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Comperative Evaluation of the Translucency of Different CAD/CAM Materials
Comperative Evaluation of the Translucency of Different CAD/CAM Materials Mine Helvacıoğlu Özkardeş, Erkut Kahramanoğlu Marmara University, Faculty of Dentistry, Department of Prosthodontics, İstanbul, TURKEY Objective: The purpose of this study was to evaluate the optical properties of novel cubic ultra high-translucent (UHT) zirconia with lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) glass-ceramic for the manufacture of monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) anterior crowns. Materials and Methods: The ultrahigh-translucency UHT zirconia, high-translucency grade ZLS and the low-translucency grade L-DIS were milled. Twenty-four monolithic crowns were made from 1 CAD file, corresponding to thickness 1.5 mm, and subdivided (n=8) into 3 groups: UHT zirconia, ZLS and LDS. All Groups were shaded using A1 color standard. Translucency of the crowns was measured by contrast ratio using a dental spectrophotometer applied to the labial surface of the crowns over black and white background. Data were analyzed using the 1-way ANOVA and the Tukey HSD test (a=.05). Results: The mean contrast ratios of UHT zirconia, LDS, ZLS specimens were 0,39 (0,02), 0,42 (0,03) and 0,42 (0,02), respectively. UHT zirconia has significantly lower CR compared to LDS and ZLS, whereas there was no significant differences were noted between LDS and ZLS. In this study, novel translucent zirconia (GC Initial UHT) showed more translucency than lithium disilicate (IPS e.max) and zirconia-reinforced lithium silicate (Celtra Duo) ceramics. Conclusions: To obtain esthetic restorations and provide shade matching with natural dentition especially for anterior teeth, monolithic materials should be carefully chosen. The optical properties of monolithic restorative materials were influenced by the type of the material used. Zirconia translucency was improved by eliminating the tetragonal phase, which is responsible for the toughening effect; thus, further studies are advocated to investigate the mechanical resistance of cubic zirconia. Keywords: Esthetic dentistry, monolithic materials, translucent zirconia, CAD/CAM.