Comparative evaluation of the marginal fit and thickness of cobalt-chromium metal copings fabricated using CAD/CAM and direct metal laser sintering – an invitro study

Objective: To evaluate and compare the marginal fit and thickness of cobalt-chromium (Co-Cr) metal copings fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) milling and direct metal laser sintering (DMLS) techniques. Materials and Methods: A standardized typodont molar tooth was prepared and scanned to obtain a digital model using CAD software. Thirty-two Co-Cr copings were fabricated and divided into two groups: Group I (n = 16) – CAD/CAM-milled copings, and Group II (n = 16) – DMLS-fabricated copings. Marginal fit was evaluated under a stereomicroscope at four predetermined sites (mid-buccal, mid-palatal, mid-mesial, mid-distal). Thickness was measured using a thickness gauge at the same sites. Data were analyzed using independent t-tests with a significance level of p < 0.05. Results: DMLS copings exhibited significantly superior marginal fit compared to CAD/CAM copings (p < 0.05). The mean marginal gap values in the DMLS group ranged between 52.6–80.5 μm, while CAD/CAM copings ranged between 74.3–99.8 μm. Thickness values showed greater uniformity in DMLS copings, with statistically significant differences between the two groups across all sites (p < 0.0001). Conclusion: Within the limitations of this in vitro study, DMLS-fabricated Co-Cr copings demonstrated better marginal adaptation and more consistent thickness compared to CAD/CAM-milled copings. These findings suggest that DMLS may provide enhanced clinical outcomes in fixed prosthodontic restorations.