It has been stated that root canals performed by GPs have an 80% success rate. Renowned endodontist Dr. Allan S. Deutsch details three factors many dentists overlook. Mastering these endodontics elements will increase the success rate for root canal procedures.
As an endodontist with more than 40 years of clinical experience, instructor at our Hands-On Dental Education Center, international lecturer, and author, I enjoy sharing my knowledge with general dentists. It has been stated that root canals performed by general practitioners have an 80% success rate.1 Throughout years of teaching, I have found specific factors that many dentists overlook. The elements listed below are likely to increase the rate of success for your root canal procedures.
When performing endodontic access, magnification and illumination are the key. I recommend using a microscope, such as the Evolution Zoom (Seiler Instrument Inc.), if available. If not, 2.5x to 4.5x loupes are a bare necessity.
The roof of the pulp chamber can be removed by using a round bur. After gaining initial access to the pulp chamber, rotate the bur and withdraw in an occlusal direction to remove the pulp chamber ceiling. Then use a non-end-cutting diamond bur to push back the axial walls from the pulp chamber. Using the color of dentin on the floor of the pulp chamber is your best guide to finding the orifices to the canals. Do not remove dentin where the floor is already white. Seek those areas on the dentinal floor where the dentin is darkest. Pay special attention to where the lighter color dentin of the axial walls meets the darker color of dentin on the floor.
The darker portion of dentin on the floor will often have the configuration of a square, triangle, rhomboid, or diamond. The most likely location of the canal orifice will be at the apices of these shapes. If highly calcified, relieving coronal dentin from these sites will increase your chances of finding the canals. A sharp explorer is mandatory here. Finding the canal will produce a definite catch on the explorer when it finds the entrance into a canal.
Not finding, and subsequently not instrumenting, the MB2 canal is a very large source of many endodontic failures. As previously noted, by following the darker portion of dentin, if present, this canal is most likely located in the A, B, or C position of a molar (figure 1).
Proper irrigation of canals
Unfortunately, endodontic instrumentation alone does not remove 100% of bacteria and debris from the canal. Many studies have shown the limited ability of instrumentation alone to debride and clean the canal.2-6 Wu et al. reported uninstrumented areas in 65% of instrumented oval canals.7
The most frequently used irrigant is sodium hypochlorite (NaOCl). This irrigant has a great advantage in that it dissolves necrotic tissue and kills bacteria quite effectively. However, it may not always kill Enterococcus faecalis. These bacteria can often be found in biofilm in the canal and tubules. They are persistent and often resistant to calcium hydroxide as well as NaOCl. E. faecalis seems to be especially prominent in endodontic cases that have had root canal treatment and are failing.8 The prevalence of E. faecalis in those infections ranges from 24% to 77%.
My endodontic protocol in the past was not only to use NaOCl, but to add 2% chlorhexidine to combat E. faecalis and also use EDTA to open the dentin tubules and remove the smear layer. Just over a year ago, I switched to a new irrigation product, Irritrol (Essential Dental Systems/EDS). This product combines EDTA and chlorhexidine (CHX), thereby shortening my procedural time. More importantly, Irritrol has a 99.99% disinfection rate compared to CHX at 20%. For additional activation of this two-in-one endodontic solution, I use a passive ultrasonic irrigation (PUI) piezo tip (#6 EDS). PUI tips are designed to activate irrigants ultrasonically, making them more effective within the canal to aid in removing biologic debris and the smear layer.
Thorough canal instrumentation
The goal is to clean the canal thoroughly and produce a canal shape that can be fully obturated. Furthermore, to ensure maximum root strength during the endodontic procedure, it is important to remove as little tooth structure as possible.
Endodontic shaping has evolved from hand instrumentation to engine-driven rotary or reciprocation. Rotary offers a continuous 360-degree rotation, which can lead to binding and broken instruments. Due to the possibility of these iatrogenic incidences, reciprocating endodontics has become increasingly popular. Reciprocation moves in a back-and-forth watch-winding motion. A few of the reciprocating systems on the market include WaveOne and WaveOne Gold (Dentsply), Reciproc (VDW), Endo-EZE (UltraDent), as well as Tango-Endo, Endo-Express, and SafeSiders (Essential Dental Systems).
I use the Tango-Endo system. This system moves in true reciprocation, oscillating at 30 degrees. This particular oscillation is preferable to that of other reciprocating systems, because it progressively increases the degree of movement until reaching full rotation. The Tango-Endo instrument system virtually eliminates file separation, providing greater root canal treatment success.
1. Christensen G. Ask Gordon: What percent of endodontics is done by GPs? DentistryIQ website. http://community.pennwelldentalgroup.com/video/ask-gordon-what-percent-of-endodontics-is-done-by-gps. Accessed April 26, 2017.
2. Hülsmann M, Stryga F. Comparison of root canal preparation using different automated devices and hand instrumentation. J Endod. 1993;19(3):141-145.
3. Hülsmann M, Schade M, Schäfers F. A comparative study of root canal preparation with HERO 642 and Quantec SC rotary Ni-Ti instruments. Int Endod J. 2001;34(7):538-546.
4. Hülsmann M, Gressmann G, Schäfers F. A comparative study of root canal preparation using FlexMaster and HERO 642 rotary Ni-Ti instruments. Int Endod J. 2003;36(5):358-366.
5. Versümer J, Hülsmann M, Schäfers F. A comparative study of root canal preparation using ProFile .04 and Lightspeed rotary Ni-Ti instruments. Int Endod J. 2002;35(1):37-46.
6. Hülsmann M, Herbst U, Schäfers F. Comparative study of root-canal preparation using Lightspeed and Quantec SC rotary NiTi instruments. Int Endod J. 2003;36(11):748-756.
7. Wu MK, Wesselink PR. A primary observation on the preparation and obturation of oval canals. Int Endod J. 2001;34(2):137-141.
8. Stuart CH, Schwartz SA, Beeson TJ, Owatz CB. Enterococcus faecalis: its role in root canal treatment failure and current concepts in re-treatment. J Endod. 2006;32(2):93-98.
Allan S. Deutsch, DMD, FACD, with 40-plus years of clinical experience, is a lecturer, author, and top authority in the field. He is the executive vice president, codirector of dental research, and cofounder of Essential Dental Systems, as well as cofounder of the tristate area’s Hands-On Dental Education Center. Dr. Deutsch holds 19 patents for coinventing revolutionary endodontic systems.