Why do we Need Endodontic Microsurgery?
Nonsurgical endodontic treatment, or root canal treatment, achieves a high rate of clinical success despite the anatomic and pathologic challenges of the procedure. Success in cases without periapical extension of pathosis is better than 90%, while studies show that infected root canals with an extension of pathosis into the periapical space have a decreased degree of healing. A nonhealing endodontic lesion is recognized by persistent pain and/or swelling, possibly with radiographic changes indicating increasing periapical bone loss. Inflammation of the periapical tissue (symptomatic apical periodontitis) is the source of this persistent pain, and given enough time, can also manifest with radiographic evidence of an enlarged ligament space or the formation of an apical osseous lesion from the resulting bone loss and swelling of the soft tissues. Instances of endodontically treated teeth that do not appear to be healing are not automatic indications for extraction and replacement with an implant. In many of these cases, a tooth may be scheduled to undergo nonsurgical retreatment with the aim of further disinfecting the root canal space to permit healing of the apical periodontitis. In instances where nonsurgical retreatment cannot solve the problem a significant number of persistent nonhealing cases can be saved by endodontic microsurgery with a predictably favorable prognosis.
Endodontic microsurgery (apicoectomy) in its broadest sense is the treatment performed on the root apices of an infected tooth, followed by placement of a filling (retrofilling) to seal the root end. In the past, this surgical procedure was performed by endodontists, oral surgeons and general practitioners using the then-traditional techniques of preparing the canal space with a round bur attached to a straight handpiece and using amalgam as the root-end filling material. Advances over the past decades, supported by ongoing research, have led to a refinement of these techniques, materials and instruments. These advancements are centered on the use of the surgical operating microscope to provide unsurpassed magnification and illumination for all phases of the treatment process.
As a result, the procedures have changed in ways that significantly affect the success, the overall case selection, the application for this now-predictable procedure, as well as the postoperative healing sequelae. Today’s apical surgery is more correctly termed endodontic microsurgery, due to the significant aid of the surgical operating microscope, which is fundamentally and significantly different from the traditional technique. Studies looking at the success of traditional apical surgery, indicate that it is almost fifty percent less successful than current microsurgical success data.
The microsurgical materials and instruments that define the technique of apical surgery as performed by endodontists are the main reasons for this elevated success and enhanced ability to retain teeth otherwise slated for extraction. The microscope enables accurate visualization, identification and treatment of infected extranumeral canals, isthmuses and irregular anatomy unreachable with traditional instrumentation techniques. Anatomic studies over the years, using various methods of evaluation, consistently reveal the complex anatomy that must be addressed when the root canal space becomes infected and must be cleaned and shaped. Research continues into improvements in instrument design and irrigation techniques that will enable the dentist to more completely clean and shape these complexities. There are instances, however, where endodontic microsurgery offers clear advantages over orthograde endodontics and can increase success rates. Root dentin is composed of dentinal tubules that bacteria are known to penetrate; sometimes through the entire thickness of the root to the cementodentinal junction. This penetrating bacterial load poses a potential etiology for the apical pathosis seen in the nonhealing of some orthograde endodontic cases. The root canal’s apical anatomy can be even more challenging to access and clean due to multiple portals of exit that can leave the root at sharp angles with small radii of curvature. In situations like these, stainless steel or nickel-titanium files may not be able to negotiate these areas without a risk of file separation, therefore inhibiting proper cleaning and disinfection of the root canal space. In addition, apical resorption may alter apical anatomy making the root end more difficult to effectively treat nonsurgically.