Differential scanning calorimetric study of acrylic resin powders used in dentistry.

The thermal behavior of eight dental acrylic resin powders was studied using differential scanning calorimetry (DSC). In addition, high performance liquid chromatography was performed to supplement the DSC analysis. The HPLC analysis revealed that the contents of residual monomers and benzoyl peroxide (BPO) in the powders were 0.01-0.97 mass% and 0.25-1.28 mass%, respectively. All the resin powders produced one broad exothermic peak, while a mixture of BPO and PMMA powders generated two peaks. One peak pattern was assigned to the decomposition of BPO included within the polymer particles. The results suggested that BPO was present inside the particles and little BPO was mixed into the resin powders. Moreover, the present study demonstrated a unique useability of DSC in characterizing resin powders.