Use of a mineralized collagen membrane to enhance repair of calvarial defects in rats.

The aim of the present study was to evaluate mineralized collagen membranes for enhancement of bone regeneration in calvarial defects. Forty adult female Sprague-Dawley rats received calvarial full thickness defects with a diameter of 8 mm. In 20 animals, the defects were covered with a mineralized collagen membrane, and 20 animals served as controls. After 6, 13, 26 and 52 weeks, bone regeneration was evaluated using undecalcified thick-section histometry. There was no clear enhancement of bone regeneration during the first 26 weeks after the operation. Bone regeneration underneath the membrane produced consistently thicker bone, albeit without statistical significance. Accumulation of membrane material occurred in the center of the defects surrounded by multinuclear giant cells during early stages of healing. After complete resorption of the membrane, significantly increased bone formation was seen after 52 weeks in the defects that had received membrane coverage. It was concluded that mineralization in the present form did not increase mechanical strength of the membrane to prevent interference of the membrane with bone regeneration in the defect. The reason for the increase in bone formation after resorption of the membrane after 26 weeks remains to be clarified.