Objective: Mouthwashes containing chlorhexidine can cause discoloration in restorative materials when used for the long-term. To prevent staining of a restorative material, several protective materials are used. The aim of this in vitro study was to evaluate the impact of a surface sealant on the color stability of a nano-hybrid composite resin material immersed in different mouthwashes.

Methods: A total of 42 composite resin discs (10x2 mm) were prepared with a nano-hybrid composite resin (Herculite XRV Ultra) using Teflon moulds. The composite specimens were first divided into two groups (with or without a surface sealant) then into three subgroups (n=7) according to the mouthwashes (Gengigel, Oderol, and Chlorhex). After SS application to 21 specimens, all the discs were subjected to baseline color measurements using a spectrophotometer according to the Commission Internationale de l’Eclairage Lab* system. The specimens underwent thermal cycling. Following immersion in different mouthwashes for 24 hours, the color measurements were repeated. The ∆E data were assessed using Kruskal-Wallis one-way ANOVA. Mann-Whitney U test was performed for different immersion mouthwashes (p<0.5).

Results: Statistically significant differences (p<0.5) were found between the unsealed composite specimens immersed in Chlorhex and the other mouthwashes in terms of ∆E values. The Chlorhex appeared to be associated with the most severe alteration in color (5.14±0.83), followed by Gengigel (2.21±1.46) and Oderol (1.94±1.75). There were no statistically significant differences (p>0.05) between the sealed and unsealed composite specimens in terms of the color changes.

Conclusion: The application of a low viscosity liquid surface sealant material did not show the expected effect on the color stability of a nano-hybrid composite resin in terms of three different mouthwashes.