RESUMEN
INTRODUCTION: The removal of dentin interferences from the cervical third of root canals is essential for their correct cleaning and shaping and to facilitate access of endodontic instruments to the critical apical region. In mandibular molars, the concavity observed in the furcation area reduces dentin thickness, making this region more susceptible to perforation. The present ex vivo study used cone-beam computed tomographic imaging to compare 3 rotary burs with a new rotary bur recently launched in Brazil (ie, CPdrill; Helse Industry and Commerce Ltda, Santa Rosa, São Paulo, Brazil) regarding the amount of dentin removal from the distal wall of the mesial root of mandibular first molars. METHODS: A total of 40 root canals were selected and randomly divided into 4 groups for cervical preparation: Gates-Glidden burs #2 and #3 (Dentsply Maillefer, Ballaigues, Switzerland), Largo burs #1 and #2 (Dentsply Maillefer), LA-Axxess burs #1 and #2 (SybronEndo, Glendora, CA), and CPdrill burs (1-size only). Dentin thickness in the distal wall of mesial canals at 2 mm from the furcation was measured using I-CATvision software before and after cervical preparation. RESULTS: There was no statistically significant difference between groups regarding residual dentin thickness after instrumentation with the drills (P = .684). CONCLUSIONS: It was concluded that CPdrill is safe for use in cervical preparation of the mesial root of mandibular first molars because it did not promote excessive dentin removal on distal walls.