Effects of a local single dose administration of growth hormone on the osseointegration of titanium implants.

BACKGROUND: The aim of the present study was to evaluate the effect of different concentrations of growth hormone (GH) on endosteal implant's surface at the early stages of osseointegration. MATERIAL AND METHODS: Sixty tapered acid-etched titanium implants were divided into four groups: i) Collagen, used as a control group; and three experimental groups, where after collagen coating, GH was administered directly to the surface in varying concentrations: ii) 0.265 mg, iii) 0.53 mg, and iv) 1 mg. Implants were placed in an interpolated fashion in the anterior flange of C3, C4 or C5 of 15 sheep with minimum distance of 6 mm between implants. After 3-, 6- and 12-weeks of healing samples were harvested, histologically processed, qualitatively and quantitatively assessed for bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). RESULTS: Statistical analysis as a function of time in vivo and coating resulted in no significant differences for BIC and BAFO at any evaluation time point. Histological evaluation demonstrated similar osseointegration features for all groups with woven bone formation at 3 weeks and progressive replacement of woven for lamellar bone in close contact with the implant surface and within the implant's threads. CONCLUSIONS: A single local application of growth hormone to the surface of titanium implants did not yield improved implant osseointegration independent of healing time.

Dental Implant Placement with Simultaneous Anterior Maxillary Reconstruction with Block and Particulate Fresh Frozen Allograft Bone: A Case Report with 24-Month Follow-Up Data.

Fresh frozen allograft bone is routinely used in orthopedic surgery for the reconstruction of large bone defects, and its use in oral and maxillofacial surgery is increasing. The purpose of this case was to demonstrate the installation of dental implants and the use of fresh frozen bone for reconstruction of anterior maxilla in the same surgery. This case report presents the insertion of dental implants followed immediately by a placement of fresh frozen allograft in block and particle for a reconstruction of atrophic anterior maxillary in the same surgery. Ten months subsequent to this procedure, provisional fixed prosthesis was installed on the implants. Four months later (postoperative month 14), the final fixed prosthesis was installed and the clinical success was observed. The insertion of dental implants followed immediately by a placement of fresh frozen allograft is a safe and efficient process that results in the successful return of dental function and aesthetic rehabilitation for the patient.

L-PRP diminishes bone matrix formation around autogenous bone grafts associated with changes in osteocalcin and PPAR-γ immunoexpression.

Leucocyte- and platelet-rich plasma (L-PRP) is an autogenous platelet concentrate enriched with leukocytes that releases various growth factors responsible for the proliferation, regulation, and differentiation of mesenchymal cells during wound healing. Since the bone and medullary tissue are contiguous and share the same origin, this study evaluated the effect of L-PRP on the repair of calvaria bone using histomorphometric analysis of the newly formed bone, and compared the results in the presence of osteocalcin (OC) and peroxisome proliferator-activated receptor gamma (PPAR-γ) detected by immunohistochemistry. Artificial circular bone defects (5mm diameter) were produced in the calvaria of 42 rats. The defects were treated with autograft, autograft combined with L-PRP, or without grafting material (sham). The animals were euthanized at 15 or 40 days postsurgery (n=7 in each group). Data obtained were analyzed by Student-Newman-Keuls test for histomorphometric and immunohistochemical interpretation. The development of bone matrix was significantly less in the defects treated with L-PRP, while the medullary area composed of fatty cells was larger. This coincided with the minor expression of OC and expressive presence of PPAR-γ. These results suggest that L-PRP may impair osteoneogenesis and alter the ratio of differentiation between bone matrix and fatty cells, increasing the medullary tissue.

Bone healing in critical-size defects treated with platelet-rich plasma activated by two different methods. A histologic and histometric study in rat calvaria.

BACKGROUND AND OBJECTIVE: The purpose of this study was to analyze histologically the influence of platelet-rich plasma (PRP) coagulated with two different activators on bone healing in surgically created critical-size defects (CSD) in rat calvaria. MATERIAL AND METHODS: Forty-eight rats were divided into three groups: C, PRP-C and PRP-T. An 8 mm diameter CSD was created in the calvarium of each animal. In group C, the defect was filled by a blood clot only. In groups PRP-C and PRP-T, the defect was filled with PRP activated with either calcium chloride or thromboplastin solution, respectively. Each group was divided into two subgroups (n = 8 per subgroup) and killed at either 4 or 12 weeks postoperatively. Histologic and histometric analyses were performed. The amount of new bone formed was calculated as a percentage of the total area of the original defect. Percentage data were transformed into arccosine for statistical analysis (analysis of variance, Tukey's post hoc test, p < 0.05). RESULTS: No defect completely regenerated with bone. Group PRP-C had a statistically greater amount of bone formation than groups C and PRP-T at both time points of analysis. No statistically significant differences were observed between groups C and PRP-T. CONCLUSION: It can be concluded that the type of activator used to initiate PRP clot formation influences its biological effect on bone healing in CSD in rat calvaria.