INTRODUCTION: The use of motor-driven nickel-titanium (Ni-Ti) files in root canal preparation have numerous advantages. However, it might lead to dentinal crack formation which greatly affects the endodontic treatment prognosis. Therefore, new Ni-Ti files are developed with different heat treatments to enhance file flexibility, thus reduce stress concentration during root canal preparation.
AIM OF THE STUDY: To compare the incidence of dentinal defects produced by two motor-driven Ni-Ti systems; Hyflex EDM and MPro files using stereomicroscopic analysis.
MATERIALS AND METHODS: This study was conducted on thirty mesio-buccal root canals of human mandibular molars. All teeth were examined under a stereomicroscope to exclude any dentinal defects before instrumentation followed by decoronation and sectioning of distal roots. The root canals were randomly divided into three equal groups according to the file system used. Group I: Hyflex EDM files with continuous rotation motion. Group II: MPro files with continuous rotation motion, ending the preparation till tip size 25 in both groups. Group III: unprepared canals (negative control). All roots were sectioned at 3, 6, 9 mm from the apex using a precision cutter device. Stereomicroscope analysis was performed in all sections. Data were statistically analyzed.
RESULTS: All groups (including the control group) showed no dentinal defects with no statistically significant differences between the test groups and the control group at all levels.
CONCLUSIONS: The new generations of heat-treated rotary files could produce root canal preparation with less dentinal defects owing to their enhanced physical and mechanical properties.