Adhesion of acrylic resins to different silicone elastomers – laboratory investigations

The establishment of a permanent, strong, gap-free connection between a soft lining and the denture base material (acrylic resin) represents a significant laboratory and clinical requirement. Objectives: Present study aimed at assessment of the resistance of the Superacryl acrylic resin bonds with different silicone elastomers: Molloplast B (heat-temperature vulcanized - HTV material), Mucopren, Mollosil, Ufi Gel C, Permaquick (room-temperature vulcanized - RTV materials). Method: The total of 75 acrylic samples in the form of rods of 8 mm diameter were connected to each other by 3 mm thick layer of elastic material. There were 15 such samples and all of them were tested in the Instron 1193 (Instron Ltd, UK) testing machine. The tensile test was used. The data were assessed statistically using the ANOVA method. Results: The mean values and standard deviations of disrupting stress of acrylic resin and Molloplast B amounted 1.39 ±0.24 N/mm² and corresponded to the mean extension in moment of disrupting coming to 5.7 ±1.8 mm. For silicone RTV elastomers those values amounted adequately for Mucopren: 1.28 ±0.25 N/mm² by 4.3 ±1.6 mm, for Mollosil: 1.24 ±0.28 N/mm² by 4.7 ±1.9 mm, for Ufi Gel C: 1.13 ±0.18 N/mm² by mean extension 7.1 ±1.9 mm and for Permaquick: 0.78 ±0.17 N/mm² by 7.0 ±1.8 mm. The best resistance was obtained for the bond of the Molloplast B. All its samples broke cohesively. There were not significant differences between the bonds of Mucopren, Mollosil, Ufi Gel C and Molloplast B in its mechanical properties. The disrupting stress of the Permaquick bonds was lower and differed significantly from four preceding bonds. Conclusion: The disrupting stress of HTV elastomer bonds was higher than RTV silicone materials bonds, but the extension in moment of disrupting was higher for RTV materials bonds.