• 대한치과교정학회지
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• 제50권3호
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• pp.216-226
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• 2020

Root resorption can be caused by several factors, including contact with the cortical bone. Here we report a case involving a 21-year-old female with Angle Class II, division 1 malocclusion who exhibited significant root resorption in the maxillary right central incisor after orthodontic treatment. The patient presented with significant left-sided deviation of the maxillary incisors due to lingual dislocation of the left lateral incisor and a Class II molar relationship. Cephalometric analysis demonstrated a Class I skeletal relationship (A point-nasion-B point, 2.5°) and proclined maxillary anterior teeth (upper incisor to sella-nasion plane angle, 113.4°). The primary treatment objectives were the achievement of stable occlusion with midline agreement between the maxillary and mandibular dentitions and appropriate maxillary anterior tooth axes and molar relationship. A panoramic radiograph obtained after active treatment showed significant root resorption in the maxillary right central incisor; therefore, we performed cone-beam computed tomography, which confirmed root resorption along the cortical bone around the incisive canal. The findings from this case, where different degrees of root resorption were observed despite comparable degrees of orthodontic movement in the bilateral maxillary central incisors, suggest that the incisive canal could be an inducing factor for root resorption. However, further investigation is necessary to confirm this assumption.

• Journal of Korean Dental Science
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• 제16권1호
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• pp.23-34
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• 2023

Purpose: This study aims to investigate the force delivery profile of thermoformed aligners (TFA) compared with direct-printed aligners (DPA) and to explore the effect of different activation amounts on forces and moments of respective groups. A secondary objective is to observe the amount of stress relaxation that occurs over the 7~14 days when aligners are maintained in a simulated intraoral environment. Materials and Methods: An in vitro setup was created to quantify forces and moments. It consisted of a three dimensional-printed base plate and segmented maxillary teeth, placed in a semi-enclosed chamber to maintain a temperature of 37℃. Ninety clear aligners were divided into nine groups of ten aligners each based on material types (Zendura, ATMOS, TC-85) and activation amounts. Aligners were created with 0.00, 0.25- and 0.50-mm activations for lingual bodily movement of the upper left central incisor and kept on models in the "stressed" position in a 37℃ water bath. Three force components acting on the upper left lateral incisor, upper left central incisor, and upper right central incisor were measured for each time point, beginning from the initial baseline measurement, 8 hours, 16 hours, 24 hours, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, and lastly, 14 days. Result: TC-85 aligners in every activation group showed less force on teeth than Zendura and ATMOS. Significant force levels from 0.0 mm activation were present and stayed consistent over the course of 14 days. Comparisons made for baseline measurements to 7-days and 14-days showed statistically significant change from the baseline force level. Conclusion: TC-85 aligners demonstrated lower, more consistent forces with fewer side effects. Aligners can generate forces even when no activation is programmed. No major decreases in force levels over time were observed; the intra-oral clinical simulated environment and length of observation time could contribute to this.

• 대한소아치과학회지
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• 제31권3호
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• pp.406-411
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• 2004

영구 상악 절치의 매복은 매복이 흔한 제3대구치와 상악 견치에 비해서 드물지만 상악 중절치 미맹출을 주소로 내원한 학동기 아동에서 종종 관찰된다. 매복을 유발시키는 원인에 대해서는 많은 논란이 있으나 주 요인으로는 유치의 외상과 유치의 치근단 감염이 보고되고 있다. 특히 유치의 치근단 감염에 의한 매복설이 유력한데 병소의 압력에 의한 계승영구치의 회전, 변위등의 위치변화가 일어날 수 있다고 보고되고 있다. 매복치는 무엇보다도 조기에 발견하여 치료하는 것이 이로 인해 발생되는 부정교합이나 그 밖의 부작용을 예방할 수 있다. 일단 매복이 진단되면 방사선 검사를 통하여 위치 확인을 정확히 하는 것이 중요하며 치료에 앞서 전반적인 공간분석과 치료계획을 세워야 한다. 치료로는 교정적 견인, 또는 자가이식등이 있으며, 역위 매복된 경우가 아니라면 공간 확보만으로도 50%의 자발적 맹출을 보고하고 있다. 본 증례는 유치의 치근단 감염에 의해 역위 매복된 것으로 보이는 상악 중절치를 교정력을 이용해 정상적인 맹출로 바로 잡아준 결과 4-5개월만에 자발적으로 맹출하였기에 이에 보고하는 바이다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권5호
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• pp.326-331
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• 2012

Purpose: Length measurement from maxillary anterior teeth root tip to nasal floor is incorrect in panoramic radiography. Comparison of cone beam computed tomography (CBCT) and panoramic radiography should be helpful in determining the vertical length. Methods: Sixty nine patients were taken CBCT and panoramic radiography of the maxillary anterior. First measurement is length of parallel lines from the central incisor and lateral incisor root tip to nasal floor on CBCT. Second measurement is length of perpendicular lines from the central incisor and lateral incisor root tip to nasal floor on CBCT. Third measurement is length from the central incisor and lateral incisor root tip to nasal floor on panoramic radiographys. Results: In the first measurement of the maxillary central incisors, an average of $11.36{\pm}2.49$ mm in males and $10.49{\pm}2.17$ mm in females. In the second measurement of the maxillary central incisors, $10.41{\pm}2.42$ mm in males and $9.18{\pm}2.08$ mm in females. In the third measurement of the maxillary central incisors, $10.71{\pm}2.20$ mm in males and $9.27{\pm}2.10$ mm in females. In the first measurement of the maxillary lateral incisors, an average of $13.40{\pm}2.04$ mm in males and $11.96{\pm}2.20$ mm in females. In the second measurement of the maxillary lateral incisors, $11.25{\pm}1.82$ mm in males and $10.06{\pm}1.68$ mm in females. In the third measurement of the maxillary lateral incisors, $11.47{\pm}2.01$ mm in males and $10.13{\pm}1.70$ mm in females. Conclusion: The vertical length from root tip to nasal floor was longer in male than female (P>0.05). First measurement was longer than third measurement (P<0.05). This is the actual placement of the implant site measured on the vertical length than the length of the panorama means that there are a few more free. The first measurement was longer than 114% over the third measurement.

• 대한소아치과학회지
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• 제28권3호
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• pp.383-390
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• 2001

상악중절치의 매복은 임상적으로 흔히 볼 수 있다. 대부분의 경우 중절치는 협측에 매복되어 있다. 이러한 협측매복은 치료가 무척 어렵다. 협측매복시 치은퇴축과 부착치은의 상실,치주낭이 발견된다. 따라서 성공적인 치료를 위해서는 외과적 술식을 통해서 부착치은의 소실을 최소화해야 할 것이다. 매복치의 위치와 부착치은의 양에 따라 수술방법으로 간단한 치은절제술(gingivectomy)외에도 필요하면 근단변위판막술(apically positioned flap), 측방변위판막술(laterally positioned flap), 유리치은 이식술(free gingival graft) 등과 같은 여러 판막술과 치아의 생리적인 맹출기전을 복제한 폐쇄 맹출법 (closed eruption technique)을 고려 할 수 있다. 하지만 치은절제술은 근단변위판막술에 비하여 부착치은의 양이 적어 많은 양의 부착치은 이 필요한 경우에는 근단변위판막술이 적응증이며 매복치아가 nasal spine근처에 있을 때는 폐쇄 맹출법을 선택해야 할 것이다. 본 증례에서 두 증례에서는 근단변위 판막술을 한 증례에서는 폐쇄 맹출법을 사용한 바 다음과 같은 결론을 얻었다. 폐쇄 맹출법이 더 심미적이었으나 부착치은의 양은 작았다. 이에 상악 중절치의 매복의 경우에서 올바른 임상적, 방사선학적인 검사를 통해 적응증에 맞는 외과적 수술로써 외과적 견인후 합병증을 최소화할 수 있었다.

• Imaging Science in Dentistry
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• 제41권1호
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• pp.17-21
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• 2011

Purpose : The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. Materials and Methods : This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. Results : Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. Conclusion : These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

• 대한소아치과학회지
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• 제5권1호
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• pp.27-32
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• 1978

To corroborate that the width of attached gingiva should be changed according to ages, and what relationships between the changes and the results of Glickman's clinical tension test would be, The author measured the width of attached gingiva of 85 Korean children in male, 94 Korean children in female from 8 to 11 ages and performed clinical tension test. The results were as followings; 1) At midline region of each evaluated teeth, Width of attached gingiva was the narrowest at midline region of deciduous canine, and nearly same at midline region of central incisor and lateral incisor. 2) At interproximal region of each evaluated teeth, Width of attached gingiva between left and right central incisors was the narrowest, that of between deciduous canine and lateral incisor, and between lateral incisor and cental incisor were the widest at maxilla and All were nearly same at mandible. 3) In general, width of attached gingiva of interproximal region was wider than that of midline region. 4) In this study, width of attached gingiva tended to be increasing according to ages both at maxilla and at mandible. 5) Compared maxilla with mandible, Width of attached gingiva of maxilla was wider than that of mandible. 6) The results of tension test were it that Over-all incidence was the highest in 8 year old children who had the narrowest width of attached gingiva at frenum attached region and tended to be decreasing according to ages from 8 to 11 years.

• 대한치과교정학회지
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• 제16권2호
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• pp.123-133
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• 1986

The purpose of this study was to collect the information of the straight-wire appliance and to determine the amount of second-order bends in clinical orthodontics. The author analysed the study model of 50 individuals with normal occlusion and results were obtained as follows. 1. The crown angulation was 4 degree in upper central incisor, 7 degree in upper lateral incisor, and 0 degree in lower central incisor and lateral incisor. 2. The crown angulation was 8 degree in upper cuspid and 2 degree in lower cuspid. 3. The crown angulations were 4 degree in upper first bicuspid, upper second bicuspid and lower second bicuspid and 1 degree in lower first bicuspid. 4. The crown angulation was 3 degree in upper first molar, 0 degree in upper second molar, 5 degree in lower first molar and 8 degree in lower second molar. 5. The crown angulations in lower arch were progressively increased from first premolar to second molar. 6. In upper arch, as the crown angulation of one tooth was increased, those of adjacent teeth were increased, too. 7. In the case of lower arch, the crown angulation of cuspid was increased as that of lateral incisor was increased, the crown angulation of second premolar was increased as that of first premolar was increased, and similarity the crown angulation of second molar was increased as that of first molar was increased.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.77-90
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• 2024

PURPOSE. The study aims to investigate the influence of the ferrule effect and types of posts on the stress distribution in three morphological types of the maxillary central incisor. MATERIALS AND METHODS. Nine models were created for 3 maxillary central incisor morphology types: "Fat" type - crown 12.5 mm, root 13 mm, and buccolingual cervical diameter 7.5 mm, "Medium" type - crown 11 mm, root 14 mm, and buccolingual cervical diameter 6.5 mm, and "Slim" type - crown 9.5 mm, root 15 mm, and buccolingual cervical diameter 5.5 mm. Each model received an anatomical castable post-and-core or glass-fiber post with resin composite core and three ferrule heights (nonexistent, 1 mm, and 2 mm). Then, a load of 14 N was applied at the cingulum with a 45° slope to the long axis of the tooth. The Maximum Principal Stress and the Minimum Principal Stress were calculated in the root dentin, crown, and core. RESULTS. Higher tensile and compression stress values were observed in root dentin using the metallic post compared to the fiber post, being higher in the slim type maxillary central incisor than in the medium and fat types. Concerning the three anatomical types of maxillary central incisors, the slim type without ferrule height in mm presented the highest tensile stress in the dentin, for both types of metal and fiber posts. CONCLUSION. Post system and tooth morphology were able to modify the biomechanical response of restored endodontically-treated incisors, showing the importance of personalized dental treatment for each case.

• Journal of Oral Medicine and Pain
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• 제7권1호
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• pp.59-65
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• 1982

For the purpose of estimation of age based on changes in the human root dentin transparency, 173 extracted teeth in each part of upper & lower Lt. & Rt. central, lateral incisors to Lt. & Rt. 2nd premolars were evaluated and analized in terms of root dentin transparency. The results are as follows : 1. It was reconfirmed that there exisits coparatively close correlatonship between age and the root dentin transparency. 2. It was proved that the correlation between the changes in the length and the area of the root dentin transparecy in accordance with the ages of each tooth was highest at the upper central incisor, and next at the low central incisor and the upper second premoloar respectively. 3. In the analysis of the age of the transparency, the error was less in the measurement of the area than in the measurement of the length in regard to the estimation of age. 4. The results from the test of the upper central incisor were boiled down to the following linear equation about the correlation among the area and the length of the transparency, and the age: Y=6.94X+14.7(r=0.59) (Y:estimated age, X:length mm) Y=138.47X+12.31(r=0.72) (Y:estimeted age, $X:area\textrm{cm}^2$)