I am a master degree candidate at Faculty of Dentistry-Cairo University,Periodontist and implantologist.
Bone is a specialized mineralized connective tissue that consists of specialized cell types including osteoblasts, osteoclasts and osteocytes and extracellular matrix. Physiologic bone remodeling consists of two main phases; the bone formation and resorption.
Abstract: The aim of this study was to establish an objective method for quantitative evaluation of bone volume change after sinus augmentation. 11 sinuses in 9 patients were evaluated by computed tomography images taken before treatment (T0), and 3 months (T1) and at least 1 year (T2) after sinus augmentation. Based on the 3D digital subtraction technique, augmented bone images were extracted and bone volumes were calculated from voxel numbers of the extracted images. The mean augmented bone volumes at T1 and T2 were 2.46 cm3 and 1.85 cm3, respectively. These bone volume changes were statistically significant and the mean bone volume change ± SE was -24.8% ± 6.1%. Loss of augmented bone was observed in all except one of the patients. The correlation coefficient between bone volume change and elapsed time was -0.64, which was statistically significant and indicated that bone resorption progressed with elapse of time after sinus augmentation. The authors' method of analysis enabled visualization of augmented bone and objective assessment of bone volume change. Within the limited number of cases, the present investigation demonstrated a significant decrease in augmented bone volume between 3 and 23 months after surgery.
Pub.: 04 May '12, Pinned: 25 Aug '17
Abstract: A sheep animal model was used to investigate the clinical behavior of autologous bone transplants after cryopreservation. The aim of the present study was to compare fresh, cryopreserved and deep-frozen bone transplants in terms of their osseointegration. We used a serum-free cryopreservation protocol with DMSO as cryoprotectant for the bone transplants, which were harvested from the iliac crest of the sheep. The bicortical iliac bone grafts were either cryopreserved or immediately frozen to -80 degrees C for 4 weeks. Four, 8, 12 and 16 weeks after the autologous transplantation of the cryopreserved, fresh or deep-frozen bone transplants to the contralateral iliac crest, the animals were sacrificed and the bone specimens were evaluated clinically, by staining for hematoxylin/eosin and for tartrate-resistant acid phosphatase, by quantified computed tomography, immunohistochemistry (Ki67) and polychrome sequential labeling. The best results were obtained for the fresh specimens with 83% bone healing compared with 75% (cryopreserved bone) and 50% (deep frozen bone). All parameters indicate that bone formation and remodeling processes take place in fresh and cryopreserved transplants. The deep-frozen specimens displayed no fluorochrome uptake in the sequential labeling. These findings indicate that osseointegration of the fresh transplants was the most successful and that osteogenic effects in fresh and cryopreserved transplants are located in the surface area, whereas only the osteoconductive effects are important in the center of the transplants. Thus, cryopreservation is a useful method for the clinical routine because it keeps the osteogenic cells viable, making it superior to deep freezing of abundant bone.
Pub.: 07 Jan '10, Pinned: 25 Aug '17
Abstract: An insufficient quality and amount of bone often necessitate the clinical use of implants together with bone transplants. The present study describes an experimental animal model for the study of implants in bone grafts. Circular defects were made bilaterally in the tibia of 36 rabbits. The defects received either autologous cortical bone (control), demineralized bone matrix (DBM), plasma-augmented DBM or were left empty (without bone graft). In all defects a titanium implant was centrally placed and anchored in the opposite cortex. Evaluation with light microscopic morphometry showed that the insertion of a threaded titanium implant centrally in a cortical defect was followed by a spontaneous healing of the defect after 6 mon. After 6 wk, all implants in cortical grafts were well integrated with a significantly higher bone-to-implant contact than in the DBM and plasma-augmented groups. After 6 mon, all experimental groups had a mean bone area within the threads ranging between 69% and 80% and a mean bone-to-implant contact between 31% and 42%. The results from the present study indicate that the model allows comparative studies on the early formation, resorption and remodelling of bone around implants after modification of implant, graft and host properties.
Pub.: 01 Sep '98, Pinned: 25 Aug '17
Abstract: Bone is unique in connective tissue healing because it heals entirely by cellular regeneration and the production of a mineral matrix rather than just collagen deposition known as scar. This article discusses the cellular, tissue, and organ levels in each of the following sections--skeletal embryology, normal bone, examples of abnormal bone, and bone graft healing--as they relate to the jaws and the craniofacial skeleton.
Pub.: 20 Dec '07, Pinned: 25 Aug '17
Abstract: Rodrigo Carlos da Silva, Viviane Rozeira Crivellaro, Allan Fernando Giovanini, Rafaela Scariot, Carla Castiglia Gonzaga, João César Zielak Annals of Maxillofacial Surgery 2016 6(1):9-14 Objective: To evaluate, through radiographic and histological analysis, the tissue reaction induced by a biomaterial based on deproteinized bovine bone matrix (DBBM) in the muscle of sheep. sMaterials and Methods: Sixteen sheep were used. The animals underwent surgery to insert polyethylene tubes containing the biomaterial in the muscle of the lower back (ectopic site) and were euthanized after 3 and 6 months. Each sheep received three tubes: Group 1 - sham group (negative control - tube without biomaterial), Group 2 - particulate autogenous bone (positive control), and Group 3 - DBBM biomaterial (GenOx Inorg). The material removed was evaluated by radiographic, macroscopic, and microscopic analysis, descriptively. Results: Macroscopic analysis showed that Group 3 had a greater tissue volume maintenance. Microscopic analysis indicated that Group 1 had a higher concentration of dense, thin collagen fibers (3 and 6 months); in Group 2, there was a decrease in the inflammatory process and the deposition of dense, thin collagen fibers (3 and 6 months); in Group 3, the presence of a dense connective tissue was noted, in which the DBBM particles (3 months) were found. On the periphery of these particles, a deposition of basophilic material was found, indicating the formation of mineral particles and the formation of tissues with osteoid characteristics (6 months). Conclusion: Based on the results obtained, it can be concluded that the biomaterial based on DBBM led to the formation of tissue with similar characteristics to an osteoid matrix in a postoperative period of 6 months. However, none of the groups evaluated showed ectopic bone neoformation.
Pub.: 12 Jul '16, Pinned: 25 Aug '17
Abstract: To investigate the influence of maturation timing upon histological, histomorphometric and clinical outcomes when deproteinized bovine bone mineral (DBBM) was used as a sole biomaterial for staged maxillary sinus floor augmentation (MSFA).Patients with a posterior edentulous maxillary situation and a vertical bone height ≤ 4 mm were included in this study. A staged MSFA was carried out. After MSFA with DBBM as a sole grafting material, biopsy cores were harvested with simultaneous implant placement followed by a healing period of 5, 8, and 11 months, respectively. Micro-CT, histologic and histomorphometric analyses were performed.Forty-one patients were enrolled and 38 bone core biopsies were harvested. Significantly greater BV/TV was observed between 5- and 8-month healing from micro-CT analysis. Histomorphometric analyses showed the ratio of mineralized newly formed bone increased slightly from 5 to 11 months; however, no statistically significant difference was reached (p = .409). Residual bone substitute decreased from 37.3 ± 5.04% to 20.6 ± 7.45%, achieving a statistical significant difference from of 5 up to 11 months (p < .01). Moreover, no implant failure, biological or technical complication occurred after 12-month follow-up of functional loading.DBBM utilized as sole grafting material in staged MSFA demonstrated to be clinically effective regardless of the healing period. Histomorphometrical and micro-CT assessments revealed that at later stages of healing (8 and 11 months) there is a higher proportion of newly-bone formation compared to earlier stages (5 months). Moreover, the longer the maturation period, the substantially lesser remaining biomaterial could be expected. Even though, these facts did not seem to negatively impact on the implant prognosis 1-year after loading.
Pub.: 16 Nov '16, Pinned: 25 Aug '17