comparing the coronal flaring efficacy of five different instruments using cone-beam computed tomography

introduction: fearless removal of tooth structure during canal preparation and shaping has negative effects on the prognosis of treatment. on the other hand, sufficient pre-enlargement facilitates exact measurement of the apical size. the present in vitro study aimed to compare the efficacy of gates-glidden drills, k3, protaper, flexmaster and race instruments in dentin removal during coronal flaring using cone-beam computed tomography (cbct). methods and materials: a total of 40 mandibular molars were selected and the coronal areas of their mesiobuccal and mesiolingual root canals were randomly prepared with either mentioned instruments. pre- and post-instrumentation cbct images were taken and the thickness of canal walls was measured in 1.5- and 3-mm distances from the furcation area. data were analyzed using the one-way anova. tukey’s post hoc tests were used for two-by-two comparisons. results: at 1.5-mm distance, there was no significant difference between different instruments. however, at 3-mm distances, gates-glidden drills removed significantly more dentin compared to flexmaster files (mean=0.18 mm) ( p <0.02); however, two-by-two comparisons did not reveal any significant differences between the other groups. conclusion: all tested instruments can be effectively used in clinical settings for coronal pre-enlargement.