By Gary D. Glassman, DDS, FRCD(C); Kenneth S. Serota, MMSc, DDS, amd Frederic Barnett, DMD
The past two decades have witnessed a revolution in endodontic therapy, enabling the preservation, rehabilitation and reconstruction of damaged dentitions. Fifty million root canal procedures are performed annually in North America alone. Cross-sectional retrospective studies have shown a wide range of success rates for root canal treatment reflecting the complex nature of endodontic therapeutics. However, when treatment is performed to high technical and biological standards, success rates above 90 percent are to be expected. Endodontic retreatment failure has been reported in the literature to occur in the long term at a rate as high as 50 percent. The reported results are readily prejudiced by the design of the studies, the techniques employed, the operators performing the treatment, the recall time period, and the criteria used to define success or failure. Of equal concern are investigations conducted or financed by product manufacturers offering insincere claims of high success rates in many dental disciplines.
Outcomes vary based on the clinician’s experience and expertise, the type of tooth involved and a myriad of other clinical and biological factors. The common reasons for endodontic failure include missed canals, coronal leakage, post placement errors, blocks, ledges, perforations and transportations, fractures, inadequately filled canals, and separated instruments. These iatrogenic situations can be prevented. We must be prudent in treatment planning. Biologic failure is correctable and predictable.
Sometimes you must take a step back to move forward. Removing restorations in their entirety to access the root canal space can reveal caries, restoration failures, complete and incomplete fractures, leakage, missed canals, blockages, ledges and perforations. Exciting new technologies are available to dismantle restorations. Surgical operating microscopes enable topographic surveying of the intra-chamber and intra-radicular anatomy. New irrigating solutions eliminate smear layers, which remove canal contaminants and allow better adaptation of obturating materials. Ultrasonics facilitate the exposure of the complexities of the root canal system, removal of core material, posts, solid core and resin paste obturating materials. Mineral trioxide aggregate seals communications and perforations previously untreatable with any degree of effectiveness. Remarkably, cementum grows over this nonresorbable and radiopaque material, allowing for a normal periodontal attachment apparatus. Research into new materials continues unabated.
Careful case evaluation and treatment planning is the key to any successful outcome. Case selection for endodontic retreatment is based on restorability, periodontal condition, and the capability of superceding anatomic anomalies such as calcific, prosthetic, iatrogenic obstructions, and unusual canal morphology. The strategic value of the tooth as well as alternative treatment options must be considered. As long as these factors are assessed favourably and the economics is practical for the patient, the primary treatment consideration for endodontic failure should always be retreatment. Even if apical surgery is inevitable, its prognosis is better when it is immediately preceded by, or performed in conjunction with orthograde retreatment (a recent publication demonstrated a 92.5 percent success rate following endodontic surgery). Therefore, the injudicious, imprudent, and cavalier removal of teeth for the sake of expediency is not consistent with an optimal standard of care.
We have an obligation to our patients to provide them with the information that teeth, which in the past were doomed to extraction and replaced with either an implant, or a fixed or removable prosthesis can now and should be considered for endodontic retreatment that carries with it a very high success rate when performed with high quality. The retention of the natural dentition can predictably sustain function, speech, preserves associated structures, satisfies aesthetics and improves a sense of well-being.
While the same can be said of endosseous implants, however, there is a distinction in the proportionality of the application of the procedure. Their primary role relates to rehabilitation of patients who have lost soft and hard tissues from disease or trauma or those that have undergone extensive ablative surgery for cancers of the face and oral cavity. Removal of teeth for the purposes of expediency is analogous to “throwing the baby out with the bath water”. The art and science of dentistry is based on sophistication and excellence; and should never follow a path of lesser clinical resistance.
Perhaps the solution lies in the need for prevention, early diagnosis and a renewed appreciation of the most fundamental need of the natural dentition; occlusal harmony and balance. Maybe all that’s necessary is to revisit and renew the standard of care that fosters endodontic excellence. The fine line that delineates the controversy of retreatment versus extraction and implant placement would then be more accurately defined.
