Factors influencing the long-term results of endodontic treatment: a review of the literature.

The purpose of this review of the literature is to examine the factors and their influence on the outcome of endodontic treatments, and also to attempt to have an authors' consensus concerning the impact of these factors on long-term results. The documentary research was conducted using the meta-analysis principles of critical reading of the literature. Two groups of factors can be identified regarding the outcome of endodontic treatments: those which influence the success of the procedure and those which do not significantly affect the success rate. Agreement is obtained in all studies on two major factors, the preoperative periapical status and the apical limit of the obturation, which appear to strongly influence the success of endodontic therapy. This review highlights the methodological problems of retrospective studies and points out the need for consensus regarding the evaluation criteria of root canal therapy.