Damage to root dentin during retreatment procedures

Introduction: The aim of this study was to explore the influence of retreatment procedures on the appearance of defects on the root canal walls. Methods: Two hundred mandibular premolars were divided into 4 groups. One group was left unprepared. The rest of the teeth were prepared with ProTaper files up to size F4 and filled with gutta-percha and AH26. One group was left filled and received no further treatments. The filling material was removed from the remaining teeth either with ProTaper retreatment files or with Hedstr€om files. Roots were then sectioned and inspected under a microscope. Data were analyzed with the nominal regression test (a = 0.05). Results: No defects were observed in the unprepared group. Retreatment groups showed significantly more defects than the initial treatment group (P < .05).There was no difference between the appearance of defects after retreatment with Hedstr€om files and ProTaper retreatment files. The remaining dentin thickness and level of the root did not significantly influence the appearance of defects. Conclusions: Retreatment procedures result in more defects than initial treatment. When assessing the outcomes of endodontic retreatment, the substantial damage to the root canal walls should be considered