Effect of Bio-Oss with or without platelet-derived growth factor on bone formation by "guided tissue regeneration" : a pilot study in rats

To investigate the effect of Bio-Oss with and without the local application of recombinant human platelet-derived growth factor (rhPDGF-BB) on bone formation under Teflon capsules. MATERIALS AND METHODS: Eight male, 6-month-old, Wistar strain rats were used in the study. In each animal, the lateral aspect of the mandibular ramus was exposed and small perforations were produced in the bone. A rigid, non-porous hemispherical teflon capsule (diameter 7 mm) was placed on the ramus in both sides of the animals. The capsule placed on the one side of the jaw was filled with Bio-Oss granules soaked in a solution of PDGF-BB (20 microg/capsule) and autogenous blood prior to placement. The capsules placed on the other side of the jaw were filled with Bio-Oss granules soaked in autogenous blood only (controls). Four rats were sacrificed after 3 months and the remaining four after 5 months. Undecalcified sections containing the capsule and surrounding tissues were prepared and analysed in the microscope. RESULTS: Histologic analysis revealed limited amounts of bone formation. Most of the space underneath the capsules was occupied by Bio-Oss particles surrounded by fibrovascular connective tissue. Given the small sample size statistical analysis was not possible, however, the mean amount of mineralized new bone in the control group (20.8%) appeared to be larger than that in the test group (6.7%). After 5 months the amount of newly formed bone appeared similar in the two groups (23.0% test, 26.0% controls). The Bio-Oss particles occupied between 31.4% and 41.1% of the capsule area at 3 months and between 34.0% and 34.7% at 5 months. Only particles adjacent to the mandibular ramus were incorporated in newly formed bone. CONCLUSION: Limited bone formation was present in the capsules grafted with Bio-Oss with or without the growth factor