Effect of denture cleaners on tensile bond strength between thermocycle aged acrylic resin base and silicone based soft lining material

In partial and complete dentures, soft lining materials are used in order to distribute the forces on the prosthesis equal and to reduce the occlusal load distribution in atrophic areas. Due to the differences in their chemical structures, bonding failure is a common problem, especially between silicone-based soft lining materials and PMMA. Different studies are being carried out to strengthen the connection between the soft lining and the acrylic base. Effective brushing for cleaning soft linings damages the surface and distrup its structure. For this, the use of denture cleaners is an effective method in preventing Candida colonization and denture stomatitis. There are many different methods and cleaner for the cleaning of dentures. However, denture cleaners used in clinical practice can also damage soft lining materials. The aim of our study is to investigate the effects of denture cleaners and airborne particle abrasion on the tensile bond strength between silicone-based soft lining material and acrylic resin base. In our research, 120 specimens were fabricated in dimensions of 10x10x40 mm using heat cured poly-methyl methacrylate denture base resin (Meliodent Heat Cure). All specimens were subjected to 10,000 thermal cycles of 5 to 55°C simulating 1 year of clinical use. The samples were randomly divided into 2 groups and one of the groups was sandblasted with 125 μm Al2O3 particles under 2 bar pressure from a distance of 10 mm for 10 seconds. Silicone-based soft lining material of 3 mm thickness was applied between two acrylic resins (Ufi Gel P). Sandblasted and non-blasted groups were randomly divided into 3 subgroups according to the cleaning material (%1 sodium hypochlorite, Corega and distilled water [control group]) used (n = 10). The samples were stored in 1% NaOCl solution for 10 minutes and in Corega solution for 3 minutes. 180 day denture cleaning was clinically simulated. All specimens were placed under tension until failure in a universal testing machine at a crosshead speed of 5 mm/minute. The tensile bond strengths were determined. The results were analyzed using two-way ANOVA and Tukey's post hoc test. The mean tensile bond strength was not significantly different among the studied groups. Sandblasting would not lead to significant increase in bond strength of soft liner to the denture base resin. The type of denture cleanser does not affect the tensile bond strength of silicone soft liners. Corega group has less effect on tensile bond strength compared to non-blasting distilled water and sodium hypochlorite groups. Keywords: Soft denture liner, airborne-particle abrasion, denture cleaners, tensile bond strength.