Influence of curing light irradiance and ceramic thickness on color stability and translucency of cemented ceramic laminate veneers

This in vitro study aimed to evaluate the effects of curing light irradiance and ceramic thickness on the color stability and translucency of cemented laminate veneers after accelerated aging. Eighty ceramic disks were fabricated using shade A3 IPS e.max Press HT specimens of 0.50-mm and 1.00-mm thickness. Specimens of each thickness were randomly divided into four groups, and the A3 shade of Variolink N resin cement was used for bonding in three groups with light irradiances of 700 mW/cm², 900 mW/cm², and 1100 mW/cm². The CIE L*a*b* parameters were measured before and after 5,000 thermal cycles of 5 °C and 55 °C. Changes in the color and translucency were measured through spectrophotometry and analyzed using two-way analysis of variance. Results both ceramic thickness and curing light irradiance caused statistically significant differences in color after aging (P < 0.01). The greatest color changes were observed in samples of thickness 0.50 mm that received a light irradiance of 700 mW/cm². Samples with varying thicknesses and curing light irradiances showed statistically significant differences in the extent of decrease in translucency after aging (P < 0.01). The results of this study demonstrated that cemented ceramic laminate veneers tended to become darker and yellower after aging. The light irradiance and ceramic thickness clearly affected the color stability of the veneers. The translucency of the veneers was significantly related to their thickness, and aging clearly decreased the translucency of the veneers.