Clinical analysis of failure factors in root canal therapy

Aim To analyze the failure factors in root canal therapy(RCT)by analysis of the failed cases.Methods 125 teeth of 206 patients were analyzed according to former treatment records,clinical examination,pretreatment radiographs,and root canal exploration during endodontic retreatment.Results 47.2% of failed teeth showed apical radiolucency,12.6%under-filled canal material without apical radiolucent area and 8.4% coronal leakage.When examined with X ray,84.2% of teeth indicated under-filling,and most canals of premolars and molars had poor taper.Most missed root canals were found in maxillary first molars and premolars.18.1% of teeth had complications such as ledge and apical transportation.Conclusions The factors associated with RCT failure involve cleaning,obturation and poor seal of root canal system resulted from inadequate shaping.Coronal leakage and missed canals also contribute to the endodontic treatment failure.