Treatment outcome in endodontics: the Toronto Study. Phase III: initial treatment.

The 4- to 6-year outcome of initial endodontic treatment was assessed for phase III (1998-1999) of the Toronto Study. Of the 532 teeth treated, 248 were from discontinuers (excluded), 142 from dropouts, 10 extracted, and 132 (50% recall) examined for outcome: healed (no apical periodontitis [AP], signs, symptoms) or diseased. Phase III was analyzed alone and combined with phases I, II (n = 373 teeth). Logistic regression performed on the combined phases I-III sample identified significant (p < or = 0.05) outcome predictors: preoperative AP (OR = 3.5; CI 1.7-7.2; healed: absent, 93%; present, 80%), number of roots (OR = 2.2; CI 1.0-4.7; healed: 1 - 92%; > or =2 - 83%), and intraoperative complications (OR = 2.2; CI 1.1-4.5; healed: absent, 88%; present, 76%). Treatment technique (OR = 2.8; CI 1.3-6.1; healed: Schilder, 89%; alternative, 73%) was suggested as an outcome predictor in teeth with AP, requiring confirmation from randomized controlled trials.