Comparative Evaluation of the Flexural Strength of Heat Polymerized Acrylic Resin with the Addition of 8% and 13% Aluminum Oxide Powder: An In-vitro Study

Introduction: Acrylic resins have been used successfully as denture bases. However, acrylic resin denture base materials are brittle and have poor strength and thermal conductivity. Therefore, it is essential to improve the flexural strength of heat polymerized acrylic resin. The present study aimed to evaluate and compare the flexural strength of heated polymerized acrylic resin with the addition of 8% and 13% aluminum oxide powder. Methods: In total, 90 acrylic specimens were fabricated and divided into three groups of A1 (unmodified heat-cured denture base resin), A2 and A3 (heat-cured denture base resin polymer modified with 8% and 13% by weight of aluminum oxide powder, respectively). The specimens were stored in distilled water for one week, and flexural strength was assessed using a universal testing machine. Data analysis was performed using one-way analysis of variance (ANOVA).  Results: Comparison of groups A1 and A2 (8%) showed the highest flexural strength (85.94 MPa) in group A2. A significant increase was observed in the values of flexural strength with 13% alumina addition. Comparison of groups A1 and A3 (13%) showed the highest flexural strength (86.41 MPa) in group A3, and the difference in the mean values of flexural strength was considered significant. Moreover, comparison of groups A2 and A3 indicated the highest flexural strength in group A3. Conclusion: Addition of alumina to conventional heat-cured acrylic resin shows increase in flexural strength. Increasing the flexural strength of acrylic resin base materials could results in higher clinical success rate.