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

Abstract

Objective: Along with developing technology, digital meth- ods 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 be- fore 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 pro- duced with the DMLS method. The marginal and internal gap was measured twice using the silicone replica technique, before and after the porcelain pro- cesses. Under a stereomicroscope, measurements were made from the mesial, occlusal, and distal surfaces, with 21 measurements from each sam- ple. Statistical analysis was performed and p<0.05 was considered statisti- cally 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 sta- tistically 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 metal- ceramic restorations, whose metal substructures are produced by the DMLS technique, can create marginal and internal discrepancy above clinically ac- ceptable limits.