Effect of abutment tooth color, cement color and thickness and ceramic thickness on final color of glass ceramic lithium disilicate restorations

Abstract

Introduction: The optical properties of the natural teeth are the result of the reflection and diffusion of enamel and dentin through tooth structure. Matching the optical properties of dental restoration with natural teeth is a major challenge in dentistry. The aim of this study was to determine the effect of abutment tooth color, color and thickness of cement and ceramic on the final color of ceramic lithium disilicates. Materials and Methods: E.max CAD blocks in three colors (A1, A2, A3) of and 2 translucencies (HT, MT) were used for the preparation of 120 disk shapes samples in three thicknesses (1 mm, 1.5 mm, 2 mm) with dimensions of 12*14 (N=10) . Foundation blocks were made of base metal alloy and natural die materials (ND1, ND2, ND3, ND4, ND5, ND6, ND7, ND8, ND9). The color coordinates CIE-L * a * b * were calculated for each color in the form of the CIE coordinate values (L *, a *, b *). The color difference of each ceramic-cement-block assembly with the control block (ΔE) was calculated from the average of 50 times (repeated 5 times for each set). Results: The final color of the ceramic with 0.1 mm thickness of cement, was significantly affected by the color of the tooth, color of the ceramic, ceramic thickness and type of the cement. In 0.2 mm thickness of the cement the final color of ceramic restorations was significantly affected by the ceramic color, ceramic thickness along with the type of cement. Conclusion: The color of the abutment tooth and ceramic, ceramic thickness and type of cement in 0.1 mm sections and ceramic color, ceramic thickness and cement type in 0.2 mm sections significantly affected the final color of restorations. Also, changing the color of the tooth base from light to dark will result in an increase in  values.