OBJECTIVE: To evaluate the influence of in situ acid erosion on the structural and optical properties of nanoparticulate bisacrylic resin with different surface treatments, evaluating surface roughness (Ra), knoop microhardness (KHN), color change (ΔE, ΔL, ΔC, ΔH), contrast (CR) and translucency (TP). METHODS: Eighty specimens were made (n = 10 per group) and the following surface treatments were applied: U RESULTS: The S CONCLUSION: The surface sealants were able to improve the surface roughness and microhardness of the bisacrylic resin, however, the Palaseal sealant generates unacceptable color change. The acid injection did not significantly influence the properties of the material, regardless of the surface treatment performed.