A preliminary report on the effect of dimeric rhGDF-5 and its monomeric form rhGDF-5C465A on bone healing of rat cranial defects.

INTRODUCTION: The purpose of the study was to compare the efficacy on rat skull defects of two bone growth factors derived from the GDF-5 family. MATERIAL AND METHODS: The study was conducted on 17 adult Wistar rats. On each animal, two symmetrical 6-mm wide, full-thickness, skull defects were carried out in the parietal regions. In 15 out of 17 animals, both experimental defects were filled by the implants. In the group I (n=2), both defects were left empty for control. The 15 other rats were divided into 3 groups: In group II (n=5), a collagen sponge was implanted. In group III (n=5), a collagen sponge impregnated with rhGDF-5 (the genuine dimeric form) was implanted. In group IV (n=5), a collagen sponge impregnated with rhGDF-5C465A (a monomeric form of GDF-5) was implanted. All animals were sacrificed at 8 weeks. The harvested specimens were processed for contact radiography and standard histological examination. The quantitative results were assessed with a semi-quantitative histological scoring system. RESULTS: One animal in the group II was excluded because it died of unknown reasons. In group I, no bone healing was observed in the defects. In group II, no bone healing was observed in 4 out of 10 defects, and partial bone healing was observed in 5 out of 10 defects. In group III, partial bone healing was also observed in 3 out of 8 defects and complete bone healing in 4 out of 8 defects. In group IV, partial bone healing was observed in 8 out of 10 defects and complete bone healing in 2 out of 10 defects. CONCLUSION: Bone healing was improved in all treated groups. Further studies are necessary to determine the optimal formulation of these composite implants.

Histological findings of long-term healing of the experimental defects by application of a synthetic biphasic ceramic in rats.

Calcium phosphate ceramics are generally biocompatible and can develop interactions with human recipient bone. Therefore, they can be widely used in the field of periodontology and dentistry. The purpose of this investigation was to assess the long-term histological bone healing results of experimentally created critical size parietal bone defects in rats. Twelve Wistar rats were used in this investigation. Two 6-mm wide, symmetrical, and circular critical size defects were created in each parietal bone of the animals. While the right defects filled with granular implant (Ceraform), the symmetrical defects were taken as controls. Eighteen months after implantation, rats were killed and defects including the biomaterial with surrounding bone was taken for histological examination. Serial histological sections were cut across the defects and stained for the histological analysis. Both control and Ceraform implanted regions contained dense collagenous tissue. In the implantation site, multinuclear giant cells were observed around the material. On the other hand, there were no necrosis, tumour, and infection in the implantation region. There was no statistical difference between the control and ceraform implanted groups when the bone formation results were compared (p > 0.05). In conclusion, the results revealed that this material is biocompatible and does enhance the new bone building despite the long-term observation period. Although this biphasic ceramic shows within the limits of the study as a less resorptive and not osteoconductive properties, it can be considered as a biocompatible bone defect filling material having a limited application alternative in dentistry and medicine.

Assessment of the effect of a biphasic ceramic on bone response in a rat calvarial defect model.

Calcium phosphate ceramics are being extensively used for orthopedic, periodontal, and dental applications. This study aimed to assess the effect of a biphasic ceramic such as Ceraform on the osteogenesis in a rat calvarial defect model. 20 Wistar rats were enrolled in the study. Two symmetrical, circular, and 5-mm-wide full thickness defects were created in the parietal bones of each animal. The left defect was left empty as a control and the right defect was filled with the particular implant material. Animals were divided into two groups, and 10 animals were sacrificed at month 3 and the rest were sacrificed at month 6. The calvarial specimens were harvested for histological examinations. Defect area samples were stained with hematoxylin-eosin and Masson Thrichrom. A semiquantitative method was used to quantify the bone regeneration. The defects were mostly filled with fibrous connective tissue (3-6 months) in the control site. A loose, fibrovascular tissue was observed at the side of ceraform implantation at month 3. By 6 month, a dense collagenous tissue was observed at the same area. Multinuclear giant cells (MNGC) were detected around the implant bed at month 3 and month 6. No necrosis, tumorigenesis, or infection was observed at the implantation site at any time. There was no statistically meaningful difference regarding bone regeneration between the two defects at each observation period (p>0.05). This study showed that Ceraform is biocompatible. However, this study indicates that biphasic ceramic do not offer any advantage over hydroxyapatite ceramics. It was also revealed that it had no effects on bone regeneration and that it seemed to be a space maintainer.

The effect of a biphasic ceramic on calvarial bone regeneration in rats.

Bioactive ceramics (calcium phosphate ceramics, hydroxyapatite ceramics) are now extensively used in oral surgery. The purpose of this study was to assess the effect of a new biphasic ceramic (Ceraform) on the osteogenesis in a rat calvarial defect model. Fifteen Wistar rats were used in this study. Two symmetrical 3-mm wide defects were created in the skull of each rat. The left defect was left empty as a control and the right defect was filled with the ceramic. The rats were sacrificed at day 30, and the calvarial specimens were processed for qualitative and quantitative histological examinations. The material exhibited no adverse effects, but no bone healing was noted either. No statistical difference regarding bone regeneration was observed between the 2 defects (P > .05). This study showed that Ceraform did not elicit any inflammatory reaction; however, it had no effect on bone regeneration, and this material seems suitable only as a space-maintaining material.