Abstract: Objective: To evaluate the color and translucency of zirconia and glass ceramic after ultraviolet aging. Methods: Forty-eight specimens (n=12) of high-translucent zirconia, low-translucent zirconia, high-translucent glass-ceramic, and low-translucent glass-ceramic were prepared (1.60±0.02 mm thickness) and polished by 600 mesh emery sandpaper. The L^*a^*b^* color measurements were performed using a spectroradiometer under gray, black, and white background. Color and translucency values of the specimens before and after ultraviolet aging (λ=253.7 nm, 250 w/m²) for 12h and 24h were evaluated. Color changes (ΔE) were considered to be visually perceptible when ΔE > 1.0 and clinically acceptable when ΔE<3.3. Results: After ultraviolet aging for 12h and 24h, ΔE of high-translucent zirconia were (3.33±0.78) and (6.00±0.84), ΔE of low-translucent zirconia were (1.53±0.42) and (3.45±0.40), respectively. These color changes were visually perceptible with clinical significance (ΔE＞1.0), and the color change of high-translucent zirconia was more prominent than that of low-translucent zirconia (P<0.05). The ΔE of high-translucent and low-translucent glass-ceramics after ultraviolet aging were less than 1.0 and visually imperceptible. The translucencies of 4 ceramics decreased significantly after ultraviolet aging for 12 h and 24 h (P<0.05). The translucency changes of high-translucent zirconia were (-3.62±0.76) after ultraviolet aging for 12 h and (-4.59±0.75) after ultraviolet aging for 24 h, which were significantly remarkable than those of other 3 ceramics (P<0.05). Conclusion: The color change of high-translucent zirconia after ultraviolet aging exceeded the clinically acceptable level, and the translucency of it decreased significantly. The color and translucency of low-translucent zirconia and both glass-ceramics were less affected by ultraviolet aging.

Key words: zirconia, ceramics, ultraviolet, aging