Comparison of Flexural Strength and Flexural Modulus of Conventional and Graphene-Reinforced Polymethyl-Methacrylate under Thermocycled and Non-Thermocycled Conditions: An in-Vitro Study

Abstract

Background and Objective: Polymethyl methacrylate (PMMA) is widely used as a denture base material, but its major disadvantage is its low flexural strength. Graphene has recently been proposed as a reinforcing nanofiller due to its superior mechanical properties, but evidence regarding its incorporation into PMMA and the influence of thermocycling remains limited. This study aimed to evaluate the effect of graphene reinforcement on the flexural strength (FS) and flexural modulus (FM) of PMMA and to assess the impact of thermocycling on these properties. Methodology: Seventy-six PMMA samples were fabricated and divided into two groups: conventional PMMA (n = 38) and G-PMMA reinforced with 0.25 wt% graphene (n = 38). Each group was further subdivided into thermocycled and non-thermocycled groups (n=19). All samples were subjected to three-point bending tests using a universal testing machine (UTM). Data was analyzed using a two-way ANOVA followed by Bonferroni correction. (p < 0.05). Results: G-PMMA displayed higher mean FS and FM than conventional PMMA in both thermocycled and non-thermocycled groups. Anova showed a statistically significant difference in flexural strength after thermocycling between PMMA and G-PMMA (p = 0.04), and for flexural modulus, PMMA vs G-PMMA, thermocycling, and their interaction had significant effects (p = 0.043, p = 0.016, and p < 0.001, respectively). Followed by pairwise comparisons, which revealed a statistically significant difference on FS between PMMA and G-PMMA after thermocycling. (p = 0.03) Conclusion: G-PMMA demonstrated significantly improved flexural strength and modulus compared to conventional PMMA. Thermocycling had no significant effect on flexural strength but influenced flexural modulus, indicating its impact on material stiffness rather than strength.