• Applied Microscopy
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• v.31 no.3
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• pp.287-305
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• 2001

To investigate a role of cartilage canals in osteogenesis and growth of the vertebrae, in human fetuses ranging from 50 mm to 260 mm crown rump length were studied by electron microscopy. The initial appearance of cartilage canals of the vertebral body was observed at 60 mm fetus. In 80 mm fetus, primary ossification center in the vertebral body was first noted. The vertebral body showed calcified chondrocytes surrounded by a tone of hypertrophied chondrocytes and deep canals which terminated in calcified matrix. Most hypertrophied chondrocytes in the centrum showed in various stage of degeneration in disorderly arrangement. At the blind end of deep canal, osteogenic cells, osteoblasts and chondroclasts were observed. Resorption of unmineralized cartilage septa was undertaken by perivascular cells within cartilage canals. The ruffled border of the chondroclast was restricted to resorption site of calcified cartilagenous matrix. The periosteal bone formation was followed by the appearance of primary center of the centrum at 120 mm fetus. The osteoblasts of the perichondrium started to lay down a thin membranous bony lamella on the outer surface of the osseous trabeculae of the centrum. The processes of bone formation in the vertebral bodies were found to possess morphological similarities to that occurring at secondary center of the epiphysis of a long bone. These results indicate that the connective tissue cells within the cartilage canals proliferate and differentiate into osteoblasts at the site of endochondral ossification of the vertebrae.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.431-440
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• 1998

While periodontal disease results in the extrusion of upper incisors with interdental spacing in adult patient, the intrusive movement should be executed for the rehabilitation in terms of esthetics and function. The present study was peformed to investigate the periodontal response following orthodontic intrusion of teeth with infrabony pocket. Bone defect and periodontal disease were produced adjacent to the both maxillary second lateral incisors in four adult dogs. Four weeks later, a flap operation was performed to eliminate inflammation and a reference notch was made on the root surface at the level of bottom of each defect. Two weeks after periodontal surgery, 4 weeks of intrusion and subsequent another 4 weeks of retention was executed on the right side of incisors while left incisors served as the control. Through the histologic analysis, following results were obtained. 1. Histologic section of control side showed the reduction of pocket depth after flap operation. However, the status of long junctional epithelium was observed while new connective tissue attachment occurred in a small area adjacent newly formed cementum 2. Epithelial attachment was less around the intruded incisor while new connective tissue attachment was much more compared to the control side. 3. Plenty of cells were observed in the connective tissue around the reference notch of the intruded incisor and the degree of the new cementum formation was higher in the intruded incisor than the control. The results of the present study suggested that an orthodontic intrusion of periodontally involved and extruded incisors could be carried out with a desirable periodontal response, provided that inflammation is under control.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.559-568
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• 1997

For orthodontic tooth movement, optimal orthodontic force should be maintained without periodontal breakdown and alveolar bone should be remodeled physiologically Therefore, To obtain proper occlusion through tooth movement within alveolar bone, we should know the biomechanics of teeth and supporting 4issues. The present study was performed to observe histologic changes of periodontal tissue immediately after application of orthodontic force and during the retention period in growing young adult dogs. In this study, experimental group contained between mandibular left canine and 1st molar and control group contained contralateral teeth of same animal. The .018'x.022' stainless steel closed coil spring(Dentaurum Co.) was ligated on the experimental teeth at initial 200gm-force from mandibular canine to 1st molar The animals(4 to 6 months aged young adult dogs) were sacrificed on 0, 14, 28 days after the finish of appliance activation, and then tissue samples were divided into hematoxylin-eosin(HE) staining section, ground section, alkaline phosphatase(ALP) staining section, and tartrate-resistant acid phosphatase(TRAP) staining section. Thereafter, the preparations were examined under light microscopy The following results were obtained: 1. Immediately after the finish of appliance activation, the periodontal space was increased in tension side, but decreased in pressure side compared to that of control. The hyalinized zone was also observed in the periodontium. 2. After the 14-day retention, peridontal space was decreased in tension side and slightly increased in pressure side compared to that of immediately after the finish of appliance activation. The hyalinized zone was repaired and a few osteoblasts showing slightly new bone formation were seen. Osteoblasts were scarcely observed along the alveolar bone. 3. Aftter the 28-day retention, the periodontal fibers are normally repaired. A lot of TRAP(+) osteoclasts md increased alveolar bone resorption were observed in pressure side, and AP(+) osteoblast and increased new bone formation were observed in tension side.

• Korean Journal of Veterinary Research
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• v.47 no.2
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• pp.219-228
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• 2007

Bone allograft had been increased the need because autogenous bone graft is associated with donor site morbidity and is restricted in quantity. The bone allograft implants have to prepare properly for increasing osteoinductive ability and decreasing immune responses before providing to graft. The purpose of this study was to investigate the efficacy on new bone formation in bone allografts by treatment of implants. Cortical bone allografts were transplanted to experimental defects on midshaft of diaphyseal fibulae in 15 rabbits, which were divided to 3 experimental groups according to the preparation methods-freezing, freeze-drying, defat-freezing. The grafted regions of fibulae of all groups had been radiographed biweekly for 16 weeks to observe new bone formation and union between implant and recipient bone. Bone Alkaline Phosphatase (BALP) in all groups was evaluated biweekly till the end of the experiment to determine osteoblast activities. Unions between implant and recipient bone were observed at 30% (3 of 10 cases) of freezing, 50% (5 of 10 cases) of freeze-drying and 80% (8 of 10 cases) of defat-freezing. BALP was increased over 100% from before graft at 2 weeks of graft procedures in all union cases of freezing and defat-freezing group, then gradually decreased till 16th week. In non-union cases, there is no significant variation in BALP value. Defat-freezing method for allograft implants might be more effective for osteoinductive efficacy of implants than freezing and freeze-drying method.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.350-357
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• 2007

Bone graft had been widely investigated for reconstruction of bone defects or acceleration of bone healing in orthopedics, neurosurgery and dental surgery. Autograft is the golden standard of bone graft but it is associated with donor site morbidity and is restricted in quantity. Xenograft has been researched an alternative method for autograft. The purpose of this study was to investigate the efficacy of new bone formation according to three different preparations of implants on rabbit xenograft. Cortical bone xenografts which made from bovine femoral cortical bone were treated by freezing, freeze-drying or defat-freezing implant preparations. They were transplanted into proximal diaphyseal shaft of bifibulae of 15 rabbits which were divided into three groups according to their implant preparation method. The fibulae transplantations were evaluated radiographically and examined osteoblast activity by bone alkaline phosphatase (BALP) biweekly for 16 weeks to observe new bone formation and union of the experimental defected region. New bone formation was observed in 7 cases in freeze-drying and defat-freezing group, respectively. Union of proximal and distal end of defected region, which was considered as success of bone graft, was observed in 4 cases (40%; 4 of 10 cases), respectively. In freezing group, new bone formation was observed in 6 cases but, there is no union observed. BALP value was increased over twice after two weeks of graft procedure in all union cases of freeze-drying and defat-freezing group (two of five animals, respectively) then gradually decreased to 16th week. In non-union cases, there is no significant variation in BALP value. Defat-freezing or freeze-drying preparations of implants are more efficacious in new bone formation than freezing method on rabbit xenograft. While it is difficult to propose which is superior between defat-freezing and freeze-drying, defatting of implants may enhance new bone formation in xenograft.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.109-118
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• 2011

The aims of this study were analyze the amount of stress condition when the traction force was applied to the condyle head from the chin area of mandible and amount of distortion condition when intended 0.5 mm distraction distance from surface or one point of dissected midline of mandible. For this study, 3D finite element analysis were performed. The following results were obtained : 1. When traction force of 500 g was applied to the condyle head from the chin area, condylar neck area showed the greatest amount of stress and coronoid process was the least amount of stress area. For the amount of distortion condition, infra dental area showed the greatest. 2. When 0.5 mm of intended surface distortion was applied after dissection of mid-mandible area, base anterior area showed the greatest amount of stress but the least stress area was coronoid process. For the amount of distortion, infra dental, menton area showed the greatest amount. 3. One point distortion was applied after dissection of mid-mandible area, ramus posterior area showed the greatest amount of stress and menton area were the least stress condition. For the amount of distortion, menton area showed the greatest amount of distortion condition.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.1
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• pp.135-143
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• 1996

The aim of this study was to evaluate bone promotion of bioreabsorbable guided tissue regeneration for generating new bone adjacent to osseointegrated implants in dogs. Third premolars were extracted in dgo mandibles. Cylindrical HA-coated implants were placed into extracted sockets in dogs. And test sites were protected by $GUIDOR^{(R)}$ matrix barrier. But control sites were not protected by membrances. The sites were examined clinically, radiologically, and histologically after 1, 2, and 4 months to assess bone regeneration. The results obtained were as foolows : 1. There were the good healing and the stability of $GUIDOR^{(R)}$ matrix barrier in experimental site during the healing period. 2. Complete resorption of $GUIDOR^{(R)}$ matrix barrier was clinically observed about 4 months postoperatively. 3. The woven bone changed to mature bone with a normal cortical plate and mature, resting periosteum after 4 months. 4. In experimental site, there was a significantly greater bone promtion than observed in control site. 5. $GUIDOR^{(R)}$ matrix barrier was useful for the preparation of immediate dental implants.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.391-399
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• 1997

Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment. Expansion screw($Hyrax^{\circledR}$, Dentarum Inc.) was delevered to the palate and fumed 180 degrees every morning and evening for 8 days, giving a total expansion of 7.2mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Villanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattened-inactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased after 28-day retention.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.85-95
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• 2001

The purpose of this study was to evaluate the material for fixed type retainer, allowing physiologic tooth movement. and proper remodeling or periodontal tissue during retention period. The Present study was Performed to observe the histologic changes of periodontal tissue after application of different types of fixed type retainer after orthodontic tooth movement in young adult dogs. For this study, 4 young adult dogs were used as a experimental animal and experimental group was divided into three groups : experimental group 1 contained right side maxillayy third incisors and canines, experimental group 2 contained contralateral teeth of same animals, and control group contained mandibular premolars. And each dogs were applied the 4 different types of fixed type retainer to experimental group 1. The experimental teeth were ligated on the Sentalloy closed coil $spring^{\circledR}$(Tomy Co., Japan) from maxillary third incisors and canines and applied orthodontic force at initial 200gm-forced during 1 week. All the experimental animals were sacrificed on the 3rd week after the orthodontic teeth movement and then the specimens were taken, fixed in formalin, embeded in parafin, sectioned $6-8{\mu}m$ in thickness and stained with Hematoxylin-Eosin staining, and Masson's trichrome staining method. Examined under the light microscopy The following results were observed. 1. There were observed that decreased infiltration of giant tells in pressure side and increased the new bone forming in tension side on the specimen of 6-stranded 0.0195' $Respond^{\circledR}$(G&H Co., U.S.A.) group. Periodontal ligament fibers were much compressed or elongated in 3-stranded 0.018', 0.020' $Dentaflex^{\circledR}$(Dentarum Co., Germany), and Superbond $C&B^{\circledR}$(Sun Medical Co., Japan) groups. 2. In experimental group 1, necrotic bone inside the alveolar bone of pressure side, forming of the sharpey's fiber in osteoid tissue, and remodeling of the periodontal ligament were observed in all animals. 3. In experimental group 2, it was observed that the amount of bone resorption was equal or decreased in pressure side, and increased new bone forming and significantly decreased infiltration of giant cell than the experimental group 1. By this results, it considered that 6-stranded $Respond^{\circledR}$(G&H Co., U.S.A.) wire was the most useful material allowing early periodontal tissue remodeling.

• The korean journal of orthodontics
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• v.36 no.2 s.115
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• pp.103-113
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• 2006

Most elderly women experience a decrease in their bone density due to a deficiency of calcium intake, ovariectomy, or menopause. This study evaluated the usability of the microscrew as a skeletal anchorage system in these orthodontic treatment cases, using rats as a research group. The 4 month old sprague-dawley species rats were divided into two groups, the OS (Ovariectomy Screw), and the SS (Sham operation Screw) group. In both the OS and SS groups, microscrews were implanted into the palatal bone between the upper molar teeth and two upper incisors were retracted using NETE coil spring with 75 g of force. After 3days, the again after 7 days, 7 rats in each group were sacrificed. Three days before they were sacrificed, Alizarin red S was intraperitoneally injected, and their maxillary bone, tibia and blood from their hearts were taken. The components of the extracted blood were biochemically analyzed and non-decalcified grinding resin sections for maxillary bone and tibia were made. The sections were examined with a polarization microscope, and fluorescent microscope. Smaller concentrations of Ca and P, the inorganic substances closely related to bone density, were found in the extracted blood of the OS group. Both OS and SS groups showed a possibility of bone remodeling with a high concentration of ALP after 7 days. An increase in bone density on the tension and compression sides of the microscrew and the tension side of the tooth for both OS and SS groups was confirmed with a polarization microscope. However, the bone density of the pressure side of the tooth and apical side was decreased. More deposits of Alizarin red S in the bone after 7 days rather than 3 days seen with a fluorescent microscope suggested the existence of new bone formation.