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

Aim: 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 μg/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.