In vitro Study of the Effect of Internal Relief Space on the Color of Ceramic Laminate Veneer

Abstract

BACKGROUND: Ceramic laminate veneer restoring is considered a challenging modality in solving various esthetic dental problems. AIM: The purpose of this study was to investigate the effect of digital internal relief space on the color of ceramic laminate veneer. MATERIALS AND METHODS: An acrylic central incisor model was prepared for ceramic laminate veneer with standard measures. The prepared acrylic resin dentotype model was scanned with intraoral computer-aided design/computer-aided manufacturing (CAD/CAM) optical scanner (CEREC Omnicam|Dentsply Sirona). The laminate veneer design was planned on the optically scanned preparation on CAD/CAM system software (CEREC software|Dentsply Sirona). Thirty ceramic laminate veneer specimens were machined from zirconia-reinforced lithium silicate (Celtra Duo blocks, Dentsply/Sirona) according to standard design by CAD/CAM system with the change of the digital internal relief space settings. The specimens were divided into three groups according to their digital internal relief settings (IRS) (20, 60, and 100 μm) (n = 10). Thirty epoxy dies were duplicated from the prepared acrylic model. The ceramic laminate veneer specimens were cemented to epoxy dies with total etch resin cement system according to the manufacture instructions. The color change (ΔE) of the cemented ceramic laminate veneer specimens was measured by spectrophotometer (Vita Easy shade, Ivoclar Vivadent AG, Schaan, Liechtenstein) using the CIELAB scale and L*, a*, b*. Each specimen was measured two times (before and after cementation). The value of color difference (ΔE) was calculated according to the formula: ΔE = [(L*2 - L*1)2 + (a*2 - a*1)2 + (b*2- b*1) 2]½. RESULTS: The highest mean value of ΔE was recorded in G100 group (1.91 ± 0.33), followed by G60 group (1.83 ± 0.09), with the least value recorded in G20 group (1.49 ± 0.49). Analysis of variance test revealed a statistically significant difference between groups (p = 0.024). CONCLUSION: The change of the digital IRS affects the color of ceramic laminate veneers.