Numerous prognosis studies have evaluated the effect of individual factors on outcome.
Objective: The purpose of this study was to investigate simultaneous effect of several potential factors on endodontic treatment outcome.
Methods: This study comprised 200 endodontically treated teeth with 441 roots. Diagnostic and treatment information was abstracted from patient records. Follow up examination was conducted by one endodontist 4±0.5 years postoperatively, and each tooth/root was analyzed for periradicular status. Outcome criteria were modified from Strindberg. Data were subjected to univariate and multivariate analysis.
Results: The presence and the extent of preoperative periapical pathosis had the strongest effect on endodontic treatment outcome (p<0.0001). In teeth/roots with preoperative normal pulp and normal periapex (n=25), with successful outcome, instrumentation level (Mean ± SEM working length) was away from radiographic apex (1.24±0.13mm), unlike in teeth/roots with failing outcome (0.20±0.09mm; p<0.005). However, in teeth/roots with pulp necrosis and apical periodontitis (n=124), with successful outcome, working length level was closer to radiographic apex (0.55±0.12mm), than in teeth/roots with failing outcome (1.73±0.30mm; p<0.0005). Logistic regression models confirmed significant effect of preoperative apical periodontitis on endodontic outcome; compared to normal pulp with normal periapex, risk value for pulp necrosis with apical periodontitis, was in favor of failure, if the roots had the same instrumentation level (Odds ratio=3.21; p<0.05). Furthermore, in teeth/roots with pulp necrosis and apical periodontitis, a millimeter loss in working length (away from radiographic apex), increased the chance of treatment failure by 15.5% (p<0.05).
Conclusion: Endodontic outcome is a multi-factorial phenomenon. The major factor influencing endodontic treatment outcome is the presence and the extent of preoperative periapical pathosis.