Color Stability and Translucency of Ceramic Laminate Veneer Restoration for Diastema Closure: Effect of Resin Cement Containing Different Photoinitiators

Objectives: To investigate the color stability and translucency of different ceramic laminate veneers for diastema closure bonded with resin cement using different photoinitiating systems based on benzoyl germanium compounds and iodonium salts. Materials and Method: Sixty abutments were milled from a polymethyl methacrylate disc to duplicate a maxillary left central incisor tooth model that had been prepared for laminate veneer restoration. The abutments were devided into six groups (n=10) according to the ceramic type (lithium disilicate, zirconia reinforced lithium silicate, and translucent zirconia) and cement type (Variolink Esthetic LC and RelyX Veneer). Each laminate veneer was bonded to its respective abutment and stored in water for 24 hours. The color coordinates and translucency were analyzed with a reflectance spectrophotometer after cementation and after immersion in coffee solution. The translucency parameters and contrast ratio were measured. The color and the translucency differences were calculated and the data were analyzed (α=.05). The differences in color and translucency were estimated, and the results were statistically assessed (=.05). Results: Ceramic materials showed a significant impact ( P ˂.001) on the color changes after coffee immersion within the Variolink Esthetic LC groups. Ttranslucent zirconia showed the highest color change, followed by zirconia reinforced lithium silicate and lithium disilicate. Among the RelyX Veneer groups, the ceramic materials showed a significant impact ( P ˂.001). Translucent zirconia showed the highest color change, followed by zirconia reinforced lithium silicate and lithium disilicate. The two-way ANOVA test showed a significant interaction in color changes between ceramic type and cement type after cementation ( P =.040), and after coffee immersion ( P =.001). All groups showed a clinically acceptable difference in translucency parameters after coffee immersion. The two-way ANOVA test found a non-significant effect ( P =.151) on translucency changes. Conclusions: Cement selection is important for the color stability and translucency of ceramic laminate veneers after coffee staining. Lithium disilicate veneer is more resistant to coffee staining than zirconia-reinforced lithium silicate and translucent zirconia veneers. Ceramic laminate veneers bonded with resin cement contain benzoyl germanium compounds (Variolink Esthetic LC) are more translucency. However, ceramic laminate veneers bonded using resin cement contain iodonium salts (RelyX Veneer) are more resistant to coffee staining. Clinical relevance: The dentists have to face challenges of predicting the final color of various ceramic laminate veneer restorations used for diastema closure and estimating its color stability after final cementation.