Dental implant may be immediately placed in postextraction socket which has alveolar bone defect. The purpose of this study was to compare the bone regeneration and bone quality around defects adjacent to implants that were placed into extraction sockets according to EFEB, GTAM barrier and GTAM barrier with DFDB. Mandibular P2, P3 and P4 were extracted bilaterally in dogs, and buccal defects were created about 4mm in depth and 3.3mm in width. Screwed pure titanium implants, 3.8mm in diameter and 10mm in length, were placed into the extraction sockets. The experimental groups were divided into four groups : the G group was covered with a GTAM barrier on the defective area, the D+G group was filled with DFEB and covered with a GTAM barrier, the D group was filled with DFDB only and the control group was sutured without any special treatment on the defective area. The experimental animals were killed after 12 weeks and specimens were prepared for light microscopic evaluation and fluorescent dyes were administered daily for 2 weeks after implantation, and injected on the 4th and 11th week for fluorescent microscopic examination to observe new bone formation and bone remodeling. The new Bone height of the buccal defect was measured and compared with the another for bone gain and the removal torque for the implant was measured for the comparison of bone density and bone-implant osseointegration. Results obtained were as follows : 1. Experimental groups showed bone regeneration in oder from D+G, G, D group and control. D+G and G group was significantly from D group and control(P<0.01). 2. In the defective area of control the regenerated alveolar bone showed poorly developed lamellated structure and fibrous tissue intervention into the bone-implant interface but the others showed well developed lamellated structure and osseointegration. 3. All implant groups showed no significant difference in the removal torque for implant(P>0.05) These results suggest that immediate implants placed in defective sockets were successfully osseointegrated and utilizing placed in defective sockets were successfully osseointegrated and utilizing not only the combination of GTAM and DFDB but also only the GTAM was favorable for the predictable regeneration of the defective area.
Animals ; Bone Density ; Bone Regeneration* ; Bone Remodeling ; Dental Implants ; Dogs ; Fluorescent Dyes ; Osseointegration ; Osteogenesis ; Regeneration ; Titanium ; Torque

OBJECTIVE: Periodontal ligament fibroblasts have an ectomesenchymal origin and are thought to play a crucial role for not only homeostasis of periodontal tissues but also bone remodeling, wound healing and regeneration of tissues. Recently, it has been reported that UNC-50 is not expressed in gingival fibroblasts but in PDL fibroblasts. The purpose of this study was to examine the expression of UNC-50 and osteocalcin in the periodontium after application of intermittent force. METHODS: Twelve rats had 40 grams of mesially-directed force applied at the upper molar for 1 hour/day. Four rats were sacrificed at 1, 3 and 5 days. Immunohistochemical localization of UNC-50 and osteocalcin antibody was carried out. The results showed apposition of new cellular cementum and a slight increase in periodontal space at the tension side. RESULTS: Strong UNC-50 expression was observed in the differentiating cementoblasts close to PDL fibroblasts in the tension side whereas it was barely expressed at the compression side. Expression was strong at day 3, and decreased at day 5. Osteocalcin immunoreactivity expression was strong in differentiating cementoblasts at the tension side. CONCLUSION: It can be suggested that UNC-50 is related to the differentiation of cementoblasts, and may be responsible for the molecular event in PDL cells under mechanical stress.
Animals ; Bone Remodeling ; Dental Cementum ; DNA* ; Fibroblasts ; Homeostasis ; Molar ; Osteocalcin ; Periodontal Ligament ; Periodontium ; Rats* ; Regeneration ; Stress, Mechanical ; Wound Healing

The current interest in periodontal tissue regeneration has lead to research in bone graft, root surface treatments, guided-tissue regeneration, and the administration of growth factors as possible means of regenerating lost periodontal tissue. Several studies have shown that a strong correlation between platelet-rich plasma and the stimulation of remodeling and remineralization of grafted bone exists, resulting in a possible increase of 15-30% in the density of bone trabeculae. The purpose of this study was to study the histopathological correlation between the use of platelet-rich plasma and a bone xenograft used in conjunction with a non-resorbable guided-tissue membrane, e-PTFE, compared to a control group with regards to bone regeneration at the implant fixture site. Implant fixtures were inserted and graft materials placed into the left femur of in the experimental group, while the control group received only implant fixtures. In the first experimental group, platelet-rich plasma and BBP xenograft were placed at the implant fixture site, and the second experimental group had platelet-rich plasma, BBP xenograft, and the e-PTFE membrane placed at the fixture site. The degree of bone regeneration adjacent to the implant fixture was observed and compared histopathologically at 2, 4, and 8 weeks after implant fixture insertion. The results of the experiment are as follows: 1. The rate of osseointegration to the fixture threads was found to be greater in the first experimental group compared to the control group. 2. The histopathological findings of the second experimental group showed rapid resorption of BBP with subsequent new bone formation replacing the resorbed BBP. 3. The second experimental group showed new bone formation in the area adjacent to the fixture threads beginning two weeks after fixture implantation, with continued bone remodeling in the areas mesial and distal to the fixture. 4. Significant new bone formation and bone remodeling was observed in both experimental groups near the implant fixture sites. 5. The rate of osseointegration at the fixture threads was greater in the second experimental group compared to the first group, and the formation of new bone and trabeculae around the fixture site occurred after the fourth week in the second experimental group. The results of the experiment suggest that a greater degree of new bone formation and osseointegration can occur at the implant fixture site by utilizing platelet-rich plasma and bone xenografts, and that these effects can be accelerated and enhanced by concurrent use of a non-resorbable guided tissue membrane.
Bone Regeneration ; Bone Remodeling ; Dental Implants* ; Femur ; Heterografts ; Intercellular Signaling Peptides and Proteins ; Membranes ; Osseointegration ; Osteogenesis ; Platelet-Rich Plasma* ; Regeneration* ; Transplants

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases. MMPs can degrade and remodel extracellular matrix, also active or inactive many molecules attaching to matrix including receptors, growth factors and cytokines, so that injury-induced MMPs can change the extracellular environment to affect the axonal regeneration in central nervous system. In this review, with spinal cord injury (SCI) as an example we discuss the effects of MMPs on inflammation, neuronal viability, extracellular molecules, glial scar and axonal remyelination, which are all important to axonal regeneration.
Axons ; Cicatrix ; Extracellular Matrix ; Matrix Metalloproteinases ; Nerve Regeneration ; Neuroglia ; Spinal Cord Injuries

OBJECTIVES: To validate a critical-size mandibular bone defect model in miniature pigs. MATERIALS AND METHODS: Bilateral notch defects were produced in the mandible of dentally mature miniature pigs. The right mandibular defect remained untreated while the left defect received an autograft. Bone healing was evaluated by computed tomography (CT) at 4 and 16 weeks, and by micro-CT and non-decalcified histology at 16 weeks. RESULTS: In both the untreated and autograft treated groups, mineralized tissue volume was reduced significantly at 4 weeks post-surgery, but was comparable to the pre-surgery levels after 16 weeks. After 16 weeks, CT analysis indicated that significantly greater bone was regenerated in the autograft treated defect than in the untreated defect (P=0.013). Regardless of the treatment, the cortical bone was superior to the defect remodeled over 16 weeks to compensate for the notch defect. CONCLUSION: The presence of considerable bone healing in both treated and untreated groups suggests that this model is inadequate as a critical-size defect. Despite healing and adaptation, the original bone geometry and quality of the pre-injured mandible was not obtained. On the other hand, this model is justified for evaluating accelerated healing and mitigating the bone remodeling response, which are both important considerations for dental implant restorations.
Autografts ; Bone Regeneration ; Bone Remodeling ; Dental Implants ; Hand ; Mandible ; Swine*

The current interest in periodontal tissue regeneration has lead to research in bone graft, root surface treatments, guided-tissue regeneration, administration of growth factors, and the use of enamel matrix protein as possible means of regenerating lost periodontal tissue. Several studies have shown that a strong correlation between platelet-rich plasma and the stimulation of remodeling and remineralization of grafted bone exits, resulting in a possible increase of 15-30% in the density of bone trabeculae. The purpose of this study was to study the histopathological results and differences between the use of platelet-rich plasma and the use of enamel matrix protein(Emdogain?) about bone regeneration at the implant. Implant fixtures were inserted and graft materials placed into the left femur in the experimental group, while the only implant fixtures placed in the control group. In the first experimental group, platelet-rich plasma and xenograft were placed at the supracrestally placed implant site, and in the second experimental group, Emdogain(R) and xenograft placed at the supracrestally placed fixture site. The degree of bone regeneration adjacent to the implant fixture was observed and compared histopathologically at 2, 4, and 8 weeks after implant fixture insertion. The results of the experiment are as follows: 1. The rate of osseointegration to the fixture threads was found to be greater in the experimental group compared to in the control group. 2. The histopathological findings showed that the bone regeneration, the partial osseointegration existed at 4 weeks, and that osseointegration and bone density increaced in the experimental groups at 8 weeks. 3. The results showed that new bone formation and bone remodeling increased in the area near to the fixture in the first and second experimental groups at 8 weeks than at 4 weeks. The results showed that in the area distant from the fixture, new bone formation did not increase and bone remodeling decreased in the first experimental group at 4, 8 weeks, and that new bone formation increased in the second experimental group. 4. The histopathological findings showed that AZ deposition in the first experimental group was remarkable at 2, 8 weeks, and in the second experimental group at 2, 4, 8 weeks in the area distant from the fixture threads.
Bone Density ; Bone Regeneration* ; Bone Remodeling ; Dental Enamel* ; Dental Implants* ; Femur ; Heterografts ; Intercellular Signaling Peptides and Proteins ; Osseointegration ; Osteogenesis ; Platelet-Rich Plasma* ; Regeneration ; Staphylococcal Protein A ; Transplants

No abstract available.
Nerve Regeneration*

Spinal cord injury is a highly disabled neurological disease, and there is still a lack of effective treatments. Studies have proved that olfactory ensheathing cells are one of the ideal seed cells for promoting nerve regeneration after spinal cord injury. Olfactory ensheathing cells can promote axonal germination and elongation through secretion, interaction with astrocytes, regulation of inflammatory reaction, migration characteristics, myelination, anti-oxidation, lipid regulation and other channels. Thus olfactory ensheathing cells play the role of neuroprotection and nerve repair. In recent years, some studies have used bioengineering, tissue engineering, reprogramming and other technologies to enhance the efficacy of olfactoryensheathing cells from different aspects, thereby providing new therapeutic strategies for optimizing the cell therapy of spinal cord injury. This article will summarize the mechanism of olfactory ensheathing cells in repairing spinal cord injury, and review the progress of optimizing strategy of olfactory ensheathing cells in treating spinal cord injury recently, so as to provide new research ideas for the further developing the repair potential of olfactory ensheathing cells and optimize the cell therapy effect of spinal cord injury.
Cell Transplantation ; Humans ; Nerve Regeneration ; Spinal Cord Injuries/therapy*

The osteocyte has long been considered to be the primary mechanosensory cell in the bone. Recent evidence has emerged that the osteocyte is also a key regulator of various bone and mineral metabolism and that its regulatory effects are in part mediated through locally produced osteocyte-derived factors, such as sclerostin, receptor activator of nuclear factor-kappa B ligand (RANKL), and fibroblast growth factor (FGF)-23. Osteocytes secrete large amounts of insulin-like growth factor (IGF)-I in bone. Although IGF-I produced locally by other bone cells, such as osteoblasts and chondrocytes, has been shown to play important regulatory roles in bone turnover and developmental bone growth, the functional role of osteocyte-derived IGF-I in the bone and mineral metabolism has not been investigated and remains unclear. However, results of recent studies in osteocyte Igf1 conditional knockout transgenic mice have suggested potential regulatory roles of osteocyte-derived IGF-I in various aspects of bone and mineral metabolism. In this review, evidence supporting a regulatory role for osteocyte-derived IGF-I in the osteogenic response to mechanical loading, the developmental bone growth, the bone response to dietary calcium depletion and repletion, and in fracture repair is discussed. A potential coordinated regulatory relationship between the effect of osteocyte-derived IGF-I on bone size and the internal organ size is also proposed.
Animals ; Bone Development ; Bone Regeneration ; Bone Remodeling ; Calcium, Dietary ; Chondrocytes ; Fibroblast Growth Factors ; Fracture Healing ; Insulin-Like Growth Factor I* ; Metabolism ; Mice ; Mice, Transgenic ; Organ Size ; Osteoblasts ; Osteocytes ; RANK Ligand ; Regeneration*

PURPOSE: The aim of the present study was to evaluate the effectiveness of using a mineralized bone cortical allograft (MBCA), with or without a resorbable collagenous membrane derived from bovine pericardium, on alveolar bone remodeling after immediate implant placement in a dog model. METHODS: Six mongrel dogs were included. The test and control sites were randomly selected. Four biradicular premolars were extracted from the mandible. In control sites, implants without an allograft or membrane were placed immediately in the fresh extraction sockets. In the test sites, an MBCA was placed to fill the gap between the bone socket wall and implant, with or without a resorbable collagenous membrane. Specimens were collected after 1 and 3 months. The amount of residual particles and new bone quality were evaluated by histomorphometry. RESULTS: Few residual graft particles were observed to be closely embedded in the new bone without any contact with the implant surface. The allograft combined with a resorbable collagen membrane limited the resorption of the buccal wall in height and width. The histological quality of the new bone was equivalent to that of the original bone. The MBCA improved the quality of new bone formation, with few residual particles observed at 3 months. CONCLUSIONS: The preliminary results of this animal study indicate a real benefit in obtaining new bone as well as in enhancing osseointegration due to the high resorbability of cortical allograft particles, in comparison to the results of xenografts or other biomaterials (mineralized or demineralized cancellous allografts) that have been presented in the literature. Furthermore, the use of an MBCA combined with a collagen membrane in extraction and immediate implant placement limited the extent of post-extraction resorption.
Allografts* ; Alveolar Bone Loss ; Animals ; Bicuspid ; Biocompatible Materials ; Bone Regeneration ; Bone Remodeling ; Collagen ; Dental Implants ; Dogs* ; Heterografts ; Mandible ; Membranes ; Miners* ; Osseointegration ; Osteogenesis ; Pericardium ; Tooth Extraction ; Transplants