Color stability, Roughness, and Microhardness of Enamel and Composites Submitted to Staining/Bleaching Cycles
Sarah S. Al‐Angari, George J. Eckert, Alaa H.A. Sabrah
Abstract
OBJECTIVE: To compare the effect of two bleaching systems (bleaching gel and whitening strips) on the color change, roughness, and microhardness of enamel and two resin composites. MATERIAL AND METHODS: ) were measured using a spectrophotometer, optical profilometer, and Vickers microhardness (VHN) tester, respectively. The specimens were stained with coffee for 14 days, and randomized into two bleaching groups: gel and strips (n = 8), then submitted to a 10-day bleaching/staining test. Color, roughness, and microhardness were re-measured. The outcomes were analyzed using two-way ANOVA and Fisher's-PLSD test (α = 0.05). RESULTS: Gel significantly improved the color (ΔE 4.9-8.3) and increased the roughness (Ra 0.04-0.08 μm) of all substrates (p < 0.0001) compared to strips. Enamel color was significantly improved (ΔE 5.4-8.3) compared to that of HU (ΔE 2.6-4.9) and TS (ΔE 2.0-4.9) with either gels or strips. TS roughness (0.03-0.08 μm) was significantly higher than that of enamel (0.01-0.05 μm) and HU (0.02-0.04 μm). Enamel had significantly reduced microhardness compared to HU (p = 0.0144). CONCLUSION: Gels produced the greatest color improvement and roughness compared to strips. Enamel had significant color improvement but had the greatest decrease in microhardness. CLINICAL SIGNIFICANCE: There was unacceptable color change between enamel and the composites after the combined cyclic effects of staining and bleaching.