Effects of calcium phosphate nanocrystals on osseointegration in irradiated animal

Objectives: To evaluate the effect of discrete calcium phosphate nanocrystal modification of implant on osseointegration in irradiation compromised animal model. Materials and Methods: Sixteen adult New Zealand White rabbits were randomly divided into NanoTite (discrete calcium phosphate nanocrystal modification) and OsseoTite (control) groups. The left leg of rabbits received 15Gy radiation. One week after radiation, two implants were placed in the irradiated leg of each rabbit. Implant stability quotient (ISQ) were measured immediately. Four rabbits in each group were sacrificed at 4 week and 12 week respectively. ISQ was measured again before sacrifice. Osseointegration was assessed using micro-CT with the ratio of bone volume to total volume (BV/TV). Results: Fourteen animals completed experiment. No inflammation and mobility were detected. There was no statistical difference in ISQ values at week 4 between two groups. At week 12, NanoTite group showed a significantly higher ISQ value than the control group. BV/TV in NanoTite group was significantly higher than that in the control group at week 4 and week 12. Conclusion: The discrete calcium phosphate nanocrystal modification on the implant surface can enhance the osseointegration in the irradiated rabbit model.