Discoloration of dental resin composites after immersion in a series of organic and chemical solutions.

The objective of this study was to evaluate the color change of dental resin composites following a series of immersion treatments, especially in organic substances. The color of four resin composites was measured according to the CIELAB color scale relative to the standard illuminant D65. Color was measured at baseline, and after sequential immersion in the following substances: Step 1, porcine-liver esterase (a substitute for a salivary esterase); Step 2, organic substances (mucin and serum) and phosphate-buffered saline (PBS) as a control; Step 3, chemical alteration agents [chlorhexidine (CH) and carbamide peroxide (CP)]; and Step 4, 2% methylene blue. Porcine-liver esterase caused color changes (DeltaE(ab) (*)) of 0.7-1.1 from the baseline. Organic substances caused color changes of 0.4-1.8 from the baseline, and color changes in organic substances were not significantly higher than those in PBS (p > 0.05), except for one composite. Combined treatment with mucin (or serum) with CH (or CP) did not produce significantly higher color changes compared to controls (p > 0.05). Mucin-treated composites showed generally lower methylene blue staining compared to serum and PBS groups. Although combined treatment of organic substances and chemical agents resulted in various discolorations of resin composites, chemical alteration of organic substances did not produce higher color change compared to PBS controls.