Temperature changes in a cemented mandibular endoprosthesis: in vitro and in vivo studies

Using polymethylmethacrylate (PMMA) cement in cemented endoprostheses may cause heat necrosis and prosthesis failure due to the highly exothermic reaction. This study determined the magnitude and duration of temperature change during the cementation of a mandibular endoprosthesis in an in vitro and in vivo Macaca fasicularis model. In the in vivo study the median maximum temperature (T(max)) around the mandible-prosthesis unit (MPU) was 31.0°C with the peak T(max) at hole 1 (1mm from stem). The in vitro study recorded a lower T(max) and indicated a trend that increased spacing (groove) around the prosthesis results in a higher T(max). All the T(max) MPU measurements were lower than normal body temperature (38°C). In the in vivo study the median maximum temperature change (T(maxΔ)) was 1.8°C; in the vitro study, the T(maxΔ) of the 4mm groove width was significantly higher than all others. Temperature increases were transient, with the temperature returning to baseline a median of 6.0min after T(max). Histological analysis showed surrounding tissue at the cement-bone interface with mild inflammation. Within the parameters tested, there was minimal risk of thermal damage. The temperature changes were influenced by the quantity of cement used and the distance from the prosthesis stem.