THE EFFECT OF POLY(METHYL METHACRYLATE) SURFACE TREATMENTS ON THE ADHESION OF SILICONE-BASED RESILIENT DENTURE LINERS

Statement of problem. Different surface treatment protocols of poly(methyl methacrylate) have been proposed to improve the adhesion of silicone-based resilient denture liners to poly(methyl methacrylate) surfaces. Purpose. The purpose of this study was to evaluate the effect of different poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners. Material and methods. Poly(methyl methacrylate) specimens were prepared and divided into 4 treatment groups: no treatment (control), methyl methacrylate for 180 seconds, acetone for 30 seconds, and ethyl acetate for 60 seconds. Poly(methyl methacrylate) disks (30.0x5.0 mm; n=10) were evaluated regarding surface roughness and surface free energy. To evaluate tensile bond strength, the resilient material was applied between 2 treated poly(methyl methacrylate) bars (60.0 x 5.0 x 5.0 mm; n=20 for each group) to form a 2-mm-thick layer. Data were analyzed by) 1-way ANOVA and the Tukey honestly significant difference tests (alpha=.05). A Pearson correlation test verified the influence of surface properties on tensile bond strength. Failure type was assessed, and the poly(methyl methacrylate) surface treatment modifications were visualized with scanning electron microscopy. Results. The surface roughness was increased (P<.05) by methyl methacrylate treatment. For the acetone and ethyl acetate groups, the surface free energy decreased (P<.05). The tensile bond strength was higher for the methyl methacrylate and ethyl acetate groups (P<.05). No correlation was found regarding surface properties and tensile bond strength. Specimens treated with acetone and methyl methacrylate presented a cleaner surface, whereas the ethyl acetate treatment produced a porous topography. Conclusion. The methyl methacrylate and ethyl acetate surface treatment protocols improved the adhesion of a silicone-based resilient denture liner to poly(methyl methacrylate).