Effect of thickness, cement shade, and coffee thermocycling on the optical properties of zirconia reinforced lithium silicate ceramic

OBJECTIVE: To investigate the effect of thickness, cement shade, and coffee thermocycling (CTC) on the optical properties of zirconia reinforced lithium silicate (ZLS) paired with different shades of a resin cement. MATERIALS AND METHODS: Thirty ZLS specimens were prepared in two different thicknesses (0.8 and 1.5 mm) and three different resin cement shades (Tr, A2, and A3) were applied (n = 5). Color determinations were done before and after 5000 CTC by using a noncontact spectroradiometer. Color change due to CTC and relative translucency parameter (RTP) before and after CTC were calculated by using CIEDE2000. Data were analyzed using ANOVA and Bonferroni‐corrected t‐tests(α = 0.05). RESULTS: Material thickness and resin cement shade (P < 0.001) affected baseline color. Material thickness affected color difference (P = 0.025). Thickness, resin cement shade, and CTC (P ≤ 0.0001) affected RTP. The difference between the color changes of the 0.8‐ and 1.5‐mm specimens combined with A2 shade cement after CTC was significant (P = 0.01). RTPs of all pairs decreased after CTC (P < 0.001). CONCLUSIONS: Cement shade and material thickness affected the baseline color. The thickness of ZLS affected the color change after CTC only with A2 resin cement and the color change was less when the ZLS was thicker. CTC reduced the translucency of all pairs. CLINICAL SIGNIFICANCE: Clinicians and patients should be aware of a potential color change after long‐term coffee consumption when zirconia reinforced lithium silicate is used particularly for laminate veneers with A2 shade of the tested resin cement.