DETECTION OF CRACK FORMATION FOLLOWING CORONAL FLARING WITH THREE DIFFERENT INSTRUMENTS USING TWO EVALUATION METHODS (IN VITRO STUDY)

INTRODUCTION: Coronal flaring is now considered as an essential preparatory step in root canal treatment sequence. OBJECTIVES: To detect crack formation after coronal flaring of root canals with Gates Glidden (GG) drills, ProTaper Universal (PT) SX, and Endoflare (Ef) flaring instruments using cone beam computed tomography (CBCT) and scanning electron microscope (SEM). MATERIALS AND METHODS: Thirty mesiobuccal canals of mandibular first molars were selected. Teeth specimens were classified into three equal groups according to the instrument used for coronal flaring. Group1: Gates Glidden drills, group 2: ProTaper Universal SX and group 3: Endoflare instruments. Preoperative and postoperative (CBCT) imaging was performed and defect formation was detected. All roots were sectioned horizontally at 2,4and 6 mm from the cementoenamel junction. The sections were inspected under SEM, and any defect formations were recorded and compared with CBCT images according to scoring system. Data were collected and then statistically analyzed at an alpha error of 0.05. P≤0.05 were considered significant. RESULTS: The Ef file produced significantly less dentinal defects compared with the GG and PT SX at the three studied sections. Significant differences were found between the 3 groups at 2 and 4 mm with values (P=0.026) & (P=0.050) respectively, while no significant difference was found at 6mm with value of (P=0.217) when using the 2 evaluation methods. There was a significant difference (P=0.049) between the two used evaluation methods. CONCLUSIONS: Although all used coronal flaring instruments caused dentinal defects, Endoflare file showed the least defects. CBCT was not able to detect the smallest defects such as craze lines while SEM showed more capabilities and was considered as a confirmatory method. KEYWORDS: Coronal flaring, cracks, cone beam computed tomography, scanning electron microscope.