CAD/CAM applications for implant-supported prosthesis

Introduction: The integration of CAD/CAM technology with high-strength ceramics enables the creation of all-ceramic restorations, even in posterior regions. These restorations are typically composed entirely of ceramic material. Alternatively, a high-strength ceramic substructure can be utilized, necessitating ceramic veneering and glazing. CAD/CAM milling techniques, along with the advent of new zirconia ceramics, facilitate the production of full-zirconia restorations featuring occlusal design, without the need for veneering. Aim of the Study: The aim of the study is to assess the abrasion of zirconia restorations in comparison to ceramic ones, and also to evaluate the abrasion of the opposing teeth to these restorations. Material and Methods: The specimens, totaling 16 in number with a diameter of 5mm and a thickness of 2mm, were crafted from various ceramic materials. The zirconia specimen underwent glazing immediately after polishing. Ceramic veneers were chosen to be applied onto the zirconia substructures. Human enamel and Vita Omega 900 ceramic, typically utilized in metal-ceramic restorations, served as reference materials. The ceramic veneers were glazed using the appropriate glazing material. The specimens were then smoothed using abrasive paper while being cooled with cold water. Surface roughness was assessed before conducting the abrasion tests using a profilometer. Standard abrasion simulation was achieved using steatite spheres as antagonists. Results and Discussions: Zirconia demonstrates greater resistance to abrasion compared to ceramic materials. Interestingly, in the subsequent analysis, the hypothesis suggesting that the reduced abrasion observed for zirconia would coincide with increased abrasion of antagonists was disproved. Although enamel antagonists were not quantitatively assessed, comparison of SEM micrographs revealed similar wear patterns for both steatite and enamel. The materials tested represent typical zirconia ceramics commonly employed in the fabrication of all-ceramic substructures. Conclusions: The abrasion tests conducted with steatite or enamel antagonists did not reveal any noticeable abrasion on the surface of zirconium oxide. Ceramic exhibited comparable or even lower rates of abrasion compared to enamel. The abrasion experienced by antagonists against zirconia was found to be similar or even lower when compared to the results observed with ceramic.