Incidence and types of dentinal defects and instruments defects after preparation of moderately curved root canals using 3 rotary Ni-Ti systems (In vitro study)

Abstract

NiTi rotary instruments are widely used as they decrease operator fatigue, shaping time required, and procedural errors. Unfortunately, rotary NiTi files might produce increased friction and stress on the canal wall, causing dental cracking in root dentin. These cracks can propagate and cause vertical root fractureand tooth loss. Fracture of NiTi instruments could occur with little to no visible signs of plastic deformation; this could not be observed without magnification. Aim of the study was to evaluate incidence of dentinal defects and instrument defects after root canal preparation of moderately curved root canals using three different rotary NiTi systems (BioRace, M-Pro and 2Shape). Seventy lower first molars were collected and immediately stored in distilled water. Angle and radius of curvature of mesial roots was calculated using facial and proximal radiograph according to Pruett method by using Image J software and only moderate angle and radius of curvature for roots were selected. Samples were randomly divided into three experimental groups. Statistical analysis of the experimental groups showed that there was no significant difference in the angle and raidius of curvature between these groups and were classified according to the type of rotary file system used as follows.