Composite acrylic cement with added hydroxyapatite: a study of the polymerization temperature.

Varying percentages (0 to 50%) of crystalline hydroxyapatite (HA) in powder form were added to ordinary acrylic cement (PMMA). The exothermic peak of the polymerization reaction and the setting time of this compound cement were investigated. Its mechanical properties are far superior to those of ordinary cement. The addition of small percentages of HA to acrylic cement produces a sharp fall in the exothermic polymerization peak; it also increases the setting time, although this remains within time limits that are only slightly greater than those for ordinary cement.