Clinical Marginal and Internal Fit of Crowns Fabricated Using Different CAD/CAM Technologies

Purpose The aims of this in vivo investigation were to compare the marginal and internal fit of single-unit crowns fabricated using a selective laser melting (SLM) procedure with two CAD/CAM grinding procedures, and to evaluate the influence of tooth type on the parameters measured. Materials and Methods A total of 270 crowns were evaluated, including 90 SLM metal-ceramic crowns (group B), 90 zirconium-oxide-based ceramic crowns (group L), and 90 lithium disilicate ceramic crowns (group C). The marginal and internal gaps of the crowns were recorded using a replica technique with a silicone indicator paste stabilized with a light-body silicone. The gap replica specimen were sectioned buccolingually and mesiodistally and then examined using a stereomicroscope at 30× magnification. Ten reference points were measured on each anterior and premolar specimen, and 20 reference points were measured on each molar specimen. Two-way ANOVA was performed to identify the significant differences between the groups. Results The mean marginal fit of group B was significantly better than those of group C and group L (p 0.05). The mean axial gap of group B was significantly smaller than those of group C and group L (p 0.05). The mean occlusal gap of group B was significantly higher than those of group C and group L (p 0.05). The marginal and internal gaps of crowns varying according to tooth type were not significantly different (p > 0.05). Conclusion The SLM system demonstrated better marginal and internal fit compared to the two CAD/CAM grinding systems examined. Tooth type did not significantly influence the marginal or internal fit.