A prospective cohort study evaluating the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions.

Abstract

AIM\nTo evaluate the impact of various predictors on the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions after a minimum of 2 years.\n\n\nMETHODOLOGY\nOne hundred and twenty previously root canal treated symptomatic mandibular first molars with periapical lesions which were diagnosed as symptomatic apical periodontitis or acute apical abscess with localized intraoral swelling were included. Root canal retreatment was performed by an experienced endodontist using a standardized treatment protocol. The teeth were followed-up clinically and radiographically and the radiographic outcome was assessed depending on the modified periapical index scale (PAI). The cumulative success proportion and the influence of predictors on the outcome of the root canal retreatment were analyzed using Kaplan-Meier analyses and long rank tests, and the hazard ratios for the predictors were also investigated using Univariate Cox Proportional Hazard regression analysis at a significance level of 5%.\n\n\nRESULTS\nOf the one hundred and twenty teeth, 103 teeth were re-examined with the 85% recall rate. The cumulative success rate was 88% in which 64% were healed and 24% were healing, and failure rate was recorded as 12%. None of the preoperative predictors including age, gender, soft tissue tenderness, intraoral swelling, size of the lesion, PAI score, apical level and density of root canal filling before root canal retreatment, nor intraoperative predictors such as active exudate drainage, density of root canal filling after root canal retreatment and restoration type had an influence on the outcome of root canal retreatment (P>0.05). The only factor that significantly reduced the success rate of root canal retreatment was the apical level of the root canal filling; when it was more than 2mm short of the radiographic apex in teeth that apical patency was not established (P=0.023), the success was significantly lower.\n\n\nCONCLUSIONS\nRoot canal retreatment in symptomatic mandibular first molars with periapical lesions resulted in a success rate of 88%. None of the predictors had a significant influence on the outcome, except for the apical level of root canal filling length after root canal retreatment with short root fillings being associated with significantly more post-treatment endodontic disease.