Effectiveness of microwave sterilization on tensile strength of Polymethylmethacrylate denture base resin reinforced with glass Fibres: an in vitro study

Statement of problem: Glass fibres reinforcement and microwave polymerization, both has been suggested as a method to improve the mechanical strength of acrylic denture base. However the post polymerization effect of microwave sterilization on Polymethylmethacrylate Denture Base Resin Reinforced with Glass Fibre has not been investigated. Purpose. The study analyzed the effect of microwave Sterilization on Tensile Strength of Polymethylmethacrylate Denture Base Resin Reinforced with Glass Fibres. Materials and Methods: In this study Heat cure acrylic denture base resin material and loose glass fibres of diameter 12 microns and length 15 mm, were used. A total of 30 specimens were polymerized by conventional heat cure according to manufacturer's instruction and divided into 3 groups (N=10). Group A is control, Group B is acrylic resins reinforced with 5% glass fibres, and Group C is acrylic resins reinforced with 5% glass fibres, sterilized by microwave. Group C specimens were subjected to post polymerization sterilization in a microwave oven in power 800W and time setting of 5 minutes. Tensile strength load measurements were made using universal testing machine at a crosshead speed of 3 mm/min with a span of 10 mm. The tensile strength values were calculated in Newton/mm2. Data analysis included one-way ANOVA and independent t- test. *Results: The tensile strength of Group C with application of microwave irradiation for sterilization, demonstrated significant strength improvement with respect to Group B and Group A. There was a statistical significant difference seen in between the groups (p=0.001). Conclusion: Microwave post polymerization irradiation for sterilization of acrylic resin prosthesis reinforced with glass fibres can be an effective method for increasing the tensile strength of acrylic resin.