Study on Change of Water Resistance Due to Deterioration of Light-cured Glazing Agents Applied on Indirect Composite Resin

Objectives: Light-cured glazing agents were developed for the purpose of improvement of the surface glazing and wear resistance on denture base resin, then were also applied on direct or indirect composite resin. The purpose of this study is to clarify the water resistance of light-cured glazing agents applied on indirect composite resins.
Methods: Five light-cured indirect composite resins (CERAMAGE; SHOFU, GRADIA; GC, ESTENIA C&B; KURARAY NORITAKE DENTAL, CERAMAGE DUO; SHOFU, GRADIA FORTE; GC) were used in this study. Furthermore, five light-cured glazing agents (RESIN GLAZE Liquid; SHOFU, NANOCOAT Lab; GC, SURFACE CORT; KURARAY NORITAKE DENTAL, Palaseal; Heraeus, BISCOVER LV; BISCO) were applied on these indirect composite resins. After each indirect composite resin paste was filled in a Teflon mold (10×20×1 mm), the sample was light-cured for 15 min per one surface, then whole surface was polished with #400 SiC paper. After every light-cured glazing agent was applied on whole surface of specimens, light curing for 5 min per one surface was performed. Water absorptions and contact angles of water were measured after the immersion test in water (0 to 8w), the thermal shock test conducted at 5 and 60°C (2,000, 5,000, 10,000 cycles) and the accelerated deterioration test. Contact angles were measured using by wetting property evaluation apparatus (LSE-ME3，Nick). The 3-way ANOVA and Tukey’s multiple comparisons were performed.
Results: Water absorptions increased as the immersion period in water, the number of thermal shock cycles, and the accelerated deterioration time increased. The contact angle of water decreased as the immersion period increased, but the thermal shock test and accelerated deterioration test showed different changes.
Conclusions: Through all the tests, it was found that the water absorption and the contact angle of water differ depends on the type of indirect composite resin and the type of light-cured glazing agents.