Correlation of platelet growth factor release in jawbone defect repair--a study in the dog mandible.

BACKGROUND Platelet concentrate/platelet-rich plasma (PRP) has been studied extensively in various experimental models and there is some agreement among workers to its early effect in bone regeneration and healing. We have earlier showed in vitro that titanium in whole blood activates the thrombogenic response to a higher degree than PRP and that a fluoridated test surface augmented the effect compared with control. PURPOSE We designed this study to evaluate the effect of PRP and whole blood on bone regeneration in a dog implant defect model and, in addition, the effect of a test surface modified in hydrofluoric acid. A correlation attempt between platelet count, release of growth factors, and bone regeneration was made. MATERIALS AND METHODS Six dogs were used and simultaneously with the experimental surgery and implant installation, autologous PRP was prepared. Defects were prepared (6 mm in diameter and 5 mm deep), and implants were installed (TiO2 gritblasted and hydrofluoric acid treated [test] or TiO2 gritblasted [control], 5 mm in diameter and 9 mm long) in defects filled with either PRP or whole blood. Randomization of sides between PRP and whole blood, and sites for test and control implants were made. Blood samples were collected from PRP and whole blood. The dogs were killed after 5 weeks of healing, and samples with implants and surrounding bone were collected and processed for analysis. Enzyme linked immunosorbent assays were used for detection of growth factors in PRP. RESULTS The mean increase of platelet count was 424% in PRP. A correlation for platelet counts and transforming growth factor β was found in each dog (r(2) = 0.857). Approximately 50% of the region of interest (ROI) in the defects was filled with new bone after 5 weeks. No difference could be observed in ROI by using PRP or whole blood in the defects regarding new bone formation, bone in contact with implant, or distance to first bone contact. However, the fluoridated implants exhibited more new bone formation (p = .03) compared with control, regardless of comparing PRP or whole blood, and also displayed a shorter distance from first bone contact to the margin of the bone envelope (p = .05). CONCLUSIONS Platelet concentrate/PRP failed to show more new bone regeneration in a peri-implant defect model compared with whole blood. Implants treated with hydrofluoric acid displayed higher percentages of bone fill in the defect.