Effect of Gates Glidden, La Axxess, SX and ultrasound on the circularity and area of mesial canals of mandibular molars

Introduction: Biomechanical preparation must provide a taper shape at crown-apex direction for root canal resulting in adequate space for irrigation and enabling an effective obturation. However, this stage requires a cervical preparation aiming to remove the interferences to make the access to the apical portion easy for instrumentation. Objective: To evaluate in vitro the effect of coronal flaring on the root canal area and in the circularity of mesial canals of lower molars after using Gates Glidden, La Axxess, Sx file or a ultrasonic TU-24tip. Material and methods: Twenty-four lower molars had their roots embedded into acrylic resin. Then the roots were sectioned horizontally at 2 mm below the cementenamel junction. The sections were photographed before and after the different coronal flaring. All images were analyzed using Image J software to calculate the root canal area and the circularity of the root canal. One-way Anova was used to compare the circularity among the groups, while Kruskal-Wallis test was used for comparing the areas. A Pearson test was used to correlate root canal area and circularity data. Results: There was no significant difference among the groups neither for the circularity (p > 0.05) nor for the