Hardness evaluation of PMMA reinforced with two different calcinations temperatures of ZrO₂-Al₂O₃-SiO₂ filler system

Polymethyl methacrylate (PMMA) is one of the materials used for the temporary crown while making fixed partial dentures. Unfortunately, it has low mechanical properties. This study aim's to improve PMMA hardness by adding ZrO₂-Al₂O₃-SiO₂ filler system in two different calcination temperatures. Thirty-two disc form samples with 8mm diameter x 3mm thickness were made from two category-filler based that had been previously evaluated using Scanning Electron Microscope (SEM). Each category was divided into six groups of three respectively from a controlled and different concentrations of 7(A), 9(B), 11(C), 13(D), and 15(E) weight % of reinforced filler system, then tested with Vickers Hardness Tester. Filler particles that calcined at 550° can increase to 700° consist of fine crystalline and amorphous phases; however, the sample shows the highest hardness about 20,19 VHN even though the increase is only 7,5% compared to control. Meanwhile, the sample that calcined at 700°C exhibiting the highest hardness about 15,66 VHN corresponds to sample D, it has increased 25% compared to the control. This is correlated with microstructure result that has more growth crystalline particles. The results were analyzed by ANOVA which determined were not statistically significantly different (p<0.05). Therefore, it can be concluded that the 13% reinforced ZrO₂-Al₂O₃-SiO₂ filler system calcined at 700°C shows the highest hardness increase compare to calcination temperature 550-700°C. Although it is not significantly different.