Effect of Different Surface Treatments on the Tensile Bond Strength Between a Heat-Polymerized Silicone-Based Soft Denture Liner and Heat-Cured Denture Base Resin: An In Vitro Study.

INTRODUCTION: The long-term clinical success of soft denture liners depends on the quality of adhesion between the resilient liner and the denture base resin. Inadequate bonding may result in debonding, microleakage, microbial colonization, and deterioration of the prosthesis performance. The purpose of our study was to assess the effects of various surface treatment techniques on the tensile bond strength of heat-polymerized silicone-based soft denture liners to heat-cured denture base resins. MATERIALS AND METHODS: This in vitro experimental study included 48 rectangular heat-cured polymethyl methacrylate specimens divided into six groups (n = 8) according to the surface treatment protocol: control, methyl methacrylate (MMA) monomer, phosphoric acid, sandblasting, laser + phosphoric acid, and laser + sandblasting. Following surface treatment, a heat-polymerizing silicone-based soft denture liner was bonded between the acrylic resin blocks. The tensile bond strength was evaluated using a universal testing machine, and the obtained values are expressed in megapascals (MPa). Statistical analysis was performed using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test, with p < 0.05 considered statistically significant. RESULTS: The sandblasting group presented the highest mean tensile bond strength (3.80 ± 0.41 MPa), followed by the MMA monomer group (3.45 ± 0.35 MPa) and the laser + sandblasting group (3.33 ± 0.80 MPa). The control group showed the lowest tensile bond strength (2.86 ± 0.44 MPa). A one-way ANOVA showed a statistically significant difference between the study groups (F = 2.746, p = 0.031). Tukey's post hoc analysis revealed a significant increase in tensile bond strength in the MMA monomer group compared to the control group (p = 0.015). The sandblasting group showed significantly higher bond strength than the control group (p < 0.001), phosphoric acid group (p = 0.012), and laser + phosphoric acid group (p = 0.004). CONCLUSION: Surface treatment methods had a significant influence on the tensile bond strength between the heat-polymerizing silicone-based soft denture liner and the heat-cured polymethyl methacrylate denture base resin. Among the evaluated techniques, sandblasting demonstrated the highest tensile bond strength and was found to be the most effective surface treatment method under the conditions of this study.