Effect Of Incorporation of Zirconium Oxide Nanoparticles on Thermal Conductivity and Microhardness of PMMA Heat Polymerized Acrylic Denture Base Material - An Invitro Study

Soumya Jagithyala, Dr. Angadi Kalyan Chakravarthy, Dr. Shobarani B., Dr. Ramavarapu Avinash, Dr. Alaveni Manga Narsingoju, M. Hari Chandana

Abstract: Introduction: Poly (methyl methacrylate) (PMMA) is widely used in denture base fabrication due to its favourable properties. However, limitations such as low thermal conductivity, poor mechanical strength, and susceptibility to microbial adhesion necessitate modifications to improve its performance. Zirconium oxide (ZrO?) nanoparticles have shown promise in enhancing the mechanical and thermal properties of PMMA - based denture materials. Objective: This study aimed to evaluate the effect of incorporating different concentrations of zirconium oxide nanoparticles (3%, 7%, and 10%) on the thermal conductivity and microhardness of heat - cured PMMA denture base resin. Materials And Methods: Total 80 Heat - cured PMMA samples were fabricated using stainless steel molds, following standard processing techniques. The samples were reinforced with ZrO? nanoparticles at varying concentrations and divided into four experimental groups. Thermal conductivity was measured using the Cussons Thermal Conductivity Apparatus, while microhardness was assessed using a Vickers Hardness Tester. Data were analyzed using one - way ANOVA and Tukey?s post hoc test, with statistical significance set at p < 0.05. Results: The incorporation of zirconium oxide nanoparticles significantly improved the thermal conductivity and microhardness of PMMA resin. The 10% ZrO? group exhibited the highest microhardness and thermal conductivity values compared to the lower concentrations. However, a trade - off was observed, where increasing ZrO? concentration beyond 7% the rate of improvement may slow as the material percentage approaches 10% this is due to higher concentrations nanoparticles tend to agglomerate leading to uneven distribution with in the resin matrix This hinders the formation of continuous thermal pathways and reduced processability of the resin. Conclusion: Zirconium oxide nanoparticle reinforcement enhances the thermal and mechanical properties of PMMA denture base materials. The 7% ZrO? concentration demonstrated the optimal balance between improved properties and material workability, making it a suitable form for clinical applications. Further studies should evaluate long - term durability and biocompatibility in oral conditions.

Keywords: PMMA, zirconium oxide nanoparticles, denture base resin, thermal conductivity, microhardness