• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.1
• /
• pp.130-135
• /
• 2010

Ectopic eruption is caused by an abnormal direction of eruptive path, most common in maxillary first molar, mandibular lateral incisor, and maxillary canine, and sometimes mandibular first molar. Ectopic eruption of first molar leads to abnormal root resorption of second deciduous molar, which, if left untreated, could cause premature loss of second deciduous molar; mesial tilting and rotation of first permanent molar; lack of space for eruption of second premolar; and occlusal problems. Therefore early treatment is advised when diagnosed as ectopic eruption. Treatment of ectopic eruption in the first permanent molar involves providing proper guidance for the direction of eruption using interproximal wedging and distal tipping methods while preserving second deciduous molar. This case report shows satisfactory results of the ectopic eruption of mandibular first molars in young patients who were treated with Humphrey appliance and Halterman appliance.

• The korean journal of orthodontics
• /
• v.41 no.4
• /
• pp.237-254
• /
• 2011

Objective: The purpose of this study was to compare the displacement patterns shown by finite element analysis when the maxillary anterior segment was retracted from different orthodontic miniscrew positions and different lengths of lever arms in lingual continuous and segmented arch techniques. Methods: A three dimensional model was produced, the translation of teeth in both models was measured and individual displacement was calculated. Results: When traction was carried out from miniscrews in the palatal slope, lingual tipping of crowns and extrusion of the maxillary anterior segment were found in both continuous and segmented arches as the lever arms were made shorter. With miniscrews in the midpalatal suture area, the displacement patterns were similar to the palatal slope, but bodily movement of the upper incisors was observed in both continuous and segmented arches with the lever arm at 20 mm. When lever arms were longer, there was less extrusion of the incisors and more buccal displacement of the canines. Such displacement was shown less in the continuous arch than the segmented arch. The second premolar showed crown mesial tipping and intrusion, and the molars showed distal tipping in the continuous arch. The posterior segment was displaced three dimensionally in the segmented arch, but the amount of displacement was less than the continuous arch. Conclusions: It is recommended that lever arms of 20 mm in length be used for bodily movement of the anterior segment. Use of continuous or segmented arches affect the displacement patterns and induce differences in the amount of displacement.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.30 no.4
• /
• pp.265-277
• /
• 2014

Purpose: The purpose of this study was to investigate the differences of displacement pattern depending on type of sliding jig and application method during maxillary molar distalization with temporary anchorage devices (TADs). Materials and Methods: Maxilla with normal tooth size and arch shape was selected to create a 3-dimensional finite element model, which included the bracket, orthodontic main archwire, removable sliding jig (R-jig). The orthodontic mini-implant anchorage was set 8 mm superiorly from main archwire, buccally between the second premolar and first molar. The base experimental design was Condition 1, which was composed $0.019{\times}0.025$ inch stainless steel (SS) of wire size of R-jig, 200 gm force, un-tied state. And the other designs varied to wire size of R-jig, magnitude of force. The results are as follows. Results: As the wire size of R-jig was increased, the deformation of R-jig was decreased. However, the displacement of second molar wasn't different each other. As the force to second molar was increased, the more displacement of second molar was observed, and the more distal tipping movement, vetical displacement was observed. Conclusion: R-jig can get distal teeth movement in orthodontic treatment without side effects.

• The korean journal of orthodontics
• /
• v.28 no.2 s.67
• /
• pp.269-276
• /
• 1998

In maxillary canine retraction by means of sliding mechanics, we designed MAS(molar anchoring spring) to prevent anchorage loss and uncontrolled tipping of tooth movement and have applied it in clinical cases. The anchorage control of the maxillary first molar and type of tooth movement of the maxillary canine were studied in 31 subjects. The measurements were made on cephalograms, orthopantomograms and dental casts. The obtained results were as follows. 1. In case of the maxillary first molar, there was a little sagittal anchorage loss, but there was no vertical & transverse anchorage loss. 2. In case of the maxillary canine, there was distal tipping movement and also there was a little intrusion tendency.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.261-261
• /
• 2021

자연하천은 직선하천보다 만곡하천으로 존재하는 경우가 많다. 하천의 만곡부에서 2차류 흐름과 나선형 흐름, 원심력이 수충부와 외측제방에 작용하여 하상에 국부적인 세굴이 발생한다. 세굴이 발생하게 되면 수충부나 외측제방에 붕괴나 피해가 일어날 수 있다. 세굴의 피해를 줄이고 만곡부유로를 조정하기 위해 날개형 수제를 설치할 수 있다. 날개형 수제를 설치한 하상은 수제의 두께, 길이, 높이, 간격, 위치, 배열 등에 따라 다르게 반응한다. 본 연구에서는 만곡 개수로에 잠긴 날개형 수제를 설치할 때 만곡 외측에서 수제 열까지의 거리가 만곡부의 유심선 변화에 미치는 영향을 이동상 개수로 수리실험으로 조사하였다. 이동상 수리실험은 폭 1.16 m, 깊이 1 m, 길이 24 m인 90° 만곡 개수로에 d₅₀이 3.3mm인 잔자갈을 깔아 하상경사 1/300로 정리한 후 수제를 설치하는 순서로 이루어졌다. 수제는 폭 20mm, 길이 70mm의 직사각형 단면 목재로 제작하여 설치하였고, 실험별 이격거리는 외측 제방으로부터 8.4 cm, 14 cm, 19.6 cm로 하였다. 실험유량은 140l/s로 3시간 동안 흘린 뒤 하상측정장치를 이용하여 주요 횡단면별 하상고를 측정하였다. 측정한 데이터를 이용하여 최심하상고의 크기와 위치, 유심선의 변화 등을 분석하였다.

• The korean journal of orthodontics
• /
• v.33 no.5 s.100
• /
• pp.339-350
• /
• 2003

The purpose of this study was to investigate the micro-implant height and anterior hook height to prevent maxillary six anterior teeth from lingual tipping and extruding during space closure. We manufactured maxillary dental arch form, bracket and wire, using the computer aided three-dimensional finite element method. Bracket was $.022'{\times}.028'$ slot size and attached to tooth surface. Wire was $.019'{\times}.025'$ stainless steel and $.032'{\times}.032'$ stainless steel hook was attached to wire between lateral incisor and canine. Length of hook was 8mm and force application points were marked at intervals of In. Four micro-implants were implanted on alveolar bone between second premolar and first molar. The heights of them were 4, 6, 8, 10mm starting from wire. We analyzed initial displacement of teeth by various force application point applying force of 150gm to each micro-implant and anterior hook. The conclusions of 4his study are as the following : 1. When the micro-implant height was 4m and the anterior hook height was 5mm and below, anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, anterior teeth were tipped labially. 2. When the micro-implant height was 6mm and the anterior hook height was 6mm and below, the anterior teeth were tipped lingually. When the anterior hook height was 6m and above, the anterior teeth were tipped labially. But lingual tipping of anterior teeth decreased and labial tipping Increased when the micro-implant height was 6mm, compared with 4mm micro-implant height. 3. When the micro-implant height was 8mm and the anterior hook height was 2mm, the anterior teeth were tipped lingually. When the anterior hook height was 3mm and above, labial tipping movement of the anterior teeth increased proportionally. 4. When the micro-implant height was 10mm and the anterior hook height was 2mm and above, labial tipping of the anterior teeth increased proportionally. 5. As the anterior hook height increased, aterior teeth were tipped more labially. But extrusion occurred on canine and premolar area because of the increase of wire distortion. 6. Movement of the posterior teeth was tipped distally during maxillary six anterior teeth retraction using micro-im plant because of the friction between bracket and were Based on the results of this study, we could predict the pattern of the tooth movement according to position of micro-implant and height of anterior hook. It seems that we can find the force application point for proper tooth movement in consideration of inclination of anterior anterior teeth, periodontal condition, overjet and overbite

• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.916-920
• /
• 2007

ADCP(Acoustic Doppler Current Profiler)는 유수의 흐름을 방해하지 않으면서 물 속으로 일정 주파수의 초음파를 전송하고, 부유하는 입자들에 의해 산란되어 돌아오는 반향을 수집, 도플러효과를 이용하여 유속을 측정하는 장비이다. ADCP는 하천을 횡단하면서 순간적인 유속을 측정하므로 시간평균한 평균유속과의 차이가 발생하지만 1초에 1회 이상의 빠른 속도로 연직유속분포를 수집하면서 이를 공간적으로 평균함으로써 순간유속이 갖는 변동성을 완화시키는 특징을 갖는다. 본 연구에서는 ADCP를 활용하여 사행하천에서 수평방향 2차원 유속분포를 측정하고자 하였다. 만곡부가 교호적으로 나타나는 사행하천의 흐름구조는 매우 복잡하다. 특히 주 흐름의 수직인 단면에 나선형의 2차류가 관찰되는데, 이는 원심력과 횡방향의 수면경사 및 난류의 상호작용으로 발생된다. 주 흐름의 유속과 다른 분포를 나타낸다. 본 연구에서는 이찬주 등(2005)이 제시한 공간평균기법과 이동경로 수정을 통하여 측선별 2차원 유속분포를 측정하여 기 개발된 RAMS(서울대학교, 2007)를 적용하고 이를 검증하기 위한 자료를 확보하고자 하였다.

• The korean journal of orthodontics
• /
• v.41 no.6
• /
• pp.384-398
• /
• 2011

Objective: The purpose of this study was to analyze the stress distribution and the displacement pattern of mandibular anterior teeth under various intrusive force vectors according to the position of orthodontic miniscrews and hooks, using three-dimensional finite element analysis. Methods: A three-dimensional finite element model was constructed to simulate mandibular teeth, periodontal ligament, and alveolar bone. The displacement of individual tooth on three-dimensional planes and the von Mises stress distribution were compared when various intrusion force vectors were applied. Results: Intrusive forces applied to 4 mandibular anterior teeth largely resulted in remarkable labial tipping of the segment according to the miniscrew position. All 6 mandibular anterior teeth were labially tipped and the stress concentrated on the labiogingival area by intrusive force from miniscrews placed mesial to the canine. The distointrusive force vector led to pure intrusion and the stress was evenly distributed in the whole periodontal ligament when the hook was placed between the central and lateral incisors and the miniscrew was placed distal to the canine. Conclusions: Within the limits of this study, it can be concluded that predictable pure intrusion of the 6 anterior teeth segment may be accomplished using miniscrews placed distal to the canine and hooks located between the central and lateral incisors.

• The korean journal of orthodontics
• /
• v.31 no.3 s.86
• /
• pp.325-333
• /
• 2001

Optimal orthodontic treatment could be possible when a orthodontist can predict and control tooth movement by applying a planned force system to the dentition. The moment to force(M/F) ratio at the bracket, has been shown to be a primary determinate of the pattern of tooth movement. As various n/F ratios are applied to the bracket on the tooth crown, strain distribution in periodontium can be changed, and the center of rotation in tooth movement can be determined. It is, therefore, so important in clinicalorthodontics to know the strain distribution in a force system of a M/F ratio. The purpose of this study was to analyze the strain distribution in orthodontic force system by strain gauge attached to tooth root, and to evaluate the usage of the method. For this study, an experimental upper anterior arch model was constructed, where upper central incisors, on the root surface of which, 8 strain gauges were attached, were implanted In the photoelastic resin, as in the case of 4mm midline diastema. Three types of closing of upper midline diastema closure were compared : 1. with elastomeric chain(100g force) in no arch wire, 2. elastomeric chain in .016“ round steel wire, 3. elastomeric chain in .016”x.022“ rectangular steel wire. The results were as follows. 1. Strain distributions on labial, lingual, mesial and distal root surface of tooth were able to be evaluated with the strain gauge method, and the patterns of tooth rotation were understood by presuming the location of moment arm. 2. Extrusion and tipping movement of tooth was seen in closing in no arch wire, and intrusion and bodily movement was seen with steel arch wire inserted.

• The korean journal of orthodontics
• /
• v.29 no.4 s.75
• /
• pp.457-466
• /
• 1999

It has been reported that skeletal relapse and dental change after mandibular setback do occur not only after intermaxillary fixation(IMF) removal but also during IMF The side effects of skeletal relapse during IMF have clinical importance because they can cause many Postoperative orthodontic Problems. Generally, the Prevention of solid union between segments, compensatory tooth movement, anterior openbite, etc. have been cited as the side effects of jaw displacement. The purpose of this study was to evaluate the skeletal relapse and dental change during IMF. The material consisted of 28 patients who were treated by BSSRO(bilateral sagittal split ramus osteotomy), wire osteosynthesis, IMF for correction of mandibular prognathism. Through cephalometric analysis, the amount and direction of surgical movement, skeletal relapse and dental change during IMF were measured. The correlation between surgical movement and skeletal relapse, between skeletal relapse and dental changes were evaluated. The following conclusions were obtained; 1. Distal segment was repositioned backward and upward, proximal segment showed clockwise rotation during surgery. 2. During ]m, anterior portion of distal segment was displaced backward and posterior portion was displaced upward. Proximal segment was displaced upward with forward movement of p-Go(gonion of proximal segment). Backward surgical movement of p-GO was significantly correlated with forward displacement of p-Go. 3. Overjet and overbite were not changed during IMF. The compensatory tooth movements during IMF were characterized by retroclination of upper incisors md retroclination, extrusion of lower incisors. These compensatory tooth movements had statistically significant correlation with upward displacement of d-Go (gonion of distal segment).