Effect of high-speed sintering on the marginal and internal fit of CAD/CAM-fabricated monolithic zirconia crowns

This study compared the marginal and internal fit of zirconia crowns fabricated using conventional and high-speed induction sintering. A typodont mandibular right first molar was prepared and 60 zirconia crowns were fabricated: 30 crowns using conventional sintering and 30 crowns using high-speed sintering. We presented a new evaluation methodology to measure the marginal and internal fit of restorations through digital scanning, aligning the two datasets, and measuring the distance between two arbitrary point sets of the datasets. For the marginal fit, we calculated the maximum values of the shortest distances between the marginal line of the prepared tooth and that of the crown. The calculated values ranged from 359 to 444 mu m, with smaller values for the high-speed sintered crowns (P<0.05). For the internal fit, we employed mesh sampling and computed the geodesic distances between the prepared tooth surface and the crown intaglio surface. The measured values ranged from 177 to 229 mu m with smaller values for the high-speed sintered crowns, but no significant difference was found (P>0.05). Based on our results, the high-speed sintering method can be considered a promising option for single-visit zirconia treatment in dental practice.