• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.386-391
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• 2010

Introduction: Bone resorption is a unique function of osteoclasts. Osteoclasts are a specialized macrophage polykaryon whose differentiation is regulated principally by macrophage colony-stimulating factors, receptor activator of nuclear factor ${\kappa}B$ ligand (RANK) ligand, osteoprotegerin (OPG), and interleukins (IL). Reflecting the integrin-mediated signals, osteoclasts develop a specialized cytoskeleton that allows it to establish an isolated micro-environment between itself and the bone, wherein matrix degradation occurs by a process involving proton transport. The levels of IL-1, IL-6, OPG, and prostaglandin $E_2$ ($PGE_2$) expression were evaluated to study the correlations between dental implant teeth and the adjacent teeth. Materials and Methods: The exudate of the gingival crevice acquired from dental implants, adjacent teeth, opposite teeth and contralateral teeth of 24 patients. Results: 1. The levels of IL-1, IL-6, OPG and $PGE_2$ expression in dental implant teeth were higher than those of the contralateral teeth. 2. IL-1 revealed a higher expression level in the adjacent teeth than in dental implant teeth. 3. The dental implant teeth and adjacent teeth did not show a remarkable difference in the level of IL-1 expression. 4. All the other cytokines were strongly expressed in the dental implant compared to the adjacent teeth. Conclusion: These results suggest that there might be close correlation between dental implant teeth and adjacent teeth in terms of the expressions of cytokines that affect the development and regulation of osteoclasts.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.29-37
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• 2011

Purpose: In cases when implant supported overdenture is made by using standard size implant, additional procedure such as bone surgery and bone grafting can be required. And it gives burden to doctor and patient in terms of cost. Therefore, it is necessary to find the implant therapy for the edentulous patients in making denture with accordable cost and simple procedure. Materials and methods: Edentulous patients with upper and lower dentures participated in this study. Before the operation, survey about patient's satisfaction to the existing dentures was carried out. Surgical procedures included four small diameter implants installation anterior area and immediate loading. One and three month after the procedure, the same survey about patient's satisfaction was carried out, and radiography was taken. Results: We are doing research to the nine patients. Survival rate is 97.2 percent. The comparison of patient's satisfaction before and after surgery is performed based on oral health impact profile 49. We analyze mainly with masticatory discomfort, retention, aesthetics, social problem, psychological discomfort problems. As a result, satisfaction level is increased at all factors. Retention is the most increased satisfactory factor followed by mastication difficulty, pronunciation, psychological discomfort, social discomfort, aesthetics in order. Marginal bone loss is 0.21 mm at 12 weeks after implant placement. Conclusion: This research reveals that the denture supported by mini dental implant increases patient's satisfaction. This study will be continued with more patients for a long time and we are scheduled for taking additional radiography to check whether peri-implant bone resorption occurs or not.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.223-234
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• 1992

The purpose of this study was to investigate the changes of periodontal tissues in the irradiated mandibular bone in rats which were fed normal diet and low calcium diet In order to carry out this experiment, 64 seven-week old Sprague-Dawley strain rats weighing about 150gms were selected and equally divided into one experimental group of 32 rats and one control group with the remainder. The experimental group and the control group were then subdivided into two groups when the rats reached the age of 10 weeks, 16 rats were allotted for each subdivided group was composed of 16 rats and exposed to irradiation. The two groups were irradiated a single dose of 20Gy on the only jaw area and irradiated with a cobalt-60 teletherapy unit The rats in the control and experimental groups were serially dissected by fours on the 3rd, the 7th, the 14th, and the 21st day after irradiation. After each dissection, both sides of the dead rat mandibular bodies were removed and fixed with 10% neutral formalin. The specimens sectioned and observed in histopathological. histochemical. and immunocellular chemical methods. The obtained results were as follows: 1. In the mandibles of rats with low calcium diet the increased number of fibroblasts of periodontal ligaments. many small capillaries and irregular arrangement of loose collagen fibers were detected and the partial resorption of dentin and cementum could be found by the microscopic studies. 2. In the group of irradiated rats, degenerated periodontal tissues led to the condition of irregular arrangement of collagen fibers and the decreased number of fibroblasts. But this condition was somewhat restored after 21 days of experiment. 3. Periodontal tissues of the irradiated rat group with low calcium diet were destroyed earlier than those of the irradiated rat group with normal diet. Soon this condition was restored and then high cellularity and dense collagen fibers were observed. 4. Many periodontal cells bearing tumor necrosis factor could be clearly observed in the nonirradiated group of rats with normal diet, whereas could not be observed on the 7th day and reappeared on 14th day in the irradiated group of rats with normal diet. A few of them could be observed in the group of rats with low calcium diet, but they could be clearly observed in the both groups after 21 days of experiment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.1
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• pp.64-70
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• 2010

Soybean is of particular interest as a food supplement of isoflavones for inhibiting bone resorption in postmenopausal woman. These beneficial effects of isoflavones are caused by functioning as partial agonists or antagonists of estrogen, of which anti-resorptive effect is mediated indirectly through paracrine factors produced by osteoblasts that act on osteoclasts. In this study, the indirect effect of soybean on osteoclastic differentiation of RAW264.7 cells were investigated. The conditioned medium was collected from MC3T3-E1 osbeoblasts treated with 0.001 mg/mL~0.1 mg/mL soybean extracts for 6 days, mixed in 1:1 ratio with osteoclast medium, and then added into RAW264.7 cells with receptor activator of nuclear factor kappa B ligand (RANKL), a differentiation inducer for 3 days. Of paracrine factors in the conditioned medium, the protein expression of osteoprotegerin (OPG) with soybean extract was specifically higher in a dose dependent manner than with $10^{-9}$ M~$10^{-6}$ M of estrogen, genistein or daidzein standards. In RAW264.7 cells, the conditioned medium with soybean inhibited RANKL induced osteoclastic differentiation as total number of multinucleated tartrateresistant alkaline phosphatase (TRAP)-positive osteoclasts and protein expression of MMP-9 were significantly decreased. Coupled with the low expression of estrogen receptor $\alpha$ and $\beta$ proteins in RANKL treated RAW264.7 cells, we demonstrate that the conditioned medium of soybean treated osteoblasts inhibits RANKL induced differentiation of osteoclasts with the selective expression of OPG in osteoblasts.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.37-44
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• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.

• The korean journal of orthodontics
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• v.33 no.3 s.98
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• pp.199-210
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• 2003

Tooth movement is the result of bone metabolism in the periodontium, where various cytokines take important roles. Interleukin-6(II-6) and nitrous oxide (NO) were reported to be secreted from osteoblasts in the process of bone resorption. The mechanism of the process has not been clearly understood, but the activation of mitogen-activated protein kinase (MAPK) was known to be an important process in the release of the inflammatory cytotines in macrophages. In this regard, to prove the role of MAPK in the release of IL-6 and NO in MC3T3E-1 osteoblasts, Northern blot analysis, Western blot analysis and immune complex kinase assay were used. As a result, the treatment of MC3T3E-1 osteoblast cultures with combined $interferon-\gamma(IFN-\gamma)$, lipopolysaccharide (LPS) and tumor necrosis $factor-\alpha(TNF-\alpha)$ induces expressions of inducible nitric oxide synthase (iNOS) and IL-6, resulting in sustained releases of large amounts of NO and IL-6. However, $IFN-\gamma,\;LPS,\;and\;TNF-\alpha$ individually induce a non-detectable or small amount of NO and IL-6 in MC3T3E-1 osteoblasts. The role of MAPK activation in the early intracellular signal transduction involved in iNOS and IL-6 transcription in the combined agents-stimulated osteoblasts has been investigated. The p38 MAPK pathway is specifically involved in the combined agents-induced NO and IL-6 release, since NO and IL-6 release in the presence of a specific inhibitor of p38 MAPK, 4-(4-fluorophenyl)-2-(4-metylsulfinylphenyl)-5-(4-metylsulfinylphenyl)-5-(4-pyridyl)imidazole) (SB203580), were significantly diminished. In contrast, PD98059, a specific inhibitor of MEK1, had no effect on NO and IL-6 release. Northern blot analysis showed that the p3a MAPK pathway controlled the iNOS and IL-6 transcription level. These data suggest that p38 MAPK play an important role in the secretion of NO and IL-6 in $LPS/IFN{\gamma}-or\;TNF-\gamma-treated\;MC3T3E-1$ osteoblasts.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.206-216
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• 2000

Predictional study for lateral change between pre- and post-orthognathic surgery has been emphasized mainly on anterior area of lateral profile; upper lip, lower lip and chin et al. So interest for lateral profile change has been less in posterior area of lateral profile and literature analyzing gonial angle change is rare. The purpose of this study is to make prediction for gonial angle change possible and to offer somewhat treatment guidance for gonial angle to be improved by investigating overall gonial angle change between pre- and post-orthognathic surgery and inquiring into factors influencing on pattern of genial angle change. For this study 35 patients were selected retrospectively. Lateral cephalometric radiographs were taken in just pre-op time, pod 1 day, pod 1 year. They were analyzed and genial angles were measured. The results were as follows : 1. Gonial angle at pod 1 day was decreased about $9.3^{\circ}$ than pre-op and gonial angle at pod 1 year was increased about $4.0^{\circ}$ than pod 1 day. So genial angle at pod 1 year was decreased about $5.3^{\circ}$ than pre-op genial angle(p<0.01). 2. Mean pre-op gonial angle was $129.4^{\circ}$, showing significantly high value than normal and mean gonial angle at pod 1 year was $124.1^{\circ}$, showing value near to normal. 3. Mean gonial angle change between pre-op and pod 1 year was decreased about $5.4^{\circ}$ in female and $5.3^{\circ}$ in male. There was no statistically significant difference between male and female(p>0.05). 4. Principal factor influencing on decreased gonial angle in gonial angle change between pre-op and pod 1 year was amount of mandibular setback. 5. Principal factor influencing on increased gonial angle in gonial angle change between pod 1 day and pod 1 year was % horizontal relapse, and it was thought that resorption and bone remodelling on posterior area in mandibular distal segment also were related to increased gonial angle. 6. It is thought that sagittal split ramus osteotomy in mandibular prognathic patients with high value of gonial angle is effective to improvement of gonial angle, and In patients who have normal range of gonial angle and are required with excessive mandibular setback, short lingual cut method, additional resection of posterior margin of distal segment, Obwegeser II method will be considerd. 7. More prudent operation and careful post-op management will be responsible for maintenance of postoperative stable gonial angle.