Effect of different rotary instruments on crack formation after coronal preflaring of root dentin

Introduction: The aim of the present study was to investigate the incidence of cracks in root dentin after coronal flaring using various coronal preflaring instruments such as Gates Glidden drills (Mani, Japan), ProTaper Universal SX (Dentsply, Switzerland), K3 (Sybron Endo, USA), Endoflare (MicroMega, France). Materials and Methods: Fifty freshly extracted single-rooted teeth with single canal were collected. All the teeth were randomly divided into five groups of ten each, of which one group served as Control and rest of the four groups were instrumented with Gates Glidden drills, ProTaper Universal (SX), K3 instrument, and Endoflare, respectively. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, and 5 mm from the cementoenamel junction and examined under a stereomicroscope at 10 magnification. Any crack formations were recorded. The data were analyzed using Chi-square test. Results: The Gates Glidden drills resulted in a higher rate of crack formation in root dentin ( P P > 0.05) while preflaring of canal orifices. Conclusions: The use of the Gates Glidden drills resulted in more crack formation. However, the results for the ProTaper Universal, Endoflare, and K3 flaring instruments were less in terms of crack formation.