• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.605-611
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• 1995

The purpose of this study was to evaluate effects of time on shear bond strengths of a light-cured glass ionomer cement and chemically cured resin cement to enamel, and to observe the failure patterns of bracket bondings. Shear bond strength of a light-cured glass ionomer cement were compared with that of a resin cement. Metal brackets were bonded on the extracted human bicuspids. Specimens were subjected to a shear load(in an Instron machine) after storage at room temperature for 5 and 15 minutes; after storage in distilled water at $37^{\circ}C$ for 1 or 35 days. The deboned specimens were measured In respect of adhesive remnant index. The data were evaluated and tested by ANOVA, Duncan's multiple range test, and t-test, and those results were as follows. 1. The shear bond strength of light-cured glass ionomer cement is higher than that of resin cement at 5 and 15 minutes. 2. The shear bond strengths of both light-cured glass ionomer cement and resin cement increase with time. There was no significant difference in those of both 1 day group and 35 day group 3. Light-cured glass ionomer cement is suitable as orthodontic bracket adhesives

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.591-600
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• 1998

The purpose of this study was to investigate the root resolution and repair pattern of human teeth according to the force magnitude, direction and duration during the initial leveling and alignment phase. 40gms to 500gms of force applied to the 37 experimental teeth with duration of 3 weeks to 7 months. Then, the experimental teeth were extracted. 13 control teeth were extracted without treatment. The results are as follows: 1. $59.5\%$ of 37 teeth exhibited root resorption. The initial resorption site was visible at the apex within 3 weeks with 100 gms samples, and the initial repair site was visible at the apex within 3 months with 400 gms samples. 2. Number of resorbed teeth increased with the duration of the force. 3. The depth of the resorption increased with the magnitude of the force. 4. The areas of resorbed root corresponded with the loading pattern. 5. The areas of resorbed root were highly correlated with the magnitude of the force. The result of this study suggest that root resorption could occur during the initial leveling and alignment phase, These initial injuries are all small and insignificant. It is the extensive type of apical root resolution that must be regarded as deleterious to the function and stability of the tooth moved. During the initial leveling and alignment phase lighter force of the interrupted type and short treatment period would be favorable with regard to avoidance of root resorption and repair of resorbed root surface.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.18-25
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• 2005

Traumatic bone cyst is a nonodontogenic cyst without epithelial-linig which contains fluid in it's cavity, and it is limited by bone walls with no evidence of infection. Traumatic bone cyst is asymptomatic and appears more frequently in the second decade. Gender distribution is approximately equal, although males are affected slightly often than females. Radiographically the lesion shows a well demarcated radiolucent lesion of variable size and the lesion may have scalloped margins. The adjacent teeth to traumatic bone cyst remains vital. Traumatic bone cyst is usually treated by surgical exploration and currettage of the lesion. In the first case of this case report, the patient was refered from the local dental clinic for the radiolucent area under the left mandibular first molar. From the panorama radiograph at the first visit, the radiolucent area of the left mandible showed a well defined scalloped margin and identified as traumatic bone cyst. In the second case, the patient have visited for the chief complaint of swelling and abcess of right maxillary second premolar. In the radiographic check up with panorama radiograph, the radiolucent lesion with well demarcated scalloped margin was found in the right mandible body, and identified as traumatic bone cyst. In the first case, overinstrumentation was done through the mesial root canal to irrigate the lesion. In the second case, not any treatment was done, and watched the progression of the lesion. And in both cases, after two month, the radiolucency and the size of the lesion has decreased to show healing in progress.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.49-54
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• 2005

Shell teeth, a rare dysplastic condition of dentin, was first described by Rushton in 1954. It is characterized by normal enamel, extremely thin dentin, correspondingly large pulp chambers, and shortened roots. This case report is of a male 3 years old. He is refered to the Chosun University dental hospital Pediatric Dentistry because of dental caries and dentin hypoplasia. Intra-oral examination showed attrition of all primary teeth. Radiographic examination showed that the pulps were extremely large with only a shell of surrounding hard tissue. The permanent premolars were missed congenitally. The diagnosis was shell teeth. Because of behavior problem, all dental treatment was undertaken with general anaesthesia. Extration, endodontic treatment and SS crown were performed. The patient has now been wearing the space maintainer and manages it well. The patient is seen intervals for supervision and follow-up care.

• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.269-279
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• 2004

백악질 세포의 분리 및 배양방법을 확립하고, 이를 이용하여 백악질 세포의 형질특성을 알아보고자 하였다. 교정목적으로 발거된 소구치를 이용하여, 치은섬유아세포, 치주인대 세포 및 백악질 유래세포를 분리, 배양하였다. 백악질 유래 세포 배양시에는 백악질을 절제한 후 Collagenase P를 이용하여 백악질 유래 세포 외의 다른 세포의 개제를 배제하였고, 기질을 분해하여 세포의 분리 및 배양이 용이하도록 하였다. 분리 및 배양시기의 세포의 형태를 광화현미정을 이용하여 관찰하였다. 조골세포의 특성을 가지는 SaOs-2 세포를 대조군으로 이용하여 분리 및 배양된 세포군들을 동일한 조건으로 배양하였다. 3일 및 7일째에 세포증식도를 측정하였고 7일째에 ALPase 효소 활성도를 측정하였다. 각 세포의 형질 특성을 알아보기 위해 RT-PCR을 실시하여 조골세포 분화 표식자와 연관된 osteopontin(OPN), Alkaline phosphatase(ALP), type I collagen(COL-I), Bone sialoprotein(BSP), BMP-2 및 osteocalcin(OC)의 발현을 비교 관찰하였다. 백악질 유래 세포의 분리 및 배양을 시도한 5명의 치아 중에서 3명의 치아에서 세포군을 배양해 낼 수 있었다. 배양한 백악질 유래 세포는 섬유아세포와 유사한 형태와 증식을 보였다. ALPase 효소 활성도 검사 결과 백악질 유래 세포는 SaOs-2 세포보다 낮은 활성도를 나타내었으며, 배양된 세포의 RT-PCR 결과 백악질 유래 세포군에서는 ALPase의 발현이 나타나지 않았고, 다른 조골세포 표식자의 발현도 낮게 나타났다. 이는 백악질 유래 세포가 조골세포 및 다른 대조군의 세포와는 다른 형질 특성을 가지고 있다는 것을 시사한다. 이상의 관찰결과로 사람의 백악질 유래 세포롤 백악질의 절제 및 효소처리 방법으로 효과적인 분리 및 배양이 가능하며, 이는 향후 백악질 세포의 형질 특성 및 백악질 형성의 분자적 기전을 파악하는 중요한 연구자료로 활용 될 수 있을 것으로 사료된다.

• The korean journal of orthodontics
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• v.32 no.2 s.91
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• pp.143-153
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• 2002

The bonded orthodontic retainer constructed from composite and multistrand orthodontic wire provides an esthetic and efficient system for maintained retention. This study was designed to measure shear bond strength of bonded retainers and to suggest a optimal combination of a multistrand wire and bonding method used when bonded retainer was fabricated. 160 sound maxillary and mandibular premolars were used for 80 test samples. After Uniformizing bonding area, length of wire, and thickness of composite, multistrand wire was bonded to fabricated a bonded retainer by direct or indirect bonding method. Shear bond strength and extension length of each sample were measured by a universal testing machine. The results of this study were as follows : 1. In vitro shear bond testing found 6-stranded, 0.0155 inch wires to have the largest shear bond strength and 3-stranded, 0.0195 inch wires to have the least shear bond strength. But, These difference was not statistically significant(p<0.05). 2. In vitro extension testing found 3-stranded, 0.0155 inch wires to have the largest extension length and 3-stranded, 0.0195 inch wires to have the least extension length(p<0.05). The larger diameter wire was used, the larger extension length was shown. But, the strand of wire is not related to the extension length of wire. 3. In comparison with direct bonding method, larger shear bond strength and extension length was shown in indirect bonding method(p<0.05).

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.247-261
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• 1995

The purpose of this study was to quantitate differences in the nature of the correction of Angle's Class II div 1 malocclusion dependent on the patient's age at the time of treatment. The sample consisted of 27 female patients in the adolescent group with a mean initial records age of 11.8 years and 25 female patients in the adult group with a mean starting age of 21.1 yrs. Lateral cephalometric head films were taken before and after orthodontic treatment with four bicuspid extraction. The results were obtained as follows. 1. None of maxillary skeletal parameters exhibited a significantly different in treatment change between adolescents and adults. But, in mandibular skeletal measurements, there were significant differences between two groups. (P<0.05) 2. Measures of vertical dimension in the adults remained unchanged during treatment, reflecting the effective absence of growth. 3. The steepness of occlusal plane in the adults changed significantly.(P<0.05) In contrast, the adolescents displayed stability of the occlusal plane. 4. According to the Johnston analysis, there was a significant difference in the total molar correction between two groups.(P<0.05) 5. According to the Johnston analysis, differential mandibular growth in the adolescents contrubuted $63\%$ of the total molar correction, with orthodontic tooth movement accounting for the remaining $37\%$. In the adults, dental movement comprised $99\%$ of the correction.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.343-351
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• 1998

The purpose of this study was to investigate the pretreatment and posttreatment dentofacial characteristics of non-extraction patients with Class I malocclusion. And to compare this result with matched non-orthodontic normal occlusion and Class I premolar extraction patients. Such comparison might help identify morphologic characteristics of the non-extraction patients. Initial and final cephalometric evaluation were compared in a sample of 22 patients with Class I malocclusions treated in non-extraction manner with edgewise appliance and MEAW The mean age of the total population was 14 years 9 months and the average treatment time was 2 years 8 months. 32 landmarks were located and digitized on each cephalogram. From these landmarks, 24 linear and angular dimension were obtained. Student's t-test were used to compare the pretreatment - posttreatment results, Nonextraction - Normal groups, and nonextraction Extraction groups. Significance was predetermined at $p{\leq}0.05$. The results were as follows. 1. Before treatment, the mean value of the $ODI\;was\;69.9^{\circ},\;APDI\;was\;82.1^{\circ},\;CF\;was\;152^{\circ},\;EI\;was\;152^{\circ}$ in the non-extraction groups. 2. The skeletal pattern of the non-extraction groups were similar with non-orthodontic normal groupsr, but the non-extraction groups had larger interincisal angle. 3. Comparison between groups treated with and without extraction indicated at pretreatment, the extraction groups had more protrusive lips, smaller interincisal angle, and EI. 4. After treatment, there was no significant changes in the skeletal pattern of the non-extraction groups, but uprighting of the maxillary and mandibular first molar and decrease of the interincisal angle were seen.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.279-285
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• 2009

The purpose of this study was to evaluate histologic result of bone substituting materials on extraction sockets. We compare the histologic findings of control, $MBCP^{(R)}$, $Polybone^{(R)}$. Mandibular premolar teeth of Beagle dogs were extracted available for bone filling. All alveolar extraction sockets were thoroughly debrided with surgical curet to remove the periodontal ligament. The graft materials were filled into the extraction sockets. The animals were sacrified 90 days after implantation. Both treated and control mandibular sites were histologically evaluated with light microscopy. Histological observation at 90 days revealed that control and experimental sites were healed uneventfully without any adverse tissue reaction. Regenerated new bone formation ratio is 34.5% for control, 28.4% for $MBCP^{(R)}$, 23.8% for $Polybone^{(R)}$. From this results, it was suggested that $MBCP^{(R)}$, $Polybone^{(R)}$ are promising bone substituting materials to promote normal tissue healing and new bone formation.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.285-291
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• 2007

The purpose of this study was to evaluate the effect of collagenase and esterase on the microtensile bond $strength({\mu}TBS)$ in dentin bonding. After resin composites were bonded to occlusal dentin. ${\mu}TBS$ specimens were formed and stored in PBS, collagenase, or esterase solution After 4-week storage, ${\mu}TBS$ was determined and, the results were as follows : 1. ${\mu}TBS$ values of Single Bond 2 were lower than those of Clearfil SE Bond for all storage medium (p<0.05). 2. In Single Bond 2 group, collagenase solution lowered bond strength more than PBS and esterase solution (p>0.05). 3. In Clearfil SE Bond group, esterase solution lowered bond strength more than PBS(p>0.05). Collagenase solution lowered bond strength more than esterase solution(p>0.05) and PBS(p<0.05).