Effects of Methacrylic Acid on Physical/Mechanical Properties and Biocompatibility of Urethane-Based Denture Biomaterials

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We have demonstrated that urethane-based denture biomaterials with 10% methacrylic acid (MAA) could bind and then slowly release antifungal drug for months. Drugs on the resins could be repeatedly quenched/recharged, and in subsequent recharging, they could be changed/switched to more potent/effective ones. However, the physical/mechanical properties and biocompatibility of the new MAA-based resins are currently unknown. The objective of the current study is to evaluate the effects of copolymerization with MAA on physical/mechanical properties and biocompatibility of urethane-based denture resin materials. MAA and diurethane dimethacrylate (UDMA) were copolymerized using initiator azobisisobutyronitrile (AIBN). Water sorption and solubility were assessed with the specifications of ISO (International Standards Organization) test method 1567, flexural strength and modulus were measured according to ASTM D-790, and biocompatibility was preliminarily evaluated in cytotoxicity assay using mouse 3T3 fibroblast cells with the trypan blue method. The results demonstrated that copolymerization of UDMA with up to 10% MAA did not negatively affect water sorption/solubility, flexural strength/modulus, and biocompatibility. With 20% MAA, however, the mechanical properties of the resulting resins were significantly decreased. To sum up, UDMA-MAA copolymers with up to 10% MAA had adequate physical/mechanical properties for denture materials with no side effects on cell viability. The UDMA-MAA denture biomaterials have a good potential to be used clinically for managing CADS and other related infectious conditions.