Comparison of Thermal Conductivity, Flexural Strength, and Surface Hardness of Alumina Incorporated and Conventional Heat-Activated Denture Base Resins

ABSTRACT

Introduction: Commonly used polymethyl methacrylate (PMMA) denture base material cannot be considered as ideal due toinferior thermal and mechanical properties.Aim: The aim of the study was to evaluate and compare the thermal conductivity, flexural strength, and surface hardness ofheat cure acrylic resin incorporated with 10 wt.% and 15 wt.% alumina and conventional denture base resin.Materials and Methods: A total of 108 specimens were prepared. Specimens were divided into three main groups. Group Aspecimens were disk shaped (50 mm × 5 mm) and used for measuring thermal conductivity. Groups B and C specimens wererectangular shaped (65 mm × 10 mm × 3 mm) and were used for measuring flexural strength and surface hardness, respectively.Each group was further divided into three subgroups (1, 2, and 3) depending on the concentration, namely, PMMA without filler(control), PMMA + 10 wt.% of Al2O3, and PMMA + 15 wt.% of Al2O3 containing 12 samples each. Thermal conductivity wasmeasured using a modified guarded hot plate apparatus. Flexural strength was assessed with a three-point bending test usinga universal testing machine. Hardness testing was conducted using a Vickers Hardness Tester. The results were analyzedusing one-way ANOVA followed by post hoc comparison by Tukey’s method.Results: Mean values of thermal conductivity were (in W/mK) 0.190, 0.231, and 0.275 for subgroups A1, A2, and A3, respectively.The mean flexural strength values were (in MPa) 56.62, 66.73, and 74.24 for subgroups B1, B2, and B3, respectively. Meanvalues of surface hardness was calculated to be (in HV) 15.17, 16.51, and 17.91 for subgroup C1, C2, and C3, respectively.There was statistically significant improvement in thermal conductivity, flexural strength, and surface hardness after incorporationof alumina and the increase was in proportion to the weight percentage of alumina filler.Conclusion: Incorporation of alumina into heat cure denture base resin significantly improved the thermal conductivity, flexuralstrength, and surface hardness.