Biological response to ß-tricalcium phosphate/calcium sulfate synthetic graft material: an experimental study.

PURPOSE: The aim of this study was to evaluate the effect of a biphasic synthetic bone graft material composed of ß-tricalcium phosphate (ß-TCP) and calcium sulfate (CS) in 12 New Zealand rabbits. MATERIALS AND METHODS: A circular bicortical critical-size cranial defect was created in each of 12 rabbits. The defects were grafted with ß-TCP/CS. Animals were euthanized at 3 and 6 weeks. Harvested tissue specimens were evaluated histologically and histomorphometrically. Parameters associated with new bone formation and graft resorption were measured and calculated. The results were statistically analyzed using the Mann-Whitney test. RESULTS: Our data demonstrated the biocompatibility of synthetic ß-TCP/CS, as no inflammatory response was observed, and no fibrosis was developed between the graft particles and the newly formed bone. Moreover, ß-TCP/CS acted as an osteoconductive scaffold that allowed a significant bone regeneration and graft biodegradation with time. CONCLUSION: In this animal model, synthetic ß-TCP/CS proved to be a biocompatible, osteoconductive, and bioresorbable bone graft substitute.

Experimental study of the effect of autologous platelet-rich plasma on the early phases of osteoinduction by allogenic demineralized bone matrix.

PURPOSE: To evaluate the effect of autologous platelet-rich plasma (PRP) on the early phases of osteoinduction by allogenic demineralized bone matrix (DBM) in rabbit intramuscular positions. MATERIALS AND METHODS: Allogenic DBM was produced from bones of 3 healthy rabbits. In each of 6 experimental animals, 0.3 mL autologous PRP was prepared and 2 muscle pouches were created, where 250 mg DBM + PRP (experimental sites) and 250 mg DBM without PRP (control sites) were randomly implanted. Animals were euthanized 3 weeks postoperatively. RESULTS: Histologic examination revealed uneventful healing in all cases, whereas remineralization of the periphery of the bone graft particles was a constant finding. In both control and experimental sites, fibroblasts and other mesenchymal cells (probably osteoprogenitor cells and preosteoblasts) were observed. The main histological difference was the recolonization of the empty lacunae of the bone graft particles by osteocytes at the control sites. The degradation of the graft at the control sites was statistically significantly quicker, although a statistically significant difference regarding the amount of the newly formed fibrous connective tissue was not observed. CONCLUSION: The present study demonstrated that in this experimental model, the addition of PRP to DBM had a negative effect on the early phases of osteoinduction at 3 weeks of observation.

Osseous Healing in Surgically Prepared Bone Defects Using Different Grafting Materials: An Experimental Study in Pigs.

Regeneration of large jaw bone defects still remains a clinical challenge. To avoid incomplete bone repair, bone grafts have been advocated to support the healing process. This study comparatively evaluated new bone formation among a synthetic graft substitute, a human bone derivative, and a bovine xenograft. Materials were placed in 3 out of the 4 bone cavities, while 1 deficit was left empty, serving as a control, in mono-cortical defects, surgically prepared in the porcine calvaria bone. Animals were randomized in 2 groups and euthanized at 8 and 12 weeks. Harvested tissue specimens were qualitatively evaluated by histology. New bone formation was quantitatively measured by histomorphometry. Maximum new bone formation was noticed in defects grafted with beta-tricalcium phosphate b-TCP compared to the other bone substitutes, at 8 and 12 weeks post-surgery. Bovine and human allograft induced less new bone formation compared to empty bone cavity. Histologic analysis revealed that b-TCP was absorbed and substituted significantly, while bovine and human allograft was maintained almost intact in close proximity with new bone. Based on our findings, higher new bone formation was detected in defects filled with b-TCP when compared to bovine and human graft substitutes.

Osteogenic activity of ß-tricalcium phosphate in a hydroxyl sulphate matrix and demineralized bone matrix: a histological study in rabbit mandible.

Currently, in oral and maxillofacial surgery, there is a clinical need for efficient bone grafting materials, and various efforts are being made to improve materials used as bone substitutes to facilitate faster and denser bone regeneration. The purpose of this study was to evaluate in vivo the osteogenic potential of synthetic ß-tricalcium phosphate in a hydroxyl sulphate matrix (ß-TCP/HS) and human demineralized bone matrix (DBM) putty. Sixteen New Zealand White rabbits were used. In each animal, two bone defects (8 mm length × 3 mm width × 3 mm depth) were created in the left and right regions of the mandible, respectively. The defect on one side, chosen randomly, was filled with ß-TCP/HS (group A) or DBM putty (group B), while the defect on the opposite side was left unfilled in order to serve as a control site. Two animals in each group were sacrificed at the end of the 1st, 3rd, 5th and 6th week after surgery, respectively, and the osteotomy sites were processed for histological evaluation. Our findings confirmed that ß-TCP/HS and human DBM putty possess osteogenic activity and can support new bone formation, although at a slower rate than the spontaneous healing response, in rabbit mandibular osseous defects.

Vascular fractal dimension and total vascular area in the study of oral cancer.

BACKGROUND: Microvessel quantification has been studied extensively as a factor reflecting angiogenesis in various malignant tumors. The aim of our study was to evaluate the vascular fractal dimension and the immunohistochemically positive total vascular area in oral cavity carcinomas in order to assess their potential value as factors reflecting angiogenesis. METHODS: Histologic sections from 48 carcinomas and 17 nonmalignant mucosa specimens were evaluated by image analysis using fractal analysis software. Total vascular area was also quantified. RESULTS: Carcinomas presented higher mean values of vascular fractal dimension and total vascular area compared to normal mucosa. The difference for the vascular fractal dimension was statistically significant. CONCLUSIONS: This study provides evidence that vascular fractal dimension could be used as a reliable factor reflecting angiogenesis in oral squamous cell carcinoma and that there are several statistically significant correlations among total vascular area, vascular fractal dimension, nuclear size, and clinicopathologic factors.