Y K Lee1, J M Powers. 1. Department of Dental Biomaterials, College of Dentistry, Seoul National University, Korea.
Abstract
PURPOSE: To determine changes in color and optical properties after polymerization and accelerated aging of white resin-based composites (RBCs) used to restore bleached teeth and compare them with those of conventional shades. MATERIALS AND METHODS: Four white shades and two conventional shades (A2, A3) of two different brands of RBCs (Vitalescence, Synergy) were measured before and after polymerization and after accelerated aging for 150 kJ/m2. Color was measured according to CIE L*a*b* color scale on a reflection spectrophotometer, and scattering coefficient, absorption coefficient, contrast ratio and translucency parameter were calculated. RESULTS: After curing, the color change ( E*) of white RBC was not significantly higher than that of conventional shade (P= 0.05). Color change after curing was positively influenced by the change of K (beta = 0.55), and negatively influenced by the changes of L*, b* and S (beta = -0.34, -0.95 and -0.70, respectively). After aging for 150 kJ/m2, the color changes of white RBCs were 2.4 and 5.8, and those of conventional shade were 1.7 and 2.9, respectively. Higher a* and b* values had a negative influence on the color change for both polymerization and aging.
PURPOSE: To determine changes in color and optical properties after polymerization and accelerated aging of white resin-based composites (RBCs) used to restore bleached teeth and compare them with those of conventional shades. MATERIALS AND METHODS: Four white shades and two conventional shades (A2, A3) of two different brands of RBCs (Vitalescence, Synergy) were measured before and after polymerization and after accelerated aging for 150 kJ/m2. Color was measured according to CIE L*a*b* color scale on a reflection spectrophotometer, and scattering coefficient, absorption coefficient, contrast ratio and translucency parameter were calculated. RESULTS: After curing, the color change ( E*) of white RBC was not significantly higher than that of conventional shade (P= 0.05). Color change after curing was positively influenced by the change of K (beta = 0.55), and negatively influenced by the changes of L*, b* and S (beta = -0.34, -0.95 and -0.70, respectively). After aging for 150 kJ/m2, the color changes of white RBCs were 2.4 and 5.8, and those of conventional shade were 1.7 and 2.9, respectively. Higher a* and b* values had a negative influence on the color change for both polymerization and aging.