Calcium aluminate, RGD-modified calcium aluminate, and beta-tricalcium phosphate implants in a calvarial defect

Calcium aluminate (CaAl), arginine-glycine-aspartic acid-modified CaAl, and beta-tricalcium phosphate (TCP) implants were studied in a rat calvarial critical-sized defect model. The rates of newly formed bone and osteointegration were measured using 3 different methods: radiography, micro-computed tomography, and histologic examination. After 4 weeks, there was no new bone formed and no signs of osteointegration into the skull bone in the CaAl or arginine-glycine-aspartic acid-modified CaAl groups, and thick fibrous capsules were visible around the whole circumference of the implants in both groups. In the beta-TCP group, neovascularization of the implant was observed, which is consistent with the early phase of new bone formation. In addition, in the beta-TCP group, signs of implant integration into the host tissue were evident at 4 weeks. There was no soft tissue reaction around the beta-TCP implant. These observations suggest that more specific adhesion peptides may be needed to activate the bioinert CaAl implant and promote bone formation in the craniofacial skeleton.