Clinical analysis of 493 nonsurgical root canal retreatments

Objective Clinical data of 493 endodontic failure cases were analyzed,to evaluate the factors affecting the effect of root canal treatment.Methods Four hundred and ninety three endodontic retreatment teeth of 405 patients were analyzed,clinical examination,pretreatment and posttreatment radiographs,and effect after clinical management were recorded,to determine the faults that contribute to the endodontic treatment failure.Results A total of 115 anterior teeth,91 premolars,and 287 molars were included,72.2% of failed teeth showed apical radiolucency,94.1% showed under-filled canal,1.6% with over-filled canals,the rate of missing canals,calcified canals,ledge and transportation,foreign body in canals,perforation in pulp cavity or root were 28.0%,27.2%,41.0%,5.5%,3.0%,respectively.Among of them,307 teeth were symptomatic,340 had poor coronal restoration.Endodontic retreatments of 470 teeth were conducted favorably,and 23 teeth were pulled out during to endodontic failure.Conclusion The study indicated that factors that associated with endodontic failure involve in inadequate canal cleaning and shaping,under-filling canal,poor coronal restoration and complex root canal anatomy,the treatment outcome can improve when modern and normalized root canal therapy technique is applied.