Types of surface defects and incidence of fracture after root canal preparation using different single file systems at different torque settings using SEM (In vitro study)

Abstract

Objectives:-This study is an attempt to evaluate surface changes and incidence of fracture of One shape and Neoniti rotary files after root canal preparations of lower permanent molars, under different torques, using SEM.Material and methods: Total 26 files were used, 2 Control (one from each system), Group I (12 oneshape file) and Group II (12 Neolix files), each was further divided into Sub group A(low Torque 2N/cm) and Sub group B (High Torque 4N/cm)respectively.Results showed that even the new files suffered from surface defects. No used instruments free of surface defects even under low or high torque. Different torques cause statistically significant difference between One shape and Neolix files in terms of disruption of cutting edge and metal flash only. ConclusionClinicians should be aware because all files are predisposed to wear and fatigue, so small files should have improved quality control by the manufacturer as they are highly prone to failure especially in curved canals or under high torque or even if single used.