Effect of Low-Concentration Chlorhexidine Mouthrinses on the Microleakage of Class V Resin Composite Restorations: An In Vitro Study

Objective: This in vitro study investigated the effect of two daily-use mouthrinses containing 0.05% chlorhexidine (CHX), with or without cetylpyridinium chloride (CPC), on the microleakage of standardized Class V resin composite restorations.Materials and Methods: Forty-five sound human premolars were included. Standardized non-beveled Class V cavities were prepared on the buccal surfaces and restored using a universal adhesive system and resin composite. After finishing, polishing, and thermocycling (1000 cycles, 5–55 °C), specimens were randomly assigned to three groups (n = 15): artificial saliva (control), CHX-only mouthrinse, and CHX + CPC mouthrinse. To simulate cumulative exposure equivalent to one year of daily use, each specimen was immersed in the assigned solution for 12 h. After methylene blue dye immersion and buccolingual sectioning, microleakage was assessed by stereomicroscopic examination at 40× magnification using an ordinal scoring system. A p-value of < 0.05 was considered statistically significant.Results: Mean microleakage scores were 1.80 ± 0.46 in the control group, 2.80 ± 0.65 in the CHX group, and 2.77 ± 0.62 in the CHX + CPC group. A statistically significant difference was observed among the groups (p < 0.001). Both CHX-containing mouthrinse groups showed significantly higher microleakage than the control group (p < 0.001), whereas no significant difference was found between the CHX and CHX + CPC groups (p = 0.870).Conclusion: Within the limitations of this study, prolonged exposure to low-concentration CHX-containing mouthrinses may compromise the marginal integrity of Class V resin composite restorations.