Effects of coating of rhBMP-2 and rhPDGF-BB to Titanium implant

Objectives: To examine the effect of recombinant rhBMP-2 and rhPDGF-BB coated onto anodized implant to stimulate local bone formation and osseointegration. Methods: Six young male adult Beagle dogs were used. A crestal area was leveled on both sides without exposing cancellous bone. Three anodized implants (Length 8 mm, Diameter 4 mm; Cowellmedi Co, Busan, Korea) were placed 5 mm into the mandibular alveolar ridge on either side, to make 3mm supra-alveolar defect model. Thirty-six implants were divided into 4 groups (Nine in each group): Group I (rhBMP-2 750µg/ml concentration), Group II (rhPDGF-BB 75µg/ml), Group III (rhBMP-2 mixed with rhPDGF-BB) and Control (uncoated). Radiological examinations were performed immediately, 4 and 8 weeks after implant placement. The amount of bone augmentation was evaluated by measuring the distance from the uppermost point of the cover screw to the marginal bone. The animals were sacrificed after 8 weeks healing periods, histological specimens were made using Goldner Trichrome staining method. The ratio of bone-to-implant contact and the area of bone formation on intra-threads of the implant were measured. Statistical analysis was performed using one-way ANOVA (SPSS Inc, version 17.0) and multiple comparison tests (95% confidence level). Results: At radiographic finding after 8 weeks healing period, Group I and III exhibited significant vertical bone formation compared with the control and Group II, 0.88±0.94 (Group I) versus 0.68±0.64 (Group III) versus -0.42±0.58 (Group II) versus -0.52±0.64 (control) mm, respectively. There was a significant difference between the groups with rhBMP-2 and without rhBMP-2 in bone level change (p < 0.05). In histometric analysis, the groups with rhPDGF-BB exhibited significant higher BIC ratio compared with other groups (p < 0.05). Conclusion: Within the limits of this study, the results suggest that by coating with rhBMP-2 and rhPDGF-BB, osseointegration can be improved and vertical bone growth promoted.