Assessment of Teeth Prepared by Senior Dental Students for CAD/CAM Restorations

The aim of this study was to evaluate teeth prepared for computer-aided design/computer-aided manufacturing (CAD/CAM) restorations by senior dental students using recently developed rubrics. The rubrics used evaluation criteria based on four factors: retention or resistance form; marginal or internal adaption or manufacturing process; biology, esthetics, or durability of restorative material; and intraoral scanner impression. In academic year 2018-19, four faculty members used the rubrics to assess 111 first maxillary right premolars (tooth no. 4) prepared for lithium disilicate crowns and 223 second maxillary right premolars (tooth no. 5) and first maxillary right molars (tooth no. 3) prepared for monolithic zirconia partial fixed dental prostheses. The preparations had been performed on typodont teeth. The most common errors identified for tooth preparations were in the finish line quality (136 errors in 223 prostheses), a criterion that is crucial for quality CAD/CAM restorations. To prevent poorly fit CAD/CAM restoration preparations that result from an unacceptable finish line quality, students need to understand the rationale used to develop detailed rubrics and adhere to the defined critera.