The efficacy of various alloplastic bone grafts on the healing of rat calvarial defects

The objective of this study was to determine the relative efficacy of currently available alloplastic bone repair materials in the healing of rat calvarial defects histologically, histomorphometrically and biochemically. A representative material was selected from six major classes of bone repair materials and placed in 4 mm diameter calvarial defects of 6-week-old male Sprague-Dawley rats (five animals in the control and each of the six experimental groups). The outcomes were assessed after 2 months for alkaline phosphatase (ALP) activity and after 4 months of healing for histomorphometry. The tested alloplastic implant materials did not significantly increase ALP activity or the amount of new bone formation in the healing of rat calvarial defects relative to controls (P > 0.05). However, when the implant material itself was included in the analysis, significant differences were observed (P < 0.05). Additionally, the tested materials varied in their ability to bridge the bony defect. These data suggest that the rate of bone formation cannot be increased beyond control levels, rather the advantage of implant materials may be in their efficiency in filling the defect through incorporation of the material into the healing site and rapidly bridging the wound.