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

The 4- to 6-yr outcome of initial (first-time) endodontic treatment was assessed for Phase II of the "Toronto Study." In total, 442 teeth were treated by using flared preparation and vertical compaction of warm gutta-percha or step-back preparation and lateral compaction. With 126 teeth excluded (discontinuers: deceased and relocated patients), 163 dropouts, and 31 extracted, 122 (48% recall) were examined for outcome: "healed" (no apical periodontitis [AP], signs, symptoms) or "diseased" (AP, signs, or symptoms). Phase II was analyzed separately and combined with Phase I (n = 242), using Chi-square and Fisher's exact tests (p < or = 0.05). The healed rate (combined sample, 85%) differed significantly for preoperative AP (absent, 93%; present, 79%), treatment technique (flared preparation and vertical compaction, 90%; step-back preparation and lateral compaction, 80%), gender (females, 90%; males, 79%), number of roots (1-92%; > or = 2-81%), and root-filling length (adequate, 87%; inadequate, 77%). Logistic regression revealed increased risk of disease for preoperative AP (odds ratio = 3.3) and technique (odds ratio = 2.3). This study confirmed AP and highlighted treatment technique as the main predictors of outcome in initial treatment.