Clinical internal and marginal fit of metal-ceramic fixed dental prostheses fabricated with selective laser melting and 3D-printed pattern casting using cobalt-chromium metal alloy

Purpose: To evaluate the fit of metal-ceramic three-unit fixed dental prostheses (FDPs) fabricated using selective laser melting (SLM) and 3D-printed casting pattern (CP) and to compare the effect of tooth type and ceramic veneering on marginal and internal gaps. Materials and Methods: Patients requiring posterior three-unit FDPs were selected. For each subject, two FDPs were fabricated using SLM and CP. Silicon replica was used to measure the internal and marginal fit of frameworks before and after ceramic veneering. For each replica, 36 measurements were performed using a stereomicroscope: 4 marginal and 32 internal (4 deep chamfers, 12 axial, 4 axio-occlusal, and 12 occlusal). Statistical analysis was performed using two-way ANOVA and paired t-test. Results: A total of 44 metal-ceramic FDPs were fabricated in 22 patients. The results showed that the fabrication method had no significant effect on the marginal, deep chamfer, or occlusal gaps. However, the method significantly affected the axial, axioocclusal, and total internal fit, and the SLM had larger gaps than the CP. For the effect of ceramic veneering, measurements were significantly higher in the CP group at all gaps, except for the premolar axial and molar occlusal gaps. The SLM fit was less affected by ceramic veneering. Only premolar gaps significantly increased at the marginal, deep chamfer, and axial and axio-occlusal positions. Conclusion: Metal-ceramic FDPs fabricated using SLM and CP techniques provided a similar marginal fit. Premolars had smaller discrepancies compared to molars. The ceramic veneering process increased the gap of the prostheses, with SLM being less affected by ceramic veneering.