Background: Various fluids in the oral environment can affect the surface roughness of resin composites. This in vitro study was conducted to determine the influence of the mouth rinses on surface roughness of two methacrylate-based resin (nanofilled and packable composite) and siloraine-based resin composites.

Materials and methods: Disc-shaped specimens (12 mm in diameter and 2mm in height) were prepared from three types of composite resin materials: Filtek™ Z350 XT, Filtek™ P60 and Filtek™ P90.Thirty specimens were prepared from each composite type and subdivided into three subgroups (n=10) according to the type of treatment solution: distilled water (control), Listerine (alcohol-containing), Sensodyne Pronamel (alcohol free fluoride- containing).Each subgroup was immersed in 20 ml of treatment solutions and incubated at 37°C for 24 hr and then subjected to surface roughness test by profilometer .The resulting data were statistically analyzed using ANOVA and LSD test at0.05 significance level.

Results: The results of this study showed that both mouth rinses irrespective of the presence or absence of alcohol resulted in significant increase in the surface roughness of the tested resin composite materials compared to control with no significant difference between the two mouth rinses. Comparison among the three types of resin in each treatment solution showed that there was a statistically high significant difference in surface roughness between all subgroups 

Conclusion: Both alcohol-containing and alcohol-free fluoride containing mouth rinses cause highly significant increase in surface roughness of composite resins. Composite changes depended on the material itself rather than the mouth rinse solution used.

Key words: Composite resin, mouth rinses, siloraine, surfaces roughness.