EFFECT OF CHEMICAL AGING ON THE COLOR STABILITY OF TWO CERAMIC MATERIALS; ZIRCONIA REINFORCED LITHIUM SILICATE AND LITHIUM DISILICATS CERAMICS

Abstract

Objectives: The presence of fine-grained crystals of lithium silicate, which contains a high amount of glass provides the material it’s optical and mechanical characteristics. This unique microstructure allows this material to be processed in a dental lab quickly and efficiently in its crystalline state and the exact tooth shade. This study aims to evaluate the color stability of zirconia reinforced lithium silicate ceramic and lithium disilicates ceramic restorations. Materials and Methods: In this in vitro study, 40 discs of 2mm thickness and 10mm in diameter would be fabricated, all samples were divided into two groups (n=20) according to ceramic material used: group Z zirconia reinforced lithium silicates ceramic(ZLS) and group L lithium disilicate ceramic(LS) discs. Each group was subdivided into two subgroups according to the aging process (n=10) (before and after aging). CIELAB color parameters of all samples were calculated from spectral reflectance measurements on a spectrophotometer to evaluate the effect of chemical aging on the color stability. Statistical Analysis: One-way ANOVA analysis was used to compare measurements among groups. Results: ZLS showed lower color stability than LS, and there was a statistical difference between them. Aging affected the color stability of the two ceramics but within an acceptable range with lithium disilicates. Conclusion: ZLS gave lower color stability than LS and aging affected the color stability of both types of ceramic. The postulated hypothecs of this study were ZLS will be higher color stability than LS and chemical aging will have a huge effect.