Factors affecting the outcome of orthograde root canal therapy in a general dentistry hospital practice.

OBJECTIVE: The goal of this study was to weigh the impact of patient-related, tooth-related, and treatment-related factors on therapy outcome in a series of consecutive patients. STUDY DESIGN: Eighty-four patients were included. Of these, 66 (79%) were available for recall after \u3e or = 30 months (mean = 46 months). Root canal treatments were performed using a standard protocol. At recall, teeth were scored by means of the periapical index (PAI), which was the dependent variable (dichotomized to sound/ unsound). Explanatory variables were patient age, integrity of the nonspecific immune system, smoking status, dichotomized PAI score before treatment, initial treatment versus retreatment, prior exposition of the root canal to saliva, stainless-steel hand versus NiTi rotary instrumentation, and quality of root filling. Unit of observation was the patient-individual. Data were analyzed using univariate tests and backward stepwise logistic regression analysis. RESULTS: After 5 steps with elimination of the least significant independent variable, status of the immune system (P = .05), initial PAI (P = .04), and root filling quality (P = .01) were found to be the indispensable predictors for treatment outcome. Using these 3 explanatory variables, the logistic regression model had a predictive value of 87%, compared to 91% with all 8 variables. Success rate at recall (PAI \u3c or = 2 without symptoms) was 88% (95% CI = 78, 94). CONCLUSION: The integrity of a patient\u27s nonspecific immune system, which has been neglected in earlier investigations, is a significant predictor for endodontic treatment outcome, and should receive more attention in future studies