If you are interested in an endodontic refresher lecture, come and join me next Thursday at the Pacific Dental Conference (PDC 2019). Two and a half hours lecture filled with pictures and videos demonstrating the initial endodontic treatment.
The only non-precious stone that I know is the pulp stone. One of the factors contributing to root canal failure is remaining infected pulp tissue and the pulp stones, if left behind unnoticed, are the main reason for trapping tissue and retaining infection. Pulp stone removal is therefore a crucial factor in achieving a successful result in endodontic treatment. The following case shows how a large pulp stone can result in failure of a reasonably well done root canal treatment by trapping infected tissue, hiding the MB2 canal and retaining infection.
Proper access cavity (i.e. adequately large and at the level of the CEJ) in order to visualize the outline of the pulp stone/chamber floor is the key in removing it completely. In the above example the pulp stone is easily dislodged by troughing around it using a large diamond-coated ultrasonic tip and applying the energy directly to the calcified tissue. For demonstration and documentation purposes, no water was used in this case; however, it is highly recommended to use water for its cooling effect and in order to facilitate the debris removal.
Imagine the following scenario:
A busy day in practice! A patient comes in with tooth #2-6 (upper left first maxillary molar) being extremely sensitive to cold (a.k.a. a “hot tooth”). You notice a very old, large amalgam filling on the tooth which had been done over 2o years ago. No recent restorative changes in the area is reported by the patient. Breathing in air, blowing air on this tooth with an air-water syringe or applying ice to the tooth sends the patient through the roof. All other teeth in this quadrant are responding normally to cold test. Quickly and confidently, a pulpal diagnosis is reached (irreversible pulpitis), endodontic treatment is recommended, and the need for a full coverage crown is also emphasized after root canal treatment. Simple, right?
Well, not so fast!
You may miss a more serious issue with this innocent-looking tooth in need of JUST a root canal and a crown, you may lose the opportunity to properly inform your patient of possible outcomes of your treatment and you may end up performing unnecessary treatments for a tooth with no hope.
Just imagine the final conversation with the patient after a quick exploratory/pulpectomy procedure:
Me – “Ms. Black, unfortunately your tooth cannot be saved as I had suspected and warned you before we started the root canal procedure today.”
Ms. Black – “I am amazed Dr. E! [with a smile] You knew exactly what was wrong with my tooth. You called it.”
“A dentist who has not separated a tip of a file, reamer, or broach has not done enough root canals.” — Louis Grossman
There are essentially 2 reasons for rotary rotary instrument separation inside a canal:
1) Cyclic fatigue (file rotating inside a curved canal for extended period of time):
Factors contributing to cyclic fatigue are: overuse of rotary NiTi files, spending too much time inside the canal during instrumentation, canal curvature (degree and abruptness of the curvature), improper speed setting for the handpiece and the file tapers (larger tapers break faster).
2) Torsional fatigue (too much friction between the rotary file and the canal wall):
Factors contributing to torsional fatigue are: improper endodontic access, using too much apical pressure during instumentation, not following the proper sequence for a particular file system, not using lubricating agent/irrigants, using greater tapered files inside a tight/calcified canal and using handpieces with no torque control or auto reverse option.
Attempting to control the factors above will greatly minimize the risk of file separation. But even in a perfect situation, a patient’s canal anatomy can bring the man-made technology to its knees.
What to do if a file breaks inside a canal?
1. Stay calm. It is not the end of the world.
2. Try to remove it only if the separated portion is in the coronal segment of the tooth and not past the root curvature. This step also requires good magnification, illumination and proper tools (such as different ultrasonic tips).
3. Bypass it if the separated segment is apical to the curvature of the root using hand-instruments and finish the shaping of that canal with hand-files. Sometimes the separated file comes loose and can be easily flushed out.
4. Make it part of the filling if the file has completely blocked the canal. This may not affect the prognosis negatively [Crump and Natkin 1970, Spili et al. 2005] depending on the initial status of the pulp and whether or nor the separation happened towards the beginning or the end of cleaning and shaping stage.
5. Follow up the healing and the resolution of symptoms. Endodontic surgery may be needed if symptoms persist or the PA lesion does not heal.