Abstract
The purpose of this study is to investigate the irradiation-induced color changes of visible light-cured crown and bridge resins and influence of storing conditions on the color changes of resins.
Tristimulus colorimeter was used for color measurment. Disc specimens mearsuring 5.0 mm in diameter and 1. 5 mm in thickness were prepared with enamel, dentin and cervical color paste of each resin. At first, the color changes immediately after irradiation were measured. Then the specimens were stored in 3TC-controlled distilled water or in air. The color at 3 days, and 1, 2, 3 and 4 weeks after irradiation were measured and compared with the color at immediately after irradiation. Color changes were expressed as L*, a* and b* uniform color space (CIE 1976 L* a* b*color difference formula) and total color difference value (ΔEab*, N BS unit) were calculated.
ΔEab* value of each resin between before and immediately after irradiation was large and the difference was assessed as “noticeable” or “much”. This change was attributable mainly to increase in L* and decrease in b*.
With lapse of time, the resins stored in air underwent slight changes in color. By storing in distilled water, L* and b* were decreased and ΔEab* was assessed as “noticeable” or “much”
