The nature of the interface between polymethyl methacrylate denture base materials and soft lining materials

Abstract

Four of the commonly used resilient denture lining materials were investigated. They were of different chemical composition, physical forms and processing cycles. Scanning electron microscope examinations of the interface between the liners and the regular acrylic resin base material were carried out in an attempt to assess the bonding of these materials to the denture base, and to evaluate the reliability of their use. The physical and mechanical bonding properties of the resilient lining materials to acrylics were studied, which included tensile, shear, peel and compression tests to measure the efficacy of the joint between the acrylic and the lining materials and its resistance to various external damaging loads. The effect of water on the liner/denture base interface and on the liner's bonding properties to acrylics was also investigated, and the validity of roughening the tissue surface of the denture base prior to processing the liner was assessed. The findings point to the advisability of using the acrylic type of soft liners whenever resilient liners are indicated. Roughening the fitting surface of the denture base to which the resilient lining materials are to be applied has a weakening effect on the bond between the lining and the denture base. Long-term exposure of the liners to water has a destructive effect. The infusion of the water into the material leads to swelling and stresses build up at the denture base interface and these tend to promote distortion and reduction in bonding.