The Effect of UDMA/TEGDMA Mixtures and Bioglass Incorporation on the Mechanical and Physical Properties of Resin and Resin-Based Composite Materials

Incorporating Bioglass into dental composites may improve biocompatibility and aid tooth and bone tissue remineralisation. This study aimed to determine the impact of Bioglass and silica filler on the mechanical and physical properties of cured photopolymers. Hardness (Vickers microhardness test), flexural strength (FS), and flexural modulus (FM) (three-point bend test) of resins containing various urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) and bisphenol A-glycidyl methacrylate (bisGMA)/TEGDMA concentrations (20–80 mass%) were tested. Degree of conversion (DC), FS, and FM of resin composites containing nonsilanised irregular 45S5-Bioglass (50？μm; 5–40 mass%) and/or silanised silicate glass filler particulates (0.7？μm; 30–70 mass%) were tested. Data was analysed using one-way ANOVA. UDMA/TEGDMA resins exhibited increased hardness and FM compared with bisGMA/TEGDMA resins. Addition of Bioglass particles to 60/40？wt% UDMA/TEGDMA or bisGMA/TEGDMA resins may enable the development of new materials that exhibit higher or at least equivalent values of DC, FS, and FM compared with conventional resin composites. 1. Introduction Conventional light-cured dimethacrylate resin composites undergo free radical photopolymerisation in response to blue light (wavelength 450–500？nm). The resin composites contain monomers such as bisGMA, UDMA, and TEGDMA (used as a diluent) in the organic matrix, a ketone-amine initiator/coinitiator system and inert silicate filler particles [1, 2]. UDMA is increasingly used in the organic matrix of resin composites for dental applications [1], due to the flexibility and strength conferred by the urethane group [2, 3]. These properties may result in enhanced physical and mechanical properties of resin-based UDMA composites compared with resins containing bulky bisGMA molecules [4]. Although conventional resin composites have been a successful restorative dental material, there is no beneficial biological interaction between the surrounding tissues and the material. By incorporating an optically suited, bioactive glass into these resins, the biocompatibility with the surrounding tissues and remineralisation processes may be improved [3]. The aim of this project was to determine the effect of mixing various comonomer base resin ratios and the impact of the incorporation of silica filler and Bioglass on the mechanical and physical properties of the cured photopolymer composite. 2. Methods 2.1. Resin Synthesis All materials were supplied by Sigma-Aldrich, UK, and used as received. A variety of UDMA/TEGDMA and