RESUMO
Ambient temperature and time to implantation can affect the material properties of polymethylmethacrylate bone cement, and cement intrusion depth has been shown to affect implant fixation. The purpose of this study was to examine the effects of ambient temperature and time to implantation on depth of intrusion, and the effect of ambient temperature on setting time. Two types of cements were evaluated: cement A (Simplex P,medium Q7 viscosity) and cement B (Palacos R, high viscosity). Dough, working and setting times were determined, as well as intrusion depth, at different temperatures per American Society of Testing and Materials (ASTM) protocol F451. A vacuum mixer was used in a temperature- and humidity-controlled environment at 60, 65, and 70°F. At each temperature, the cement was placed into an intrusion mold at 0, 50, and 100% of working time. Increasing ambient temperature resulted in a significant decrease in dough and working and setting times for both cements (p = 0.038 - < 0.001). At each working time point and temperature, cement A showed significantly more intrusion than cement B (p = 0.044 - < 0.001). There was no effect of temperature on intrusion depth regardless of working time to implantation for either cement with the exception of cement B when comparing 60 versus 70°F at 0% working time (p = 0.004). Both cements showed a significant decrease in intrusion as time to implantation increased (p < 0.001). In conclusion, there are large inherent differences in properties of commercially available cements, and these properties are affected by such variables as time to implantation and ambient temperatures. An understanding of these properties may aid the surgeon in optimizing surgical outcomes.
