Influence of Composition and Thickness on The Color and Translucency of Glass-Ceramic Materials for Laminate Veneer Restorations: An In Vitro study

Abstract

Statement of the problem: Numerous glass-ceramic materials are commercially available, yet achieving optimal esthetic results relies significantly on material composition and thickness. The selection of suitable material and thickness poses an ongoing challenge in clinical practice. Objective: This study aimed to investigate the effect of the composition and thickness of different glass-ceramic materials on the Commission Internationale de l'éclairage (CIE) L*, a*, and b* color coordinates and the translucency parameter (TP00). Materials & Methods: Glass-ceramic blocks of A2 shade, with low translucency, encompassing feldspathic (FS), leucite-reinforced feldspathic (LR), and lithium-disilicate (LD) compositions, were sectioned into three thicknesses: 0.5 mm, 0.7 mm, and 1 mm (n=10). All specimens were polished with ceramic polishing rubbers. Using a spectrophotometer, the CIE L*, a*, and b* color coordinates of the specimens were measured over gray, white, and black backgrounds. The TP00 was calculated using the CIEDE2000 color difference formula. The CIE L*, a*, b*, and TP00 were analyzed using two-way ANOVA and Tukey HSD post-hoc tests (α=0.05). Results: Material, thickness, and their interaction significantly influenced the CIE L*, a*, b*, and TP00 values (P<0.001). The LR group displayed the highest L* and a* values, while the LD group showed the lowest (P<0.001). Conversely, the LD group exhibited the highest b* value (P<0.001). Lightness was lowest in 0.5 mm-thick specimens (P<0.001) and similar for 0.7 mm-thick and 1.0 mm-thick specimens (P>0.05). Redness and yellowness increased with increasing thickness (P<0.001). Regardless of thickness, the FS group had the highest TP00 (16.32±1.54), while the LR group had the lowest TP00 (14.31±1.67). Regardless of material, 0.5 mm-thick specimens demonstrated significantly higher TP00 (17.49±1.10) than 0.7 mm-thick (15.45±0.83) and 1.0 mm-thick (13.11±1.12) specimens. There was no significant difference between the 0.5 mm-thick FS and LD groups (P>0.05) and 1.0 mm-thick LR and LD groups (P>0.05). Conclusions: Even when sharing the same shade, glass ceramics may exhibit varying color and translucency properties due to their distinct chemical compositions and thicknesses.