Objective: This study compared the opaque characteristics of light-cured composite resins and attached shade guides.
Methods: Three kinds of light-cured composite resins and attached shads guides were used. A plastic mold (10mm in diameter and 4mm in height) was used to prepare disk specimens. Color was measured by CIE L*a*b* relative to CIE source against a white and a black background, using a colorimeter. Color change (DeltaE)was calculated as DeltaE=[(DeltaL*)(2)+(Deltaa*)(2)+(Deltab*)(2)](1/2). The heights of composite resins were recorded as DeltaE is approximately 1.5. The infinity optical thickness of composite resins when delta E*=1.5 was calculated by regression formulation.
Results: There was significant difference in color difference and the infinity optical thickness among materials and shades. The infinity optical thickness gradual decreased in the same shade mark from 1 to 4, and from A to D the results was not simple.
Conclusion: There was significant difference in the infinity optical thickness between the attached shade guides and the resins materials. Composite resins contain micro-filler were inferior in infinity optical thickness.