Physical and mechanical properties analyses of zirconia reinforced experimental nanohybrid dental composite (NHDC) from rice husk
Noor Huda Ismail, Lo Szi You, Aimi Najwa Abd Jalil, Noor Baizura Ab Ghani, Raja Azman Awang
Reinforcement of zirconia into dental composite is developed to improve strength. This study aimed to analyze the effects of zirconia on Vickers hardness (VHN), microstructure, compressive strength (CS), and degree of conversion (DC) of experimental nanohybrid dental composite (NHDC). Specimens were prepared according to zirconia reinforcement and mixing methods: Negative control (without zirconia), Mixing method I (3 wt % zirconia), Mixing method I (5 wt % zirconia), Mixing method II (3 wt % zirconia), Mixing method II (5 wt % zirconia), and Positive control (Filtek Z250; 3M ESPE). VHN, CS and DC were analyzed using hardness tester, universal testing machine, and Fourier transform infrared (FTIR) spectroscopy, respectively. VHN were significantly increased (3 wt % and 5 wt %) (p < 0.001). DC was reduced; however, DC values were all above the acceptable 60 %. An increased compressive strength with the zirconia (3 wt % and 5 wt %) compared to negative control, however the differences were not statistically significant (p > 0.05). Representative scanning electron microscopy micrographs revealed a pattern of homogenous distribution of the filler in all samples. There was no significant difference in physical and mechanical properties between NHDCs fabricated using different mixing methods. Zirconia reinforcements may increase the CS and VHN of NHDC, without compromising the DC.