Combined effect of staining substances on the discoloration of esthetic Class V dental restorative materials.

The purpose of this study was to determine the combined effect of an organic substance (mucin as a substitute for salivary organic substances), chlorhexidine, and an iron compound/tea solution on the changes in the color of esthetic Class V dental restorative materials. Color of a glass ionomer, resin-modified glass ionomer, compomer and flowable resin composite of A2 shade, respectively, was determined 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, mucin in PBS (MCP) for 48 h; Step-2, chlorhexidine (CHX) for 24 h; Step-3, iron compound (IRN) or tea solution (TEA) up to 7 days; and Step-4, ultrasonic cleaning for 1 h. Color change (DeltaE(ab )*) was calculated by the equation: DeltaE(ab)* = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2), of which DeltaL(*) indicates changes in value, Deltaa(*) indicates changes in red-green parameter and Deltab(*) indicates changes in yellow-blue parameter. DeltaE(ab)* values after immersion in MCP and CHX were compared, and DeltaE(ab)* values after immersion in IRN or TEA, and subsequent ultrasonic cleaning were compared with respect to the restorative material and immersion substance. DeltaE(ab)* and changes in the color parameters (DeltaL(*), DeltaC(ab)* and DeltaH(ab)*) were analyzed by repeated measures, analysis of variance and a post-hoc test at the 0.05 level of significance. Color changes after immersion in MCP were acceptable (DeltaE(ab)* < 3.3), and those after immersion in CHX were generally acceptable. The range of DeltaE(ab)* values after immersion in IRN was 3.1-19.6, and that after ultrasonic cleaning was 2.4-9.6. The range of DeltaE(ab)* values after immersion in TEA was 10.7-21.1, and that after ultrasonic cleaning was 11.9-14.5. Color changes of four Class V restorative materials after combined treatment with mucin, chlorhexidine and an iron compound/tea solution were not acceptable. Colors did not recover to their original values after ultrasonic cleaning. Modifications on the surface of a restoration should be considered to reduce stain accumulation.