Clinical marginal and internal fit of metal ceramic crowns fabricated with a selective laser melting technology.

STATEMENT OF PROBLEM: Selective laser melting (SLM) technology has been introduced to fabricate dental restorations. However, the fit of these restorations still needs further study. PURPOSE: The purpose of this in vivo investigation was to compare the marginal and internal fit of SLM metal ceramic crowns with 2 lost-wax cast metal ceramic crowns and to evaluate the influence of tooth type on the marginal and internal fit of these crowns. MATERIAL AND METHODS: A total of 330 metal ceramic crowns were evaluated. The metal copings were fabricated with SLM Co-Cr, cast Au-Pt, and cast Co-Cr alloy (n=110). The marginal and internal gaps of crowns were recorded by using a replica technique. The anterior and premolar replicas were sectioned 2 times, and molar replicas were sectioned 4 times. The marginal and internal gap width of each cross section was examined by stereomicroscope at x30 magnification. Two-way analysis of variance was performed to identify the statistical difference among the groups. RESULTS: The marginal fit of the SLM Co-Cr group (75.6 +/-32.6 mum) was not different from the cast Au-Pt group (76.8 +/-32.1 mum) (P>.05) but was better than the cast Co-Cr group (91.0 +/-36.3 mum) (P<.01). No significant difference was found among the SLM Co-Cr group (127.3 +/-45.8 mum), cast Au-Pt group (129.9 +/-61.1 mum). and cast Co-Cr group (142.5 +/-63.7 mum) (P>.05). The mean occlusal gap width of the SLM Co-Cr group (309.8 +/-106.6 mum) was significantly higher than that of the cast Au-Pt group (254.6 +/-109.6 mum) and the cast Co-Cr group (249.6 +/-110.4 mum) (P<.005). No significant difference was found in the marginal fit among the anterior group (84.4 +/-35.1 mum), the premolar group (80.6 +/-26.3 mum), and the molar group (82.7 +/-38.0 mum) (P>.05). Also, no significant difference was found in the axial fit among the anterior group (138.3 +/-52.5 mum), the premolar group (132.9 +/-50.4 mum), and the molar group (134.4 +/-52.5 mum) (P>.05). The anterior group (267.6 +/-110.2 mum) did not differ from the premolar group (270.2 +/-112.8 mum) and the molar group (268.6 +/-110.5 mum) in occlusal fit (P>.05). CONCLUSIONS: The marginal fit of SLM Co-Cr metal ceramic crowns was similar to that of the cast Au-Pt metal ceramic crowns and was better than that of the cast Co-Cr metal ceramic crowns. The SLM Co-Cr metal ceramic crowns were not significantly different from the 2 cast metal ceramic crowns in axial fit but were less accurate in occlusal fit. Tooth type did not influence the marginal and internal fit of the metal ceramic crowns.