Color stability of bulk-fill and conventional composite resins following exposure to different mouthrinses: an in vitro study

Objective: The efficacy of composite restorations depends on their color stability, with discoloration cited as a principal reason for restoration replacement. The current investigation focused on assessing the influence of various mouthrinses on the color stability of conventional and bulk-fill composites. Methods: In this in vitro study, 40 samples (4 mm in diameter and 4 mm in thickness) were constructed from Tetric N-Ceram and Tetric N-Ceram Bulk Fill composites (both from Ivoclar Vivadent). The initial color value of each specimen was recorded using an Easyshade spectrophotometer, in adherence with the CIELab color scale. Subsequently, the specimens were submerged in 20 mL of either distilled water or different mouthrinses including non-alcohol Misswake, alcohol-containing Listerine, or chlorhexidine. After incubating for 24 hours at 37°C, color values were measured again. The data were analyzed by two-way ANOVA, and a P-value 0.05 was considered statistically significant. Results: Tetric N-Ceram demonstrated superior color stability compared to the Tetric N-Ceram Bulk Fill composite after immersion in non-alcoholic Misswake and alcohol-containing Listerine mouthwashes (P 0.05). In both composites, chlorhexidine exhibited the most pronounced color change (P 0.05). The color change was significantly greater in the alcohol-containing Listerine than in the non-alcoholic Misswake mouthrinse (P 0.05). Conclusions: This study suggests that mouthrinses, especially chlorhexidine, significantly affect the color stability of both composite types, with conventional composites showing relatively more resistance to color change than bulk-fill composites.