B Background: Nanofiller composite resin is a widely chosen dental restorativematerial due to its its excellent aesthetics and mechanical strength, however itexhibits the physical property of fluid absorption. The consumption of acidic foodsand beverages can influence the surface roughness of nanofiller composite resin.The low pH of dairy-based and plant-based yoghurt may cause degradation ofnanofiller composite resin. Objective: To determine the difference in the effects ofimmersion in dairy-based and plant-based yogurt on the surface roughness ofnanofiller composite resin. Methods: This study employed an experimentallaboratory design with a post-test with control group design. A total of 30 samplesof nanofiller composite resin, each 6 mm in diameter and 2 mm in height, wereprepared using stainless steel molds. The control group was immersed in artificialsaliva for 24 hours, while the treatment groups were immersed for 2 hours in dairybased yogurt and plant-based yogurt, followed by immersion in artificial saliva for22 hours. The immersion process was carried out for 10 days in an incubator at37°C. Surface roughness was tested using a surface roughness tester. Results: Theresults of the One-Way ANOVA test for surface roughness (p = 0.000) indicated asignificant difference. The Post Hoc Tukey test showed significant differencesbetween the control group and dairy-based yogurt, the control group and plantbased yogurt, and between dairy-based and plant-based yogurt. Conclusion: Therewere differences in surface roughness values, with the highest roughness observedin the dairy-based yogurt group due to its more acidic pH compared to plant-basedyogurt.