• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.2
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• pp.107-111
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• 2010

Purpose: The aim of this study is to compare the stability between Mg-incorporated implant, TiUnite and Machined implant. Materials and Methods: Premolars of 3 Mini pigs (24 months) were extracted. After 2 months later, total 27 fixtures of implants (9 of each design : Machined/ TiUnite/ Mg-incorporated) were inserted into the mandible of 3 mini-pig. Implant stability was estimated by RFA in installation to 2, 4 & 6 weeks. Statistical analysis of RFA values was performed with time and between groups using repeated measure ANOVA and turkey's multiple comparison test. Results: In analyzing the mean value for the observation periods, three types of implants yielded a slight decrease in RFA mean value after 2 week, followed by increase at 4-6 weeks. Mg incorporated oxidized implants demonstrated significantly higher RFA mean values at 6 weeks comparing other groups. The difference of RFA value with time and between groups was statistically significant. Conclusion: We concluded that Mg implants may reduce failure rates of clinical implants In the early period of bone healing and Mg implants may shorten the bone healing time from surgery to functional loading.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.173-185
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• 2001

The orthodontic osseointegrated titanium implant, a kind of intraoral skeletal anchorage can be an alternative to tooth-borne anchorage, in case that the conventional tooth-borne anchorage is not available or the anchorage is critical. This study was conducted to elucidate the effect of early loading on the osseointegration of the orthodontic titanium implant and the healing process of the impaired bone at the site of implant after removing it. In two adult beagle dogs24 osseointegrated titanium implants were inserted into the alveolar bone, with 12 implants placed in each dog. In dog1, 6 out of 12 implants were loaded with 200-300gm of force immediately after placing, and the remaining 6 implants were not loaded for 4weeks. In dog2, all 12 implants had healing period of 4weeks, and then were loaded with 200-300gm of force for another 4weeks. Following an observation period of 4 and 8 weeks, the animals were sacrificed. Then the implants and the surrounding bone of dog1 and dog2 were removed, respectively. Undecalcified sections along the long axis of implant were made and the degree of osseointegration was examined under the light microscope. The results were as follows. 1. In the histologic features of tissues around implants anchored in dog1, there was no difference between immediately loaded implants and unloaded implants. Immature woven bone was ingrowing into the thread spaces from the original compacta and in direct contact with the implant surface in part. 2. The premature loading just after 4weeks healing period did not halt the progress of the osseointegration between bone and implant surface. The woven bone around the implants was maturing into the lamellar bone which resembled the structure of the original compacta at the end of 8weeks observation period. 3. Most implants with the inflammed surrounding mucosa were lost or mobile. The mobile implants were encapsulated by fibrous connective tissue which separated the implant surface from the bone. 4. The impaired bone at the site of the implant failed to anchor was showing recovery without inflammatory reaction 2weeks after removing, with the immaure woven bone lined by active osteoblasts and osteoid. Based on the results of this study, the integration of this orthodontic implant seemed to be impaired by the inflammation of the tissue surrounding the Implant rather than by early loading on implant, and increased with time lapsed after placing the implant. The use of implant described in this report can be recommended as an orthodontic anchorage unit immediately after insertion under the careful control of orthodontic force applied and plaque.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.67-75
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• 1995

The progress of periodontal disease and the wound healing process after treatment result in alveolar bone bone change. So, detection of it is very important in the diagnosis and the radiograph of periodontal disease. Various effects have been made to assess the subtle alveolar bone change and digital subtraction radiography (DSR) has been reported to be the best method in evaluating it qualitatively and quantitatively. The present study was performed to estimate the detectable alveolar bone change qualitatively with digital subtraction radiography. For the in vitro study, 10 intraoral standard radiographs were taken from porcine dry mandible which a rectangular cortical bone chip of 0.1mm to 1.0mm thickness with 0.1mm increment was attached on the buccal surface. The radiographs without and with bone plates were reviewed at the same time by 10 observers and requested to detect the presence of cortical bone plates. Digital Subtraction radiograph was reviewed subsequently by using the DSR system(digital converter-256 grey-levels,DT 2851,Data Translation Co., U.S.A;IBM 386 ; CCD camera, FOTOVIX, Tamrom Co., Japan). The detectable thickness of cortical bone plate was O.4mm on the intraoral radiograph and 0.2mm on the subtaction images. For the human study, radiographs were taken from patients by using intraoral film holding device and aluminum reference wedge before and 3 month after bone graft and 1 week after osteoplasty. The grey level change was estimated in the subtraction images and calculated to aluminum equivalent thickness. The grey level of the grafted site was higher that that of healthy controls. Average grey levels of change on healthy controls were O.48mm aluminum equivalent. However, the amount of changes in grafted sites were 1.87mm aluminum thickness equivalent and in the site of osteoplasty were -1.49mm aluminum thickness equivalent. In conclusion, digital subtraction radiography was more effective in detecting as subtle change of alveolar bone than intraoral standard radiography. With the aid of quantitative analysis of digital subtraction radiography, alveolar bone resorption of apposition can be estimated during diagnosis and treatment of periodontally diseased patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.5
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• pp.380-390
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• 2004

Bone healing plays an important role in orthognathic and craniofacial surgery. Bone tissue repair and regeneration are regulated by an array of growth and morphogenetic factors. Bone formation and remodeling require continuous generation of osteoprogenitor cells from bone marrow stromal cells, which generate and respond to a variety of growth factors with putative roles in hematopoiesis and mesenchymal differentiation. In this study, the efficacy of a single application of hepatocyte growth factor to promote bone regeneration in 5-mm experimental calvarial defects of adult male rats was assessed histologically and immunohistochemically. The result of the experimental site were compared with those of the contralateral contral side. None of the control and experimental bone defects demonstrated complete bone closure. Bone regeneration was found close th the margine and central part of the defects. At 1, 2 weeks, there were found much significant cellural mitotic activity and many inflammatory cells and osteoblasts on the experimental site than control site. At 4, 6 weeks, new bone apposition was founded in both site but, more apposition was seen at experimental site. At 8, 12 weeks, also, some differences was found that more apposition of new bone and collagen fiber was seen on experimental site. Our results have some possibility that HGF do a early positive role to repair the bone defect. More study will be needed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.4
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• pp.290-301
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• 2002

The purpose of this study was to evaluate new bone formation and healing process in rat calvarial bone defects using $BioMesh^{(R)}$. membrane and DFDB. Forty eight rats divided equally into 4 groups of 1 control group and 3 experimental groups. Standardized transosseous circular calvarial defects (8 mm in diameter) were made midparietally. In the control group, the defect was only covered with the soft tissue flap. In the experimental group 1, it was filled with DFDB only, in the experimental group 2, it was covered $BioMesh^{(R)}$. membrane only, and in the experimental group 3, it was filled DFDB and covered with membrane. At the postoperative 1, 2, 4, 8 weeks, rats were sacrificed and histologic and histomorphometric analysis were performed. These results were as follows. In histomorphometric analysis, It showed the greatest amount of new bone formation through experimental in the experimental group 3 (P<0.001). The amount of new bone formation at the central portion of the defect was greater in the experimental group 3 than experimental group 2. $BioMesh^{(R)}$. membrane began to resorb at 1 week and resorbed almost completely at 8 weeks after operation. The collapse of membrane into the defect was observed through the experimental periods in the experimental group 2. In the area of collapsed membrane, new bone formation was restricted. These results suggest that maintenance of some space for new bone to grow is required in the use of $BioMesh^{(R)}$. membrane alone in the defect. It is also thought that use of the membrane may promote new bone growth in DFDB graft.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.3
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• pp.188-195
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• 2002

The purpose of this investigation was to evaluate the relationship between the hydration time of demineralized freeze-dried bone (DFDB) and early new bone formation in rat calvarial defects filled with DFDB. Rats (n = 43) were divided into 4 experimental groups. Standard, transosseous circular defects of the calvaria were made midparietally. In experimental group 1, the defect was grafted immediately after soaking the DFDB. In experimental group 2, the defects were grafted with DFDB after soaking the DFDB for 10 minutes. In experimental groups 3 and 4, the defects were filled after soaking the DFDB for 30 and 60 minutes, respectively. Graft sites were analyzed histologically after healing periods of 1, 2, or 4 weeks. Each group showed similar bone regeneration at each time point by histological analysis. The results of this study were as follows: 1. After 1 week, a significant amount of inflammation, granulation tissue, and edema were found. A small amount of bone was seen, but the amount of bone did not differ between groups. 2. After 2 weeks, a small amount of new bone formation and DFDB resorption were observed. 3. After 4 weeks, a greater amount of new bone formation was observed. The greatest amount of bone formation occurred in experimental group 4 after 4 weeks. We conclude that the hydration time of DFDB does not affect new bone formation and that it is very important to control inflammation in bone grafting.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.499-508
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• 2004

Regeneration of Periodontium with PRP does not only improve regeneration rate and density of bone but have a possibility to estimate faster healing process for soft tissue. And also, autogenous bone and xenogenic bone graft are effective on regeneration of periodontium. The purpose of this study is to evaluate the effectiveness of autogenous bone and xenogenic bone $(BBP^{(R)})$ grafts with the PRP technique on regeneration of periodontium. 52 Generally healthy Pt. who had pocket depth 5mm at any of 6 surfaces of the teeth were in the study at Dept. of Perio. in Dankook Dental Hospital. Open Flap was treated for 18 infra-bony pockets as control group, autogenous bone with PRP was inserted for 25 infrabony pockets as first test group, and $(BBP^{(R)})$ with PRP was inserted for 22 infrabony pockets as 2nd test group. Then evaluation was made after 3 and 6 months 1. There were significant differences between average probing pocket depth and clinical attachment level of 3, 6 months and minimal and maximal attachment level after 6 months each other. 2. There were significant differences in average probing pocket depth of control group and 2nd experimental group between 1 and 6 months. For clinical attachment level and minimal and maximal proving attachment level, there was a significant difference after 6 month of surgery. 3. There was no significant difference between two test groups for average probing depth, clinical attachment level, and minimal and maximal probing attachment level. As the result, PRP with bone graft could be very effective for regeneration of periodontium and there was no difference between xenogenic bone and autogenous bone.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.3
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• pp.265-277
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• 1991

In this study, the healing changes of the implanted bone and its surrounding tissues were examined on the histopathologic basis following implantation of the freeze - dried and radiation - sterilized allogeneic bone in Rectus abdominicus of the rat. This study was performed to see the tissue recations after implantation of the freeze - dried and radiation - sterilized allogeneic bone and whether osteogenesis or osteo - induction or osteo - conduction is happened. And the results were as follows : 1. The shape of the implanted allogeneic bone of the 1, 2 - week group specimen was similar to that of normal bone in light - microscopic finding and the atrophy of cellular organells was found in trans - mission electron - microscopic finding. 2. The implanted allogeneic bone was surrounded with the dense fibroconnective tissues, and infiltration of the chronic inflammatory cells gradually became increased. 3. Hyaline degeneration was observed in the surrounding tissue at the 3, 4, 6 - week group specimen. 4. Light - microscopically the resorption of implanted bone became prominent after 4 - week group and the necrosis of allogeneic bone implant became severe with loss of cell components in lacuna. 5. Electron - microscopically, the osteoclast - like cells ere fond after, 2 - week group. It is summarized that the osteo - conduction potential of the bone is remained just after implanting the freeze - dried and radiation - sterilized allogeneic bone on Rectus abdominicus of the rat, but gradually it disappeared with the gradual increse of chronic inflammatory reaction and osteoclastic activity. So it is suggested that the antigenicity of the freeze - dried and radiation - sterilized bone is remained and it has little osteo - conductive activity when it is implanted in the muscle.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.2
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• pp.140-150
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• 2005

Maxillary sinus lifting procedure and bone grafting are used to reconstruct atrophic maxillae. These procedure are usually followed by the placement of endosseous dental implants. Different materials and techniques can be used for sinus bone grafting. Platelets are known to contain various growth factors involved in the repair of the vasculature and tissues, and it is known that the specialized platelet secretory granules, the alpha granules, contain platelet derived growth factor(PDGF), transforming growth factor-beta(TGF-beta), insuline like growth factor-I(IGF-I), epidermoid growth factor(EGF), and others. This study was to evaluate the effect of PRP on bone formation in a sinus bone grafting. Twelve rabbits were included in this randomized, blinded, prospective pilot study. In experimental group, sinus bone grafting with autobone and platelet rich plasma. In control group, sinus bone grafting with only autobone. Rabbits were sacrificed at 2nd, 4th, 8th, 12th weeks postoperatively. Clinical and radiographic tests, histological analysis were conducted to compare both sides. In clinical examination, there in no significant difference between experimental group and control group. But, in radiographic examination, a distinct incresed in the radiopaque of the PRP experimental group at 2nd and 4th weeks. The histologic examination revealed that more new bone formation and osteoblast activity were seen in experimental group at 2nd and 4th weeks. In conclusion, PRPs action in sinus bone grafting had a capacity of increased new bone formation in a early bone healing stage.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.34.1-34.8
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• 2018

Background: Radiation therapy is widely employed in the treatment of head and neck cancer. Adverse effects of therapeutic irradiation include delayed bone healing after dental extraction or impaired bone regeneration at the irradiated bony defect. Development of a reliable experimental model may be beneficial to study tissue regeneration in the irradiated field. The current study aimed to develop a relevant animal model of post-radiation cranial bone defect. Methods: A lead shielding block was designed for selective external irradiation of the mouse calvaria. Critical-size calvarial defect was created 2 weeks after the irradiation. The defect was filled with a collagen scaffold, with or without incorporation of bone morphogenetic protein 2 (BMP-2) (1 ㎍/ml). The non-irradiated mice treated with or without BMP-2-included scaffold served as control. Four weeks after the surgery, the specimens were harvested and the degree of bone formation was evaluated by histological and radiographical examinations. Results: BMP-2-treated scaffold yielded significant bone regeneration in the mice calvarial defects. However, a single fraction of external irradiation was observed to eliminate the bone regeneration capacity of the BMP-2-incorporated scaffold without influencing the survival of the animals. Conclusion: The current study established an efficient model for post-radiation cranial bone regeneration and can be applied for evaluating the robust bone formation system using various chemokines or agents in unfavorable, demanding radiation-related bone defect models.