The benefit of the operating microscope for access cavity preparation by undergraduate students.

Although studies show the operating microscope (OM) provides benefits for endodontists, the benefit to undergraduates has not been evaluated as completely as for specialists. The purpose of this study was to determine whether using the OM would improve students' performance in endodontic access cavity preparation and canal identification. Thirty-six dental students prepared access cavities and located canals in extracted maxillary molars, before and after training, which varied according to group. The standard group received a lecture and practice in preparation of access cavities. The microscope group received identical instruction using the OM. The control group received lectures only. All groups received equal content and instruction time (2 hr 20 min). Faculty graded preparations according to a multidimensional 5-point rating scale. Using the OM, the microscope group improved significantly in access cavity preparation (p <0.05) and significantly outperformed both standard and control groups in accuracy of identifying canals (p <0.05).