Effects of restorative material, intraoral scanner, and digital workflow on the marginal and internal fit of CAD-CAM all-ceramic crowns: an in vitro study

PURPOSE. This study evaluated the marginal and internal fit of CAD-CAM all-ceramic crowns fabricated from a polymer-infiltrated ceramic network material (PICN; VITA Enamic®) and a zirconia-reinforced lithium silicate ceramic (ZLS; VITA Suprinity® PC). In addition, the effects of intraoral scanner type and chairside versus labside digital workflows were assessed. MATERIALS AND METHODS. Crowns were fabricated in two experimental series. In series 1, CEREC Bluecam AC and CEREC Omnicam AC intraoral scanners were compared. In series 2, chairside and labside digital workflows were evaluated. In both series, PICN and ZLS crowns were investigated. Marginal fit was assessed using reflected light microscopy and the replica technique, whereas internal fit was assessed using the replica technique. Data were analyzed using rank-based two-factor analyses and correlation analyses. RESULTS. In series 1, scanner type did not significantly affect marginal fit, whereas Bluecam demonstrated smaller internal gaps than Omnicam (P = .0059). PICN crowns exhibited smaller marginal gaps than ZLS crowns in both series (P < .0001). For internal fit, restorative material had a significant effect in series 1 (P = .0003), but not in series 2 (P = .4376). In series 2, the chairside workflow resulted in smaller marginal gaps when assessed by reflected light microscopy (P = .0064) and smaller internal gaps when assessed by the replica technique (P = .0288), whereas no workflow-related difference was observed for marginal fit measured with the replica technique (P = .1496). Significant material-dependent interaction effects were identified. Marginal gap values obtained by reflected light microscopy and the replica technique showed significant positive correlations. CONCLUSION. Marginal and internal fit were influenced by restorative material, scanner type, measurement method, and specific interaction effects. Series 2 findings should be interpreted as differences between the chairside and labside workflows as performed in this study rather than as effects of the digitization step alone.