The effect of human freeze dried corticocancellous block onlay graft on bone formation in rat calvarium

The aim of this study was to investigate the effect of an onlay graft of human freeze dried corticocancellous bone block (FDBB) on bone formation and the added effects of collagen membrane (CM) in rat calvarium. Thirty male Sprague-Dawley rats were treated with either collagen sponge (CS), FDBB or FDBB with CM. FDBBs were placed on the calvarium surface with the CM covered or not. Rats were sacrificed at 2 and 8 weeks after surgery for histologic and histomorphometric analysis. At each period, total augmented area (TA; mm²), new bone area (NB; mm²), and bone density (BD; %) were measured. In the FDBB and the FDBB/CM group, new bone formation began at the lateral and inferior margins of the grafted block and projected into the central region of the recipient-graft interface. The cancellous portion of the graft underwent increased resorption with time. FDBB showed a significant decrease in the TA between 2 and 8 weeks (p<0.05), regardless of combined use of the CM. NB significantly increased in FDBB between 2 and 8 weeks (p<0.05), and the CM showed significant additional effect on new bone formation at 8 weeks (p<0.05). BD significantly increased in FDBB between 2 and 8 weeks (p<0.05). Within the limits of the present study, it was concluded that the maintenance of volume was achieved with onlay grafting of FDBB in early healing period to show new bone apposition onto the rat calvarial surface. In addition, using of CM improved new bone formation within in the grafted area.