Reconstruction of cranial bone defects using a quick-setting hydroxyapatite cement and absorbable plates.

We examine the 6-month histology of a quick-setting hydroxyapatite cement (Mimix), with and without absorbable plates (LactoSorb), after placement in critical size defects made in the skull of 20 New Zealand white rabbits. Two 10-mm-diameter parietal defects were made in each rabbit. One defect was placed on each side of the sagittal suture. In 10 animals, the left defect was filled with Mimix alone, and in the other 10, an absorbable plate was placed across the base of the left defect before Mimix placement. The right-sided defect served as a control in all animals, with no material placed in or across this defect. The rabbits were killed 6 months postoperatively. A bone pathologist performed histologic examinations of the specimens looking specifically for evidence of inflammatory reaction and bone formation. There was no inflammation around the dura or any other negative histologic reaction in either the study groups or the control. Growth of new bone into the Mimix was found along the periphery in all specimens. We found no migration or displacement of the Mimix from any of the calvarial defects.