Comparative Evaluation of the Impact Strength of Polymethyl Methacrylate Heat-cure Acrylic Denture Base Resin Reinforced with Aramid Fibres and Glass Fibres: An In-vitro Study

Introduction: Polymethyl Methacrylate (PMMA) is widely used as the material of choice for denture base fabrication due to its favourable handling properties, aesthetics, and costeffectiveness. However, its low fracture and impact resistance remains a major clinical limitation, often leading to denture failure. Reinforcement of PMMA with fibres such as aramid and glass has been proposed to enhance its mechanical properties. Aim: To compare the impact strength of conventional heat-cure PMMA denture base resin, PMMA-reinforced with aramid fibres, and PMMA-reinforced with glass fibres. Materials and Methods: This in-vitro experimental study was conducted at the Department of Prosthodontics, Maratha Mandal’s Nathajirao G. Halgekar Institute of Dental Sciences and Research Centre, Belagavi, Karnataka, India from a period of 6 month from June 2025 to December 2025. A total of 30 rectangular test specimens were prepared using preformed stainless-steel metal dies (50×10×3 mm) with a 45-degree notch at the center. The specimens were divided into three groups (n=10 each): Group A: Conventional heat-cure PMMA (control), n=10, Group B: PMMA-reinforced with aramid fibres (1% by weight) n=10, Group C: PMMA-reinforced with glass fibres, n=10. A monomer-polymer ratio of 1:2 by weight was used. After reaching the dough stage, the material was packed, processed at 73°C for 30 minutes, bench-cooled, and deflasked. The specimens were tested using an Izod impact strength testing machine with a load of 2.9 joules/m. Impact strength was recorded in joules and kJ/ m². Statistical analysis was performed using One-way Analysis of Variance (ANOVA) for overall comparison and the Bonferroni Posthoc test for intergroup comparison with p≤0.05 was considered statistically significant. Results: The highest impact strength was observed in Group B (aramid fiber reinforced PMMA), followed by Group C (glass fiber reinforced PMMA), and lowest in Group A (control). Statistically significant differences were observed between Group B and Group C (p<0.001) and between Group C and Group A (p =0.021). However, the difference between Group B and Group A was statistically insignificant (p = 0.199). Conclusion: Within the limitations of this in-vitro study, incorporation of 1% by weight aramid fibres into heat-cure PMMA significantly improved the impact strength compared to conventional PMMA. Fiber reinforcement, particularly with aramid fibres, can be considered a promising approach to enhance the fracture resistance of denture base resins.