Comparison of Fit Between Zirconia and Metal Copings Fabricated Conventionally or Using Different CAD/CAM Techniques

This study was designed to assess the fit of cobalt chromium copings fabricated using direct metal laser sintering and to compare with copings fabricated from nickel chromium (traditional casting) and zirconia (milled from partially sintered blanks). For both cobalt chromium and zirconia groups, impressions were generated using direct or indirect digitization. There were 5 experimental groups of 12 copings fabricated for a prepared maxillary right molar. The intimacy of fit (measured at the margin, axial wall and occlusal) was assessed using a replica method technique. The results showed that zirconia copings produced using direct digitization had significantly smaller marginal, axial and occlusal measurements compared to other groups (p⟨0.05). Nevertheless, all groups had a mean marginal gap within accepted clinical values. Though there was a decrease in the intimacy of fit from the margin to axial wall to the occlusal surface. It can be concluded that the fit of zirconia copings fabricated using direct digitization was significantly better than the other groups. However, it can be expected that further enhancement and refinement of additive technology such as direct metal laser sintering will offer clinicians a viable alternative to nickel chromium analogue production methods in the future.