• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.535-549
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• 1999

The Purposes of this study were to investigate the initial tissue changes on the teeth and surrounding tissues under contraction and intrusive force by contraction UTA. A control and experimental dogs, 10-months in age, were studied. Contraction and intrusive force(60gm) were applied at upper four incisors by contraction UTA. Experimental dogs were sacrificed at 2 weeks and 4 weeks after force application, respectively. In this study, 2 experimental groups were designed by the duration of force applied(E1, E2). The specimens were taken around the upper first and second incisor in each groups and were prepared for the H-E and MT stain for light microscopic observation. From the results of the study, the following conclusions may be drown. : 1. In control group, the periodontal ligament width was constant from apical third to cervical third of the root and periodontal fiber arrangement was horizontal or oblique in cervical third, oblique in middle third and apical third. In alveolar bond, smooth appearance was shown with osteoblast. 2. In experimental group 1, in proportion to force was concentrated at labial middle third and apical third of root of the upper first and second incisors, root of these tooth tipped labially and intruded at a time. 3. In experimental group 2, periodontal ligament width and arrangement was similar to control and observed strong calcified response at the labial middle third of root. But, alveolar bond resorption and cementum resorption were as before seen at labial middle third and apical third of root that force was concentrated.

• 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.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.905-914
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• 1998

The goals of this study were to present presurgical naso-alveolar molding (PNAM) appliance in unilateral cleft lip and palate treatment and to evaluate the effects of PNAM appliance on alveolar molding. Samples were consisted of 4 unilateral cleft lip and palate infants (3 males and 1 female, mean age=23.2 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the greater and lesser segment was 8.27mm and average duration of alveolar molding treatment was 9.7 weeks. These patients' models were obtained at initial visit (T1) and alter successful alveolar molding (T2). Seven linear and five angular variables were measured by using photometry and digital caliper. All statistical analyses were performed by SPSS win ver. 7.5 program. Paired t-test was used to compare the mean values. 1. The posterior part of alveolar segments are the stable structures during alveolar molding treatment period in infants. 2. Forward growth of the greater segment may be hindered by the action of alveolar molding. 3. The closure of cleft gap during alveolar molding were usually due to inward and backward bending of the anterior part of the greater segment and outward bending of the whole lesser segment.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.337-347
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• 2009

Objective: The aim of this study was to evaluate the effects of vitamin E ($\alpha$-tocopherol) administration on bone formation in response to expansion of the inter-premaxillary suture, in rats, histomorphometrically. Methods: Thirty 50 - 60 day old Wistar rats were separated into five equal groups (one control and four experimental). All groups were subjected to inter-premaxilla expansion with 50-gram of force. Six control animals received saline solution (Group I) and three experimental groups were treated with a single dose of $\alpha$-tocopherol injected into the inter-premaxillary suture after one day after appliance placement (Group II: 2 mg/kg; Group III: 10 mg/kg; and Group IV: 50 mg/kg). A further group of six animals received three injections of 10 mg/kg $\alpha$-tocopherol, one each on days 3, 6, and 9 (Group V). Bone formation in the suture was evaluated by bone histomorphometry. Kruskal-Wallis rank and Mann-Whitney U tests were used for statistical evaluation at p < 0.05 level. Results: New bone area, bone perimeter, feret's diameter and newly formed bone measurements were significantly higher in the experimental groups than the control (p < 0.001). Bone architecture in $\alpha$-tocopherol administrated groups was improved, and bone formation during the expansion period was stimulated significantly, in a dose-dependent manner. Conclusions: The application of $\alpha$-tocopherol during the early stages to orthopedically expanded inter-premaxillary suture areas may stimulate bone formation and shorten the retention period, in rats.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.175-182
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• 2013

Purpose: The purpose of this study was to investigate the effect of different administration duration of alendronate on initial wound healing and new bone formation of extraction socket in rats. Materials and methods: Fifteen male Sprague-Dawley rats (body weight 130-140 g, 4 weeks old, male) were divided into control group (no alendronate administration) and experimental group (alendronate administration). Experimental group was subdivided into 1 week administrated group, 2 week administrated group, 4 week administrated group and 6 week administrated group according to duration of administration. For the experimental groups, during the designated time period (at the time of extraction, 1 week before extraction, 3 week before extraction and 5 week before extraction) till 1 week after extraction, rats were subcutaneously injected with Alendronate at the dose of 1.0 mg/Kg three times a week. Each specimen from 6 week experimental group and control group were used for microarray analysis, and other specimens were used for histological analysis. The rate of new bone formation within the extraction site and bone loss activity was analyzed using TRAP staining. Statistical analysis was performed using Kruskal Wallis test. (${\alpha}=.05$) Results: After one week from the time of extraction, the rate of new bone formation within extraction site for the control group ($16.77%{\pm}1.36%$) compared to the 4 week experimental group ($14.99%{\pm}6.26%$) was lower. However, no statistically significant difference was found. Increase in the number of inactive lacuna (empty lacuna) and decrease in the number of TRAP positive cell were identified with increased duration of administration. There was no significant difference. Conclusion: The results of this study showed as the duration of Alendronate administration increased the rate of new bone formation decreased with loss of bone activity and reduced number of osteoclast.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.9-17
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• 2014

Purpose: The purpose of this study was to compare zirconia implants with titanium implants from the view point of biomechanical stability and histologic response on osseointegration when those were placed with xenograft materials. Materials and methods: Specimens were divided into two groups; the control group was experimented with eighteen titanium implants which had anodized surface and the experimental group was experimented with eighteen sandblasted zirconia (Y-TZP) implants. At the tibias of six pigs, implants were installed into bone defect sites prepared surgically and treated with resorbable membranes and bovine bone. Two pigs were sacrificed after 1, 4 and 12 weeks respectively. Each implant site was sampled and processed for histologic and histomorphometric analysis. The stability of implants was evaluated with a $Periotest^{(R)}$. And the interfaces between bone and the implant were observed with a scanning electron microscope. Results: In stability analysis there was no significant difference between Periotest values of the control group and the experimental group. In histologic analysis with a light microscope after 4 weeks, there was new bone formation with the resorption of bovine bone and the active synthesis of osteoblasts in both groups. In bone-implant contact percentage there was significant difference between both groups (P<.05). In bone area percentage there was no significant difference between both groups. In analysis of both groups with a scanning electron microscope there was a gap between bone and a surface at 4 weeks and it was filled up with bone formed newly at 12 weeks. Conclusion: When accompanied by xenograft using membrane, bone to implant contact percentage of zirconia implants used in this experiment was significantly less than that of the titanium implants by surface treatment of anodic oxidation. So, it is considered that the improvement of zirconia implant is needed through ongoing research on surface treatment methods for its practical use.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.587-592
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• 1995

The purpose of this study was to observe the pattern of bone remodellings in the periodontal ligament of dog, in which experimental tooth movement was performed A control and 5 experimental dogs, one and half year in age, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed at 12 hours, 1, 3 ,7 and 14 days after force application, respectively. And soft X-ray films were obtained and read on the sectioned periodontal tissue around mandibular premolars. The results were as follows. 1. New bone formation began to be observed in tension side at 7-day and increased at 14-day , No difference was observed between light force group and heavy force group. 2. Bone resorption was observed as a shape of destruction of lamina dura at 3-day and increased gradually at 7-day, 14-day.

• 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.

• 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.