Methods: 40 acrylic premolar teeth ( Frasaco, #15) were used in the study which were prepared for a full crown preparation. They were then randomly divided into four groups (n=10). For group 1, a thin layer of powder was applied directly onto the surface of the preparation for imaging and optical impression with Cerec Bluecam. For group 2, a sectional impression was made with polyvinylsiloxane (PVS) (3M ESPE Express). The dies were fabricated in stone (GC Fujirock) and the images were made without powdering by Cerec Bluecam. For group 3, a sectional impression was made with PVS, the dies were fabricated in stone and the images were taken without powdering by Cerec InEos Blue Scanner. For group 4, a sectional impression was taken with PVS and lithium disilicate crown copings were produced by conventional methods (control group). The precision of ceramic crowns were examined by measuring the marginal and internal fit of copings by silicon replica technique. The copings were filled with a light body silicone, stabilized with a heavy body material (3M ESPE Express) and the replica samples were examined under light optical microscope.
Results: The marginal and internal fit values of all samples were within clinically acceptable limits. Significant difference was observed in the accuracy of the scanners of the dental CAD/CAM systems. Conventional methods with PVS impression presented the highest marginal and internal fit values (P<.001). Cerec InEos Blue Scanner showed significantly higher precision compared to impressions made with Cerec Bluecam(P<.001).
Conclusions: Optical scanning methods in dental CAD/CAM technologies are precise and reliable methods of digitizing the real-life models, compared to conventinal techniques.