• The korean journal of orthodontics
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• v.19 no.3
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• pp.137-145
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• 1989

The aim of this investigation was to study the effect of orthodontic force on the flow of gingival crevicular fluid and activities of arylsulfatase and brta-glucuronidase in crevicular fluid. The material consisted of 12 persons between the ages of 13 years and 22 years and all were categorized Class I, 4-4 extraction cases Crevicular fluids were sampled from distal crevis of each canine before treatment (phase 1), after bracketing (phase 2), after application of force (phase 3) and after run out of orthodontic force (phase 4). Crevicular fluid flow did not show any significant changes during the period of treatment. The activities of arylsulfatase increased significantly after setting of orthodontic appliance without application of force, but did not show any significant difference after application of force. The activities of beta-glucuronidase increased significantly after application of orthodontic force and decreased with force deminished. These indicated that beta-glucuronidase was good indicator of bone remodelling resulted from initial orthodontic force.

• The korean journal of orthodontics
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• v.37 no.6
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• pp.400-406
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• 2007

The purpose of this experimental study was to evaluate the effect of immediate orthodontic loading on the stability at the bone-implant interface of titanium miniscrews in a rabbit model. Methods: Forty titanium miniscrews (1.6 mm diameter, 8 mm length) were inserted in the tibiae of 10 rabbits. Twenty test group miniscrews were subjected to continuous orthodontic forces of 200g immediately after implantation for a period of 6 weeks. The remaining 20 control group miniscrews were left unloaded for the same follow-up interval. Removal torque values were recorded using a digital torque gauge. An independent t-test was performed. Results: All the miniscrews were stable, and exhibited no mobility or displacement throughout the experimental period. Histologically, miniscrews were well-integrated into bone. No statistically significant differences in removal torque data were found between the loaded test and the unloaded control groups. Conclusions: These findings suggest that titanium miniscrews can be used as anchoring units for orthodontic tooth movement immediately after insertion.

• The korean journal of orthodontics
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• v.30 no.5 s.82
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• pp.613-623
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• 2000

The purpose of this study was to amount of the frictional forces with the brackets and wires, ligation methods, dry/wet, offsets, interbracket distances, velocity and to compare them each other by different conditions. This study tested 0.018'x0.025' slot sized 8 types of orthodontic bracket systems and 0.016', 0.016'x0.022' sized stainless steel, NiTi, Cu-NiTi orthodontic wires. One cuspid bracket were positioned on the slide glass and archwire was engaged into bracket and ligated with elastomeric modules. The values of frictional forces were measured with the instron universal testing machine. The results were as follows; 1. Polycrystalline ceramic bracket had the highest mean frictional forces and followed and by ceramic reinforced plastic bracket, metal bracket, plastic bracket with metal slot, monocrystalline ceramic bracket, single bracket, self-ligating bracket, friction free bracket in descending order. The self-ligating bracket showed low frictional forces in the round wires and high frictional forces in the rectangular wires. 2. Stainless steel wires had the least frictional forces and followed by NiTi, Cu-NiTi wires in descending order. Round wires had lower frictional forces then that of rectangular wires. 3. The stainless steel ligation method had significantly greater mean frictional forces them the elastomeric module ligation method. 4. Artificial saliva statistically increased the frictional forces in stainless steel wire, NiTi wire and Cu-NiTi wire. 5. There was a statistically significant difference with offset change 6. There was no statistically significant difference with interbracket distance in stainless steel wires but a significant difference in NiTi wires as the interbracket was decreased. 7 There was no statistically significant difference with velocity change. From the above findings, self-ligating bracket, stainless steel wires and the elastomeric module ligation method might be effective than any other materials to reduce the frictional forces in the orthodontic treatment and can be correlated to clinical situations seen in orthodontic patient care.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.281-286
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• 2010

Purpose: This research provided basic data for refraction by comparing the corrected diopter of trial lens and phoropter. Methods: We compared the corrected diopter of trial lens and phoropter, and analyzed statistical significance and relations of the spherical lens corrected diopter and cylindrical lens corrected diopter according to the types (trial lens and phoropter) of subjective refractive instruments. Also we analyzed statistical significance and relations between cylindrical lens corrected diopter at the astigmatism and the types (trial lens and phoropter) of subjective refractory instruments. Results: When we measured the corrected diopter of simple myopia, the mean value for corrected diopter was S-2.74D using the trial lens and S-2.65D using the phoropter. So the corrected diopter was 0.09D smaller when measured by phoropter. The degree of astigmatism was measured C-0.81D using the trial lens and C-0.77D using the phoropter which showed that the measured value was 0.04D smaller using the phoropter. On correlation analysis between the refractive instruments (trial lens and phoropter) and the corrected diopter, there was significant (p<0.01) strong correlation between refractory machine and corrected spherical diopter (r=0.996) and the correlation between refractory machine and corrected cylindrical diopter was r=0.986 and was also significant (p<0.01). Conclusions: The use of phoropter than trial lens was more desirable when performing refraction on high myopia (simple refractive error, high astigmatism), and when using trial lens, you should consider the vertex distance and the gap between overlapped lenses before prescription.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.25-30
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• 2010

Purpose: This study was conducted to estimate the changes of corrected diopter and corrected visual acuity with the change in vertex distance. Also we aimed to provide basic data for refraction test. Methods: Using the trial lens, we measured the corrected diopter and corrected visual acuity after performing binocular balance test. We measured the changes of corrected diopter and corrected visual acuity in change of vertex distance. We analyzed statistical significance and relations between vertex distance and corrected diopter and corrected visual acuity. Results: There was no difference in corrected diopter with the change of vertex distance within -1.00D, but the corrected diopter increased with it over - 1.25D. In particular, the change of diopter was largest when the vertex distance increased 15 mm. At over 11.00D, there was large changes of diopter with the changes of vertex distance at 5 mm, 10 mm and 15 mm. On correlation analysis between the vertex distance and the corrected diopter, there was strong correlation (r=0.999 at 5 mm increase of vertex distance, r=0.982 at 10 mm increase and r=0.957 at 15 mm increase) and also there was significant (p<0.01). At the change of visual acuity in increased of vertex distance, the range of a decrease in visual acuity was large when the changes of vertex distance was largest. On correlation analysis between the vertex distance and the corrected visual acuity, there was strong correlation (r=0.969 at 5 mm increase of vertex distance, r=0.985 at 10 mm increase and r=0.994 at 15 mm increase) and also there was significant (p<0.01). Conclusions: The vertex distance was very important at the refraction test and at wearing spectacle. On correlation analysis between the vertex distance and the corrected diopter, and the corrected visual acuity, there was strong correlation and statistically significant. Therefore, the vertex distance should be kept at the refraction using trial lens, and the best fitting was made not to slipping forward, and so we suggested regular refitting of spectacle and the managing method of spectacle were educated to the spectacle wearers.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.137-142
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• 2007

The purpose of this study was to investigate sole effect of therapy of spectacles correction on the refractive amblyopia. Spectacles were prescribed to give the same effect as the occlusion therapy undercorrecting in the case of hyperopia, and effectiveness of the therapy was compared with occlusion therapy without additional prescription. The results can be summarized as follows: 1. The higher anisometropic power was the lower initial visual acuity was. 2. Anisometropic power did not influence final visual acuity. 3. The latter beginning time of therapy was the higher astigmatism was. 4. Therapy of spectacles correction on the hyperopic amblyopia was quite effective.

• The korean journal of orthodontics
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• v.25 no.1 s.48
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• pp.101-110
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• 1995

The purpose of this study was to observe the tissue response to the orthodontic force applied immediately after buccal horizontal subapical osteotomy of maxilla. Five mongrel cats weighing about 2.5 Kg were used for this experiment. The left upper canine and premolar of each cat served as a experimental side and the right ones as a control side. On the experimental side, a 100gm orthodontic force was applied between the upper canine and premolar immediately after the osteotomy. On the control side, the same orthodontic force was applied without the osteotomy. After 7days, the experimental animals were sacrificed. The results were as follows: 1. In the pressure zones of the experimental group, significant increase of osteoclasts and direct resolution along the alveolar bone surface was observed as compared with those of the control group. 2. In the pressure 2ones of the experimental group, a less extensive hyalinized zone was observed than those of the control group. 3. In the pressure zones of both group, no root resorption was found. 4. Tn the tension zones of the experimental group, new bone deposition increased along the alveolar bone surface as compared with those of the control group. In conclusion, the results suggest the possibility that early orthodontic treatment after orthognathic surgery may have some benefits if the stability of the repositioned segment at surgery is secured.

• 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.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.271-281
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• 2001

The Purpose of this study was fourfold - to evaluate the general laws of friction applied to orthodontic conditions, to compare archwire materials under these controlled conditions, to compare ligation method, and to measure the effect of the artificial saliva on friction with these materials Three wire alloys (Cobalt-chromium, Nickel-titanium, Beta-titanium) in two size wires (.016" , .016" ${\times}$.022" ) were examined respect to the bracket (.018" ${\times}$.025" standard), and two ligature material (stainless steel, elastomeric) in dry and wet conditions The results were as follows, 1. The order of frictional force against alloy materials was Co-Cr (lowest), Ni-Ti, and ${\beta}$-Ti(highest) - with the exception of elastomeric ligation under wet conditions. 2. S.S. ligation gave rise to significantly greater friction than elastomeric ligation did. 3. Testing in the presence of saliva, rather than in dry conditions, decreased the frictional force for S.S. ligation with .016" Co-Cr, Ni-Ti, ${\beta}$-Ti. but, increased the frictional force for S.S. ligation with .016" ${\times}$ .022" Co-Cr, Ni-Ti, ${\beta}$-Ti. 4. .016" ${\times}$.022 " wire generated more friction than .016" wire.

• 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.