Effect of Injection Molding and Sintering Behaviors on Y-TZP Dental Implants

Abstract

This study seeks to optimize injection molding and sintering process parameters obtained using the Taguchi method. Mold flow analysis software was applied to simulate the injection molding process to improve mold design. Shrinkage rates of critical dimensions from both injection molding and sintering process analysis could be used to improve mold design. Density, Vickers hardness, and shrinkage rates of zirconia dental implants were carried out on the sintered dental implants, respectively, using Archimedes principle, Vickers hardness tester, and optical projectors. The simulation results show that the injection molding process with optimal parameters significantly reduced shrinkage rates as compared to results using the initial parameters. On the other hand, the measurement results show that zirconia dental implants sintered with optimal design parameters could achieve a density of 5.96 g/cm3, a hardness of Hv 1489 ± 131, and a shrinkage rate of 20.82 ± 0.70%. Analysis of variance (ANOVA) results revealed that the most influential factor was the sintering temperature, which was thus used as the key variable in the subsequent single factorial experiments. With sintering temperatures controlled between 1400°C to 1500°C, density increased from 5.96 g/cm3 to 6.00 g/cm3, hardness from 1489 ± 131 to 1489 ± 71, and the shrinkage rate from 20.82 ± 0.70% to 21.34 ± 0.20%.