Effect of Maleic Anhydride Pretreatment on Tensile Bond Strength of a Silicone Soft Liner to a Denture Base Polymer

Purpose: To determine the effect of resin surface treatment with dissolved maleic anhydride in butanone added into primer on the tensile bond strength between an acrylic denture base resin and a silicone soft liner. Materials and Methods: To test tensile bond strength, standard dumbbell-shaped acrylic specimens were prepared. Five experimental groups, including the control, were tested (n = 5). Maleic anhydride solutions prepared in butanone at concentrations of 1%, 5%, 10% or 20% were then mixed with 1 ml of Primo adhesive and the mixtures were applied onto the resin bonding surfaces. Silicone liner material was applied to resin surfaces in the conventional manner. Tensile bond strength of the specimens was measured in a universal testing machine. Fractured surfaces were observed under the scanning electron microscope, and resulting chemical changes with the solutions used were analyzed spectroscopically. Results: The highest bond strength value was obtained for the group treated with 5% maleic anhydride (2.53 ± 0.48 MPa); the lowest value was for the group treated with 20% maleic anhydride (1.59 ± 0.29 MPa). Mixed failure was the dominant type seen in the experimental groups. Spectroscopic analysis showed the interaction of the anhydride carbonyl groups with the Primo primer. Conclusion: The treatment of resin surfaces with maleic anhydride added to Primo adhesive effectively increased bond strength between silicone soft liner and denture base resin. Keywords: PMMA, silicone soft liner, tensile bonding, SEM, FTIR, maleic anhydride