Discoloration of flowable and universal resin composites immersed in black tea for 30 days

Abstract

Purpose: This study evaluated the discoloration of current flowable and universal resin composites by immersing in black tea over 30 days. Materials and Methods: Three flowable resin composites and three universal resin composites were evaluated. The composites were inserted into a disk-shaped stainless steel mold and properly cured. The surfaces of the composite disks were wet-ground and ultrasonically cleaned. Colors – L*, a*, and b* were measured at the center of disks on a gray background using a spectrophotometer. The disks were immersed in black tea at 37 ̊C for 30 days, and the colors were repeatedly measured at 1, 3, 5, and 30 days of immersion. Color differences ΔE*ab were calculated from the L*, a*, and b* values. Water sorption and solubility of the composites were also measured as per ISO 4049. The results were statistically analyzed, and regression analyses were done between ΔE*ab and ΔL*, Δa*, Δb* or sorption/solubility. Results: All the composites showed observable increases of ΔE*ab within the first 5 days of immersion. Values of ΔE*ab ranged from 0.64 to 4.97, and three composites exhibited values above the clinically acceptable value, 3.3. ΔL* and Δb* revealed strong correlations with ΔE*ab. Both water sorption and solubility had positive correlations with ΔE*ab at 30 days. Conclusion: Tea immersion induced discoloration of the current resin composites. This discoloration was affected most by the change in brightness and difference in its blue-yellow chromaticity, and the level of discoloration was material dependent. (Asian Pac J Dent 2020; 20: 9-15.)