An SEM-based study of dentinal defects caused by four advanced rotary file systems

Introduction: The research examined and compared dentinal microcracks after biomechanical preparation using Protaper Next, Hyflex EDM, Waveone Gold, and Jizai rotary file systems in middle, apical, and coronal root canal levels. Material and Methods: 100 human-extracted permanent mandibular premolars have been divided into one control group and four experimental groups of 20 teeth each. The roots have been sectioned at 3, 6,9 millimeters from apex and studied under scanning electron microscope. A Fisher's Exact Test and Chi-Square have been utilised to record and analyse dentinal defects. Results: No microcracks were found in control group. All studied groups exhibited comparable distribution of dentinal microcracks in coronal, middle and apical section. Dental defects in middle third were more common in ProTaper Next than in the control group. Conclusions: In the study, all tested rotary systems resulted in some degree of dentinal microcracks. The middle third of the root canal was the most affected region, showing a statistically significant increase in defect formation.