A Comparative Evaluation of Thermal Conductivity and Compressive Strength of Heat Cure Resin Modified with Nanoparticles – A Vitro Study

Abstract

Introduction: Polymethyl methacrylate (PMMA) is widely used as a denture base material; however, its low thermal conductivity and limited mechanical strength may compromise patient comfort and prosthesis durability. Incorporation of nanoparticles has been suggested to enhance these properties.

Objectives: To evaluate and compare the thermal conductivity and compressive strength of heat-cured PMMA reinforced with 1 wt% titanium dioxide (TiO₂), silver nanoparticles (AgNPs), and zirconium dioxide (ZrO₂). Methods: Forty disc-shaped heat-cured PMMA specimens (35 mm × 5 mm) were fabricated and divided into four groups (n = 10): unmodified

PMMA (control), PMMA + 1% TiO₂, PMMA + 1% AgNPs, and PMMA + 1% ZrO₂. Nanoparticles were homogeneously blended with the PMMA polymer prior to conventional processing. Specimens were stored in distilled water at 37 °C for 48 hours. Thermal conductivity was assessed using the guarded hot plate method, and compressive strength was measured using a universal testing machine. Statistical analysis was performed at a significance level of p < 0.05.

Results: All nanoparticle-modified groups showed statistically significant differences compared with unmodified PMMA (p < 0.05). AgNP-reinforced PMMA exhibited the highest thermal conductivity. ZrO₂-reinforced PMMA demonstrated the greatest compressive strength, followed by TiO₂. AgNP incorporation resulted in reduced compressive strength compared with the control.

Conclusion: Nanoparticle reinforcement significantly influenced the thermal and mechanical properties of heat-cured PMMA. AgNPs enhanced thermal conductivity, whereas ZrO₂ provided superior mechanical strength. Nanofiller selection should be tailored to specific clinical requirements.