The aim of this study was to verify the occurrence of apical deviation and tapering in preparations performed with the use of the standardized technique in mesiobuccal roots of upper molars while varying the type of instruments used (K-type file and Flexofile). After preparation, the roots were made transparent and submitted to examination. The results showed that Flexofile produced a smaller incidence of apical deviation and greater tapering of the root canals
Root canal therapy; Endodontics
