Evaluation of Marginal and Internal Fit of Metal-Ceramic Restorations Produced by Direct Metal Laser SinteringMethod Before and After Porcelain Application: Experimental Study (In Vitro Material Study)

Objective: Along with developing technology, digital methods have begun being used for the production of metal-ceramic systems. However, there are very few studies that investigate the changes of the marginal discrepancy during porcelain processes. The aim of the study is to compare the marginal discrepancy of metal-ceramic restorations produced by the direct metal laser sintering (DMLS) method using metal powders before and after the porcelain applying process. Material and Methods: A four-unit fixed restoration was designed at the right maxilla between the first premolar and second molar teeth. A total of 10 restorations were produced with the DMLS method. The marginal and internal gap was measured twice using the silicone replica technique, before and after the porcelain processes. Under a stereomicroscope, measurements were made from the mesial, occlusal, and distal surfaces, with 21 measurements from each sample. Statistical analysis was performed and p<0.05 was considered statistically significant. Result: At the molar tooth, a statistically significant increase in marginal discrepancy was observed at the mesial region (p<0.001) and at the occlusal region (p<0.001). At the premolar tooth, a statistically significant decrease in marginal discrepancy was observed at the mesial region (p<0.001), and an increase was observed at the occlusal region (p<0.001). Conclusion: The results of our study; It shows that 4-units metalceramic restorations, whose metal substructures are produced by the DMLS technique, can create marginal and internal discrepancy above clinically acceptable limits.