Root canal preparation of maxillary molars with the self-adjusting file: a micro-computed tomography study.

INTRODUCTION The aim of this study was to describe the canal shaping properties of a novel nickel-titanium instrument, the self-adjusting file (SAF), in maxillary molars. METHODS Twenty maxillary molars were scanned by using micro-computed tomography at 20-μm resolution. Canals were shaped with the SAF, which was operated with continuous irrigation in a handpiece that provided an in-and-out vibrating movement. Changes in canal volumes, surface areas, and cross-sectional geometry were compared with preoperative values. Canal transportation and the fraction of unprepared canal surface area were also determined. Data were normally distributed and compared by analyses of variance. RESULTS Preoperatively, mean canal volumes were 2.88 ± 1.32, 1.50 ± 0.99, and 4.30 ± 1.89 μm(3) [corrected] for mesiobuccal (MB), distobuccal (DB), and palatal (P) canals, respectively; these values were statistically similar to earlier studies with the same protocol. Volumes and surface areas increased significantly in MB, DB, and P canals; mean canal transportation scores in the apical and middle root canal thirds ranged between 31 and 89 μm. Mean unprepared surfaces were 25.8% ± 12.4%, 22.1% ± 12.0%, and 25.2% ± 11.3% in MB, DB, and P canals, respectively (P > .05) when assessed at high resolution. CONCLUSIONS By using SAF instruments in vitro, canals in maxillary molars were homogenously and circumferentially prepared with little canal transportation.