• 대한치과교정학회지
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• 제45권3호
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• pp.121-129
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• 2015

Objective: This study aimed to assess three-dimensional changes in the temporomandibular joint positions and mandibular dimensions after correction of dental factors restricting mandibular growth in patients with Class II division 1 or division 2 malocclusion in the pubertal growth period. Methods: This prospective clinical study included 14 patients each with Class II division 1 (group I) and Class II division 2 (group II) malocclusions. The quad-helix was used for maxillary expansion, while utility arches were used for intrusion (group I) or protrusion and intrusion (group II) of the maxillary incisors. After approximately 2 months of treatment, an adequate maxillary arch width and acceptable maxillary incisor inclination were obtained. The patients were followed for an average of 6 months. Intraoral and extraoral photographs, plaster models, and cone-beam computed tomography (CBCT) images were obtained before and after treatment. Lateral cephalometric and temporomandibular joint measurements were made from the CBCT images. Results: The mandibular dimensions increased in both groups, although mandibular positional changes were also found in group II. There were no differences in the condylar position within the mandibular fossa or the condylar dimensions. The mandibular fossa depth and condylar positions were symmetrical at treatment initiation and completion. Conclusions: Class II malocclusion can be partially corrected by achieving an ideal maxillary arch form, particularly in patients with Class II division 2 malocclusion. Restrictions of the mandible in the transverse or sagittal plane do not affect the temporomandibular joint positions in these patients because of the high adaptability of this joint.

• The Journal of Advanced Prosthodontics
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• 제9권5호
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• pp.371-380
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• 2017

PURPOSE. The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions. MATERIALS AND METHODS. Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant. A 150 N vertical unilateral and bilateral load was applied at different locations and 40 N was also applied when combined with anterior load at the midline. Data for von Mises stresses in the abutment (matrix) of the attachment and the plastic insert (patrix) of the attachment were produced numerically, color-coded, and compared between the models for attachments and loading conditions. RESULTS. Regardless of the load, the greatest stress values were recorded in the overdenture attachments with implants at lateral incisor locations. In all models and load conditions, the attachment abutment (matrix) withstood a much greater stress than the insert plastic (patrix). Regardless of the model, when a unilateral load was applied, the load side Locator attachments recorded a much higher stress compared to the contralateral side. However, with load bilateral posterior alone or combined at midline load, the stress distribution was more symmetrical. The stress is distributed primarily in the occlusal and lateral surface of the insert plastic patrix and threadless area of the abutment (matrix). CONCLUSION. The overdenture model with lateral incisor level implants is the worst design in terms of biomechanical environment for the attachment components. The bilateral load in general favors a more uniform stress distribution in both attachments compared to a much greater stress registered with unilateral load in the load side attachments. Regardless of the implant positions and the occlusal load application site, the stress transferred to the insert plastic is much lower than that registered in the abutment.

• 대한치과교정학회지
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• 제47권3호
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• pp.176-185
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• 2017

Objective: To evaluate the relationship of gingival thickness (GT) and the width of keratinized gingiva (WKG) with different malocclusion groups and the level of crowding. Methods: A total of 187 periodontally healthy subjects (121 females and 66 males) who presented at the Faculty of Dentistry in $Y{\ddot{u}}z{\ddot{u}}nc{\ddot{u}}$ Yil University for orthodontic treatment were enrolled in the study. The individuals involved in the study were divided into three groups; Angle Class I malocclusion, Angle Class II malocclusion, and Angle Class III malocclusion. Each group was classified as mild, moderate, or severe according to the level of crowding. WKG was determined as the distance between the mucogingival junction and the free gingival margin. GT was determined by the transgingival probing technique. Factorial variance analysis and the Duncan multiple comparison test were employed to identify the extent to which a difference was apparent between the groups according to these parameters. Results: It was determined that teeth in the mandibular anterior region display the thin gingival biotype. WKG and GT were observed as being higher at the mandibular incisor teeth in the severe crowding group and at the mandibular canine teeth in the mild crowding group. The GT of the mandibular right central and lateral incisors was found to be thinner in the Angle Class III group. Conclusions: Within the limits of this study, the results demonstrate that, there is no significant relationship of WKG and the mean GT in the mandibular anterior region according to the Angle classification.

• 대한소아치과학회지
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• 제32권4호
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• pp.693-702
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• 2005

치아의 정확한 맹출 시기와 그 순서는 어린이의 발육 성숙도의 지표로서 소아치과 임상 및 예방 교정치료에 있어서 매우 중요하다. 이에 $2001{\sim}2003$년에 연세대학교 치과대학병원 소아치과에 내원한 어린이 중 만 5세부터 만 14세까지의 남자 654명, 여자 542명, 총 1,196명의 자료를 수집하여 영구치의 맹출 시기 및 순서에 대한 연구 결과 다음과 같은 결론을 얻었다. 1. 상악 영구치의 맹출 시기는 중절치 남 만6.81세, 여 만6.78세, 측절치 남 만8.30세, 여 만7.98세, 견치 남 만10.28세, 여 만10.04세, 제1소구치 남 만9.74세, 여 만9.90세, 제2소구치 남 만10.87세, 여 만10.41세, 제1대구치 남 만6.25세, 여 만6.54세, 제2대구치 남 만12.21세, 여 만12.03세였다. 2. 하악 영구치의 맹출 시기는 중절치 남 만6.00세, 여 만6.06세, 측절치 남 만6.99세, 여 만6.74세, 견치 남 만9.83세 여 만9.17세, 제1소구치 남 만9.92세, 여 만9.75세, 제2소구치 남 만10.66세, 여 만10.39세, 제1대구치 남 만5.99세, 여 만5.75세, 제2대구치 남 만11.92세, 여 만12.17세였다. 3. 영구치의 맹출 순서는 상악에서 제1대구치, 중절치, 측절치, 제1소구치, 견치, 제2소구치, 제2대구치의 순이었고, 하악에서 제 1대구치, 중절치, 측절치, 견치, 제 1소구치, 제2소구치, 제2대구치의 순이었다.

• 대한치과보철학회지
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• 제36권2호
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• pp.245-257
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• 1998

This study was performed to measure the changes of the mandibular movement and the masticatory muscular activities - anterior temporal and masseter muscle of both side - reflected by intentional increase of anterior guidance angie. For this study, 5 volunteers (3 males and 2 females with average age of 24.0) were selected. Each volunteer had Angle's classification I and did not have any missing tooth except third molar and any extensive restorations. Metallic guide plate was made at volunteer's working model fabricated by improved dental stone and cemented to the palatal surface of maxillary central incisor using resin cement(Panavia $21^{(R)}$) and then adjusted not to give any occlusal interferences at intercuspal position. The activity of masticatory muscles and the changes of mandibular movement were recorded by EMG and Sirognathograph in Biopak analysing system(Bioresearch Inc., Milwaukee, Wisconsin, USA). Measurement was done at before experiment, immediatley after placement, 1 week after placement, immediately after removal, and 1 week after removal. The results were as follows: 1. Moderate phonetic disturbance and mild headache were occured to 3 volunteers for 2 days after setting and 1 volunteer had positive reaction to percussion and slight midline diastema. But all of these clinical signs were diappeared 1 week after removal and the other volunteer did not have any special clinical sign. 2. In the EMG of the mandibular rest position, the mean value of anterior tempotal muscle was increased immediately after placement(p<0.01) and then decreased 1 week after placement(p<0.05) and increased 1 week after removal(p<0.05) but not recovered as before experiment. The mean value of masseter muscle was decreased during the experiment period. 3. In the EMG during mandibular protrusive movement, all muscular activity was decreased during the experiment period. Reduced activity was not recovered 1 week after removal(p<0.03). 4. During the habitual opening, anteroposterior movement of mandible was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not statistically significant(p>0.1). Vertical movement was not shown significant difference during the experiment period(p>0.1). Lateral movement was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not recovered as before experiment. The opening and closing velocity of mandible was shown minor changes but not statistically significant. 5. During the habitual opening, anteroposterior movement of mandible was decreased 1 week after placement(p<0.05) and then increased immediately after removal and recovered 1 week after removal as before experiment. Vertical movement was not shown significant changes. Lateral displacement of mandible was increased continuously and recovered 1 week after removal. Opening velocity was temporarily increased immediately after removal but recovered and closing velocity was not shown significant changes. 6. During the right side chewing, anteroposterior movement of mandible was increased immediately after removal but recovered and vertical movement was not shown statistically significant results. Lateral displacement and velocity of mandible were not shown significant results. 7. During the left side chewing, the changes of mandibular movement pattern were not shown statistically significant results.

• 대한소아치과학회지
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• 제36권2호
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• pp.253-261
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• 2009

치아 맹출은 나이, 성별, 인종, 시대에 따라 시기 및 순서의 차이가 있으나, 교과서에 인용되어 임상에서 사용되는 영구치 맹출 및 치근 형성에 대한 자료는 1933년 Logan과 Kronfeld가 발표한 것이므로 현재 한국 어린이의 영구치 맹출 경향과 차이가 있을 수 있다. 따라서 이번 연구의 목적은 한국 어린이의 영구치 맹출연령을 구하고, 이를 근거로 맹출순서를 알아보며, 이전 국내외 연구 자료와 비교하여 차이를 알아보는 것이다. 이에 1998년부터 2005년까지 연세대학교 치과대학병원 소아치과에 내원하여 구강검진을 시행한 E-초등학교의 어린이 중만 6세에서 만 12세의 2,619명 (남자 1,307명 여자 1,312명)의 자료를 수집하여 영구치의 맹출시기 및 순서에 대해 연구한 바 다음과 같은 결론을 얻었다. 1. 상악의 영구치 맹출시기는 중절치는 남자 만 6.81세, 여자 만 6.73세, 측절치는 남자 만7.78세, 여자 만7.65세, 견치는 남자 만10.48세, 여자 만9.92세, 제 1소구치는 남자 만9.76세, 여자 만9.63세, 제2소구치는 남자 만10.65세, 여자 만10.49세 제 1대구치는 남자 만6.39세, 여자 만6.26세, 제2대구치는 남자 만12.13세, 여자 만 12.03세로 나타났다. 2. 하악의 영구치 맹출시기는 중절치는 남녀 모두 정확한 시기의 측정은 불가능하였지만, 만 6.08세 이전에 맹출한다는 것을 추정할 수 있었고, 측절치는 남자 만6.78세 여자 만6.65세, 견치는 남자 만9.76세, 여자 만9.05세, 제1소구치는 남자 만9.82세, 여자 만9.59세, 제2소구치는 남자 만10.67세, 여자 만10.52세, 제1대구치는 남자 만6.22세, 여자 만 6.12세, 제2대구치는 남자 만11.58세, 여자 만 11.14세로 나타났다. 3. 맹출순서는 상악은 제1대구치, 중절치, 측절치, 제1소구치, 견치, 제2소구치, 제2대구치 순이었고, 하악은 중절치, 제1대구치 측절치, 견치, 제1소구치, 제2소구치 제2대구치 순이었다. 4. 모든 영구치에서 남자보다 여자가 빨리 맹출하였으며, 상악은 약 0.19세, 하악은 약 0.29세 먼저 맹출하였다. 5. 남녀 모두 상악은 측절치와 제1소구치 사이, 하악은 측절치와 견치 사이에 휴지기가 있었고. 남자의 휴지기는 상악 1.98년, 하악 2.98년, 여자는 상악 1.98년, 하악 2.40년이었다.

• 대한치과교정학회지
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• 제31권4호
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• pp.439-445
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• 2001

본 연구의 목적은 기능성 및 골격성 전치부 반대교합 환자에 대한 형태학적 차이점을 비교하는 것이다. 전치부의 기능성 반대교합을 보이는 28증례와 골격성 반대교합을 보이는 31증례를 각각 실험군과 대조군으로 삼았다. 실험군과 대조군의 평균연령은 $9.6{\pm}1.8$세와$9.9{\pm}1.9$세이었다. 측모두부방사선 사진을 촬영하였으며 두 군간의 형태학적 차이를 비교하기 위해 49개 항목에 대한 계측 및 통계학적인 분석을 시행하였다. 계측항목 중 cranial deflection, maxillary depth, ANB, convexity, NPo-AB, APDI, Mx 1-SN, Mx 1-NA angle, Mx 1-NA, Md 1-NB angle and Md 1-NB에서 통계학적인 유의차가 나타났다. 실험군에서는 Class III로의 성장 가능성, 상악골의 전방위치, 상하악골간의 전후방적 부조화 감소, 상악 중절치의 후퇴, 직립 및 하악 중절치의 전돌, 순측경사를 보였다.

• 대한치과교정학회지
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• 제50권2호
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• pp.120-128
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• 2020

Objective: The aims of the present study were to evaluate the changes in the maximum lip-closing force (MLF) after orthodontic treatment with or without premolar extractions and verify the correlation of these changes with dentoskeletal changes. Methods: In total, 17 women who underwent nonextraction orthodontic treatment and 15 women who underwent orthodontic treatment with extraction of all four first premolars were included in this retrospective study. For all patients, lateral cephalograms and dental models were measured before (T0) and after (T1) treatment. In addition, MLF was measured at both time points using the Lip De Cum LDC-110R^® device. Statistical analyses were performed to evaluate changes in clinical variables and MLF and their correlations. Results: Both groups showed similar skeletal patterns, although the extraction group showed greater proclination of the maxillary and mandibular incisors and lip protrusion compared to the nonextraction group at T0. MLF at T0 was comparable between the two groups. The reduction in the arch width and depth and incisor retroclination from T0 to T1 were more pronounced in the extraction group than in the nonextraction group. MLF in the extraction group significantly increased during the treatment period, and this increase was significantly greater than that in the nonextraction group. The increase in MLF was found to be correlated with the increase in the interincisal angle and decrease in the intermolar width, arch depth, and incisor-mandibular plane angle. Conclusions: This study suggests that MLF increases to a greater extent during extraction orthodontic treatment than during nonextraction orthodontic treatment.

• 대한치과교정학회지
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• 제39권2호
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• pp.112-119
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• 2009

본 연구는 다변량 기법을 도입하여 치아 크기의 다양성을 고려하면서 정확성이 높은 혼합치 열기 분석법을 개발하기 위해 시행되었다. 견치 및 소구치 크기를 예측하는 데 이용된 변수는 상악 중절치, 상악 제1대구치, 하악 중절치, 하악 측절치 및 하악 제1대구치로서 총 5개 치아 크기 변수가 이용되었다. 우선 정상교합자 연구 표본 307명을 5개 치아 변수를 이용하여 k-means 군집 분석으로 치아 크기에 따라 나눈 후 판별식을 이용, 치아 크기가 큰 그룹과 작은 그룹으로 분류하였다. 이후 견치와 소구치 크기의 합을 예측하기 위하여 남녀별, 상하악별, 치아 크기 그룹별로 다중선형 분석을 이용하여 회귀식을 구했다. 검증 표본에는 504명의 부정교합자가 이용되었으며, 이들에 대하여 정상교합자로부터 도출된 판별식을 이용하여 2그룹으로 할당한 후 정상교합자로부터 도출된 회귀식을 이용하여 상악과 하악의 견치 및 소구치 크기 합을 예측하였다. 오차 분석 결과 정상교합자는 최대 0.71, 부정교합자 검증표본은 최대 0.82 mm의 residual standard deviation 값을 보였다. 부정교합 분류별, 치아 크기 패턴별로 예측 오차의 유의한 차이는 없었다. 1 mm 및 2 mm 이상의 예측 오차를 보인 빈도는 각각 17.3%와 1.8%였다. 본 연구 결과 도출된 혼합치열기 분석법은 기존의 연구들과 비교하여 그 정확성이 높은 것으로 고찰되었다. 다만, 임상 적용 시 복잡한 계산 과정으로 인하여 전산화 환경에서 더욱 유용할 것으로 생각된다.

• 대한치과교정학회지
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• 제9권1호
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• pp.85-98
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• 1979

This investigation was designed to compare the craniofacial and dental morphology of class III malocclusion with that of normal occlusin in children, and to determine the incidence of various class III craniofacial skeletal patterns. The material selected for this study consisted in standard lateral cephalograms of eighty two Korean children, forty one boys and forty one girls, aged 10 through 12 years, having class III malocclusion, and forty two Korean children, twenty boys and twenty two girls, with normal occlusion in the same age. Using the tracings of the standard lateral cephalograms, various angular and linear measurements were recorded, tabulated and statistically analyzed, and then the class III craniofacial skeletal morphology was divided into various patterns by the degree of SNA and SNB, which respectively were below, within or beyond the normal range of those of normal occlusion. The following characteristics of the craniofacial and dental morphology of class III malocclusion were observed. 1. The cranial base length of class III malocclusion was smaller than that of normal occlusion, and the small saddle angle was a characteristic figure of class III malocclucion. 2. Maxillary length of class III malocclusion was smaller than that of normal occlusion, and point A was retropositioned relative to cranial base but not PNS in class III malocclusion. Maxillary base inclination was not significantly different between the two, but occlusal plane to palatal plane was small in class III malocciusion. 3. The mandibular body length shown no difference between the two, but the mandibular body positioned anteriorly relative to cranial base in class III malocclusion. Ramus height, gonial angle, and mandibular effective length were large in class III malocclusion. Mandibular plane angle and joint angle had no difference between the two, and occlusal plane to mandibular plane angle was large in class III malocclusion. 4. Maxillary incisor inclination was not significantly different between class III malocclusion and normal occlusion, but mandibular incisors positioned and inclined lingually and consequently interincisal angle was large in class III malocclusion. 5. Class III malocclusion was divided into six categories of craniofacial skeletal pattern. The most common class III pattern was found to be one in which the maxilla was within the normal range of prognathism while the mandible extended beyond this range. The pattern in which the maxilla was below the normal range of prognathism while the mandible was within this range was approximately one fifth of the class III sample.