Effects of Different Glaze Treatments on the Optical Properties and Roughness of Lithium Disilicate Ceramics

Objectives: To investigate effects of different glaze procedures on the colour, translucency, and roughness of lithium disilicate (LDS) ceramics after short-term ageing.Materials and Methods: Eighteen LDS specimens (thickness: 0.6 mm) were divided into three groups (paste (EP), spray (ES), and powder–liquid glaze (EL)) based on the type of glaze treatment (n=6). After glaze firings, specimens were thermally aged (5000 cycles). Before and after thermocycling, the colour, translucency, and roughness values of the specimens were measured. Before and after thermocycling, the translucency and roughness data were analysed using a one-way analysis of variance (ANOVA) and compared using a Wilcoxon signed-rank test. Changes in colour, translucency, and roughness data were analysed using one-way ANOVA, and the correlations between them were analysed using Spearman’s correlation analysis (p=.05).Results: The EL group showed the highest and clinically unacceptable colour change value (p≤.005). Before and after ageing, the EL group exhibited higher translucency than the other groups (p<.001), and the EL and EP groups exhibited higher roughness values than the ES group (p≤.001). Wilcoxon signed-rank test results showed that although a significant difference between the initial and final translucency values was observed in the EL group (p=.028), no significant differences between the initial and final roughness values were observed in each group. Only in the EL group, a significant correlation was found between the colour and translucency change values (r=0.943, p=.005).Conclusions: After short-term ageing, based on the evaluation of the LDS ceramics' colour and translucency changes, ES and EP treatments are preferable for glazing. When dentists select a material (EP, EL, ES) for glazing LDS ceramics, they should consider the effects of this material on the optical properties and surface roughness of LDS ceramics