What is the Impact of Impression Techniques on the Marginal Adaptation of Metal-Ceramic Crowns Fabricated by Direct Metal Laser-Sintering

Introduction: Studies on Marginal adaptation of restorations fabricated by direct metal laser-sintering DMLS are limited. This study to evaluate the effect of two impression techniques on the marginal adaptation of metal ceramic crowns fabricated by DMLS. Materials and Methods: Twenty intact maxillary premolars extracted for orthodontics reasons were received metal-ceramic crowns. After preparation according to the preparation guidelines for metal-ceramic crowns, the teeth were divided into two groups according to impression techniques (n=10): (1) group A IOS impression, (2) group B conventional impression. Group A specimens were scanned using IOS (I 500, MEDIT, Korea). Whereas, a custom-made tray used to make putty-wash impression to the specimens of group B. Group B casts were scanned using extraoral scanner (Identica T300, META, Korea). The metal coping designs were transferred to a direct metal laser-sintering (MYSINT100, SISMA, Italy), and they were made from Co-Cr blocks. The marginal adaptation was measured at labial, palatal, misael, and distal surfaces using microscope (Olympus, Japan). Student’s paired t test was used to assess the marginal adaptation between the groups. The cutoff value for statistical significance was set at α = 0.05. Results: A statistically significant differences in marginal adaptation was found between the impression techniques for all evaluations (labial, palatal, misael, and distal) (P<0.05). The lowest values were recorded with IOS impression in all surfaces. Conclusions: the marginal adaptation values of IOS impression exhibited an acceptable marginal fit of less than 120 μm