Effect of Curing Time on the Mechanical Properties of a High Viscous PMMA Cement Available to Purchase

It has been found from our previous studies that the time of curing of high viscous polymethylmethacrylate (HV-PMMA) cement influences the shear strength of titanium (Ti) implant/ HV-PMMA cement samples during pull out static tests, although the reason for the influence is not understood yet. This study hypothesizes that time of curing of cement influences the strength and hardness of the cement adjacent to the implant, which resulted in the variability of the shear strength between Ti and cement. To test this hypothesis, this study conducted ASTM standard three point bend (3PB) test on a HV-PMMA cement to measure the flexural strength of HV-PMMA cement that was cured for 10 and 60 minutes. In addition, this study conducted pull out tension tests on Ti/ HV-PMMA cement to measure the shear strength between Ti and HV-PMMA cement that was cured for 10 and 60 minutes. The hardness of the HV-PMMA cement at the adjacent to Ti was measured using a Rockwell R hardness test scale. Two groups of samples were produced for each type of experiments by varying the curing times: 10 and 60 minutes. The cement during the liquid phase poured into a custom made mold to create the 3PB cylindrical samples. For the pull out tension tests on Ti/cement samples, the Ti implant was fastened at the top gripper and a custom made holder that has a hole was fastened at the bottom gripper of universal mechanical test system. Cement was poured in to the gap between implant and holder. The cement was cured for an hour. This study found that the curing time significantly increases the values of bending, shear and hardness properties (p<0.05). The study concludes that the variability of the shear strength between Ti and cement depends on the strength and hardness of the cement adjacent to the implant.