Abstract
Purpose To evaluate and compare the surface properties (roughness and hardness) of poly(methylmethacrylate) denture base material modified with zirconium dioxide (ZNPs), silicon dioxide (SNPs), and diamond (DNPs) nanoparticles.
Materials and methods Two hundred sixty heat-polymerized acrylic resin disks (15 x 2 mm) were prepared. ZNPs, SNPs, and DNPs were added in concentrations of 0%, 0.5%, 1.0%, 2.5%, and 5.0% by weight of acrylic powder. This yielded a total of 13 groups for each test according to filler type and concentration (n = 10/group). The control group was made of pure acrylic. A mechanical polisher was used to standardize specimens' surfaces before testing. A profilometer and Vickers hardness indenter were used to test the surface roughness and hardness, respectively. ANOVA and Tukey post hoc tests were used for data analysis (alpha = 0.05).
Results In comparison to control, results showed a nonsignificant increase in surface roughness (R-a) of acrylic material after the addition of 0.5% nanoparticles (ZNPs p = 0.168, SNPs p = 0.166, and DNPs p = 0.177), while a significant increase was seen with all other concentrations (p < 0.05). R-a values of ZNP and DNP groups were significantly higher than those of the SNPs group (p < 0.001). The addition of any of the fillers to acrylic denture base materials significantly increased the hardness (p < 0.05), with ZNPs and DNPs having values lower than those of the SNPs group (p < 0.001).
Conclusions Although nanofiller addition increased the hardness of denture base material, R-a was adversely affected when the concentration exceeded 0.5%. Therefore, 0.5% is suggested to be the most appropriate ratio to improve hardness with acceptable R-a.