Marginal and Internal Accuracy of CAD/CAM all Ceramic Crowns Fabricated with two Types of Direct Digital Impression Systems (An In Vitro study)

摘要

Direct optical impression system with or without powder opacification are commonly used in fixed prosthodontics, but little information is offered about the effect of the powder parameter on the accuracy of the intra-oral optical scanner. The objective of this present in vitro study was to evaluate the marginal and internal fitness of all ceramic crowns fabricated with direct powder and powder free system (Bluecam camera and Omnicam camera). Twenty four sound upper first premolar teeth of similar size were collected. Standardize preparation of all teeth samples were carried out to receive all ceramic crown restoration with deep chamfer finishing line (1mm), axial length (4mm) and axial convergence (6 degree). All specimens were then divided into two groups according to the type of intra-oral digital impression technique: Group A, Twelve prepared teeth were scanned directly using Omnicam camera; Group B, twelve prepared teeth were scanned directly using Bluecam camera. VITABLOCS MarkII for CEREC/ inlab was used to construct all ceramic crowns for each tooth sample using CEREC MCXL Milling machine. Marginal and internal discrepancy was measured at eight points per tooth using replica technique and stereo- microscope at (120X) magnification. ANOVA and T test post Hoc tests were used to identify and localize the source of difference between the two groups. It was found that there is nonsignificant difference in the marginal and internal gap mean values between (group A and group B). From the above result we can conclude that the two types of intra-oral camera (powder-free Omnicam and powder based Bluecam) have the same accuracy.