Micro-computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file

Abstract

Introduction: The aim of this study was to assess the shaping potential of a novel nickel-titanium instrument, the self-adjusting file (SAF), in long oval root canals in distal roots in mandibular molars.

Methods: Twenty mandibular molars with long oval distal root canals were selected and scanned preoperatively and postoperatively by using micro-computed tomography at an original resolution of 20 μm. Canals were shaped with the SAF, three-dimensionally reconstructed, and evaluated for volume, surface area, canal transportation, and prepared surface. Data were statistically contrasted by using paired t tests and regression analysis.

Results: Preoperatively, canal volume was 7.73 ± 2.13 mm(3), and canal area was 42.83 ± 8.14 mm(2). Volumes and surface areas increased significantly (P < .001) by 4.84 ± 1.73 mm(3) and 3.34 ± 1.73 mm(2), respectively, and no gross preparation errors were detected. Unprepared canal surface varied between individual canals, and mean unprepared surface was 23.5% ± 8.9%. Prepared areas were significantly larger compared with rotary canal preparation done in a previous study. Canal transportation scores were higher in the coronal root canal third (106 ± 50 μm) compared with the apical third (81 ± 49 μm).

Conclusions: In vitro, preparation of long oval-shaped root canals in mandibular molars with the SAF was effective and safe. Moreover, shapes generated with the SAF were more complete compared with rotary canal preparation.