Treatment outcome in endodontics: the Toronto study--phases 3, 4, and 5: apical surgery.

INTRODUCTION: The long-term outcome of apical surgery performed on root-filled teeth presenting with post-treatment apical periodontitis has been the subject of debate; therefore, current evidence is required to support the prognosis of this important procedure. The objectives of this study were (1) to assess the long-term outcome of apical surgery and (2) to identify significant outcome predictors in Phases 3-5 of the Toronto Study, pooled with the previously reported Phases 1 and 2. METHODS: The 4- to 10-year outcome of apical surgery was prospectively assessed by a blinded, independent, calibrated examiner and dichotomized as "healed" (periapical index score 45 years, 84%, 10 mm, 53%). CONCLUSIONS: In this 4- to 10-year cohort study, the outcome was better in subjects >45 years old, teeth with inadequate root-filling length, and crypt size of