referred.

10. Finally, the value of the early coronal seal cannot be overstated. The placement of a coronal seal is directly related to long–term endodontic success. Ideally, the build–up should be placed as soon as the root canal is completed.

I welcome your feedback.

*SybronEndo, Orange, Calif.

Dr. Richard Mounce lectures globally and is widely published. He is in private practice in endodontics in Vancouver, Wash.

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