Investigation of the Thermal Conductivity and Flexural Strength of Polymethylmethacrylate Denture Base Material with SiC and Al2O3 Added

Although polymethylmethacrylate (PMMA) is widely used as a denture base material, its disadvantages include low strength and low thermal conductivity. The effects on thermal conductivity, flexural strength, thermal diffusivity, and elastic modulus of adding Al2O3 and SiC powders in different volumes to PMMA were investigated. A total of 60 specimens were prepared in 10 groups (five groups for the thermal conductivity test and five groups for the flexural strength test (n:6). The specimens were immersed in water for 30 days before the testing. Thermal conductivity values were measured by the transient hot bridge (THB) method, and flexural strengths were measured by the 3-point bend test. A significant difference was found in thermal conductivity, flexural strength, thermal diffusivity and elastic modulus values between independent groups (P <0.001) using the Kruskal-Wallis test. The Kruskal Wallis 1-way ANOVA was used for the post hoc tests after Kruskal Wallis (alpha=.05). The thermal conductivity of PMMA increased significantly with the addition of 15% SiC and 15% Al2O3. The flexural strength values decreased significantly with the addition of 10% SiC and 15% Al2O3. The thermal diffusivity values increased significantly with the addition of 10% and 15% SiC. The Young modulus of PMMA decreased when 10% SiC, 10% Al2O3 and 15% Al2O3 were added. Environmental scanning electron microscope (ESEM) showed that ceramic powders were dissipated in PMMA. The addition of 15% SiC powders to PMMA increased thermal conductivity without significantly reducing flexural strength. This study helped determine the optimum volumes for the use of SiC and Al2O3 powders. Knowledge of the importance of this variable will help in more effective modification of denture base resin with SiC and Al2O3 powders to improve heat transfer without adversely affecting strength.