Complications associated with fractured file removal using an ultrasonic technique.

A technique utilizing modified Gates Glidden burs and ultrasonics has recently been advocated to remove fractured instruments from root canals. Varying extents of tooth structure are removed during this procedure, potentially leading to complications. This study evaluated the in vitro and in vivo complications associated with fractured file removal. Fractured instrument fragments were removed from three different levels (coronal, middle, or apical third) of mesiolingual canals of extracted human mandibular molars. The success rate, frequency of perforations, and root strength were recorded for each group. Perforations and unsuccessful file removal occurred only with fragments lodged in the apical third. Fracture resistance declined significantly with more apically located file fragments. A review of 60 clinical cases showed similar rates of successful file removal and rate of perforations. Removal of a fractured file fragment from the apical third of curved canals should not be routinely attempted.