Influence of several factors on the success or failure of removal of fractured instruments from the root canal.

The influence of several factors on the success rate of removal procedures of fractured endodontic instruments was evaluated postoperatively. In 105 teeth with 113 fragments removal attempts were undertaken using a wide range of techniques and instruments. All cases were analyzed with special regard to the following factors: type of tooth and root canal, site of fragment in relation to root canal curvature, length of fragment, and type of fractured instrument. Success of treatment was defined as removal or complete bypassing of the fragment. Of 82 instruments in molars (maxillary: 32, mandibular: 50), 56 were removed or bypassed (max.: 26, mand.: 30). Of 16 fragments in premolars (max.: 12, mand.: 4), 8 could be removed or bypassed (max.: 6, mand.: 2). Of 14 fragments in canines and incisors (max.: 7, mand.: 7), 13 could be removed completely (max.: 6, mand.: 7). When the fragment was localized before the curvature 2 of 18 cases failed, when localized inside the curvature 13 of 31 cases failed and when localized beyond the curvature 15 of 33 cases failed. Anatomical factors favorable for removal were: straight canals, incisors and canines, localization before the curvature, length of fragment more than 5 mm, localization in the coronal or mesial third of the root canal, reamer or lentulo spirales. In molars removal procedures were most successful in the palatal canals of maxillary molars.