Evaluation of ultrasonic and sonic instruments for intraradicular post removal.

Ultrasonic instruments are a valuable asset for removing intraradicular posts from root canals before nonsurgical endodontic therapy. The purpose of this study was to evaluate the relative efficacy of post removal by ultrasonic and sonic devices. Fifty extracted teeth were instrumented and obturated. The canals were prepared and Parapost #5 posts were cemented with zinc phosphate cement. The teeth were divided into five groups, subjected to ultrasonic or sonic instrumentation and the time measured until post removal. Median values in minutes for the post extractions in each group were: Cavitron = 6.0, Enac = 8.3, and Neosonic = 41.2. Sonic instruments were generally unable to remove the posts. The results of this experiment indicate that the Cavitron and Enac ultrasonic units are significantly more efficient for removing posts than the Neosonic. Sonic instruments were not useful for post removal.