• Title/Summary/Keyword: Anterior displacement

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Validation of three-dimensional digital model superimpositions based on palatal structures in patients with maximum anterior tooth retraction following premolar extraction

  • Liu, Jing;Koh, Kyong-Min;Choi, Sung-Hwan;Kim, Ji-Hoi;Cha, Jung-Yul
    • The korean journal of orthodontics
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    • v.52 no.4
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    • pp.258-267
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    • 2022
  • Objective: This study aimed to evaluate the superimposition accuracy of digital modes for measuring tooth movement in patients requiring anterior retraction after premolar extraction based on the proposed reference regions. Methods: Forty patients treated with bilateral maxillary first premolar extraction were divided into two groups: moderate retraction (< 7.0 mm) and maximum retraction (≥ 7.0 mm). Central incisor displacement was measured using cephalometric superimpositions and three-dimensional (3D) digital superimpositions with the 3rd or 4th ruga as the reference point. The Wilcoxon signed-rank test and linear regression analyses were performed to test the significance of the differences and relationships between the two measurement techniques. Results: In the moderate retraction group, the central incisor anteroposterior displacement values did not differ significantly between 3D digital and cephalometric superimpositions. However, in the maximum-retraction group, significant differences were observed between the anteroposterior displacement evaluated by the 3rd ruga superimposition and cephalometric methods (p < 0.05). Conclusions: This study demonstrated that 3D digital superimpositions were clinically as reliable as cephalometric superimpositions in assessing tooth movements in patients requiring moderate retraction. However, the reference point should be carefully examined in patients who require maximum retraction.

CHANGE OF JOINT SPACE ACCORDING TO SIDEWAYS DISC DISPLACEMENT OF TMJ (악관절원판의 측방변위에 따른 관절간극의 변화)

  • Kim, Joon-Bae;Lee, Doo-Hee;Kim, Hyung-Soo;Oh, Soon-Ho
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.27 no.4
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    • pp.337-343
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    • 2001
  • Objective. Disc displacement may affect the joint space narrowing between condyle head and glenoid fossa. This study was designed to evaluate the correlation between the joint space change and the directions of disc displacement. Study Design. Two hundreds temporomandibular joints MR images of TMD patients (170 joints) and asymptomatic volunteers (30 joints) were evaluated for this purpose. Anterior disc displacement was divided into 3 stages (normal, little to mild, and moderate to severe displacement) based on sagittal images. And sideways displacement was classified as 3 categories (center, medial and lateral displacement) based on coronal images, then joint spaces were measured at medial, central and lateral parts of condyle head on coronal MR images, respectively. The joint spaces of 7 groups divided according to the severity and the direction of disc displacement were compared. Results. The reduction of the joint space was affected by sideways disc displacement at the opposite side of the condyle head, except the cases accompanied with severe anteriorly and laterally displaced disc. Conclusion. The sideways disc displacement affected on the opposite side temporomandibular joint space width.

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Occlusal Change as a Sequela of Anterior Disc Displacement without Reduction of Temporomandibular Joint: Case Reports (관절원판전위와 갑작스런 교합변화가 발생한 환자의 임상증례 및 원인에 관한 보고)

  • Hur, Yun-Kyung;Jung, Jae-Kwang;Choi, Jae-Kap
    • Journal of Oral Medicine and Pain
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    • v.36 no.2
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    • pp.107-115
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    • 2011
  • We report 4 patients who developed change of occlusion which seemed to be related to anterior disc dislocation without reduction, but there was no distinct evidence of condylar destruction or collapse. They experienced sudden occurrence of occlusal change, anterior open bite in 2 patients, lateral CR-CO discrepancy in 1 patient, and anteroposterior CR-CO discrepancy in 1 patient. Also, this report is to find out if there is a relation between sudden occurrence of occlusal change and anterior disc dislocation without reduction.

Three-dimensional finite element analysis of initial tooth displacement according to force application point during maxillary six anterior teeth retraction using skeletal anchorage (골격성 고정원을 이용한 상악 6전치 후방 견인시 힘의 적용점 변화에 따른 치아 이동 양상에 관한 유한 요소법적 분석)

  • Kim, Chan-Nyeon;Sung, Jae-Hyun;Kyung, Hee-Moon
    • The korean journal of orthodontics
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    • v.33 no.5 s.100
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    • pp.339-350
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    • 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

Finite element analysis of effectiveness of lever arm in lingual sliding mechanics (Lingual sliding mechanics의 lever arm 효과에 대한 유한요소분석)

  • Kim, Kyeong-Hee;Lee, Kee-Joon;Cha, Jung-Yul;Park, Young-Chel
    • The korean journal of orthodontics
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    • v.41 no.5
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    • pp.324-336
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    • 2011
  • Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

Kinematic Analysis of T-Stop Motion by Inline Skate Rolling Speed (인라인 스케이트 활주속력에 따른 T-Stop의 운동학적 분석)

  • Han, Je-Hee;Woo, Byung-Hoon;Kim, Jeong-Goo;Kim, Tae-Whan;Kim, Sung-Sup;Kim, Eui-Hwan
    • Korean Journal of Applied Biomechanics
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    • v.20 no.4
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    • pp.355-364
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    • 2010
  • The purpose of this study was to investigate the kinematical analysis of T-stop motion by inline skate rolling speed. Six subjects were participated in the experiment(age: $35.0{\pm}3.3$ yrs, weight: $72.70{\pm}5.1\;kg$, height: $176.30{\pm}3.1\;cm$, career: $10.00{\pm}2.5$ yrs). The study method adopted 3-dimensional analysis and 2 cameras for filming to analyze the required displacement of center of mass, displacement of right and left hip joint, displacement of right and left knee joint, displacement of trunk tilt using by APAS. The results were as follows; In anterior-posterior displacement of COM, the faster rolling speed, the longer displacement at phase 2. In vertical displacement of COM, the faster rolling speed, the lower displacement. In medial-lateral displacement of COM, there was no significant on rolling speed. In angular displacement of right thigh segment, the faster rolling speed, the bigger displacement in X and Z axis. In angular displacement of left thigh segment, the faster rolling speed, the lower displacement in X axis. In angular displacement of right shank segment, the faster rolling speed, the bigger displacement in Z axis. In angular displacement of left shank segment, the faster rolling speed, the bigger displacement in X and Y axis. In angular displacement of trunk segment, the faster rolling speed, the bigger displacement in Z axis.

CT Study of Spondylolisthesis Comparison Between Isthmic and Degenerative Type (척추 전방전위증의 전산화 단층촬영 소견 : 협부형과 퇴행형의 비교)

  • Lee, Jong-Deok;Byun, Jae-Young
    • Journal of Acupuncture Research
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    • v.17 no.4
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    • pp.79-87
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    • 2000
  • Objectives : To evaluate the findings useful for differential diagnosis and associated abnormaiities of isthmic spondylolisthesis and degenerative spondylolisthesis on CT. Materials and methods : We reviewed retrospectively the CT images of 65 patients who were diagnosed spondylolisthesis during 3 years period. Our technique was 5mm slices at 5mm intervals with gantry angle to parallel the interspaces. Also reformatted sagittal views were taken. 41 patients were isthmic spondylolisthesis and 24 patients were degenerative spondylolisthesis. Resuits : Isthmic spondylolisthesis. 1. Isthmic type was more common at L5-S1. 2. The degree of anterior displacement was grade I and II. 3. The plane of defect was more horizontal than the usual facet joint. 4. The defect had an irregular shape. 5. Medial aspect of bone just anterior to defect had a small round prominence. 6. Anteroposterior elongation of the spinal canal was common. 7. Pseudobulging disk was common. 8. The most common associated abnormality was a HNP at the upper level of the defect. Degenerative spondylolisthesis. 1. Degenerative type was more common at L4-5. 2. The degree of anterior disptacement was grade I and II. 3. The Plane of facet joint was oriented obliquely instead of horizontally. 4. The posterior facet(inferior facet of superior vertebra) was anteriorly displaced. 5. Bony spur of the posterior portion of anterior facet was seen. 6. The facet joints often contain gas(vaccum phenomenum). 7. The most common associated abnormality was a HNP at the level of the displacement. Conclusions : CT is a highly accurate and most sensitive technique for recognition, differential diagnosis of isthmic and degenerative types and the detection of associated abnormalities.

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Positional and morphologic changes of the temporomandibular joint disc using magnetic resonance imaging

  • Ahn Hyoun-Suk;Cho Su-Beom;Koh Kwang-Joon
    • Imaging Science in Dentistry
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    • v.31 no.4
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    • pp.235-240
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    • 2001
  • Purpose: To evaluate displacement and morphologic changes of the temporomandibular joint (TMJ) disc in patient with internal derangement using magnetic resonance imaging (MRI). Materials and Methods: One hundred and forty five MR images of TMJs in 73 patients were evaluated. Positional and morphologic changes of the TMJ discs were assessed. Lateral or medial disc displacement was also evaluated on coronal images. Results: Among 63 discs with anterior disc displacement, 37 discs were assessed as a biconcave disc and 21 as a deformed disc. Rotational disc displacement was observed in 35 discs. Anteromedial disc displacement was observed in 29 discs, and anterolateral direction in 6 discs. Among 35 rotational displacement, 5 biconcave discs and 21 deformed discs were observed. Conclusion : Rotational and sideways displacement of TMJ discs were found to be common and an important aspect of internal derangement. This study also suggests that sagittal and coronal images of the TMJ have complementary abilities for an assessment of joint abnormality.

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The vertical location of the center of resistance for maxillary six anterior teeth during retraction using three dimensional finite element analysis (상악 6전치부의 후방견인시 저항중심의 수직적 위치에 관한 3차원 유한요소법적 연구)

  • Lee, Hye-Kyoung;Chung, Kyu-Rhim
    • The korean journal of orthodontics
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    • v.31 no.4 s.87
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    • pp.425-438
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    • 2001
  • The delivery of optimal orthodontic treatment is greatly influenced by clinician's ability to predict and control tooth movement by applying well-known force system to dentition. It is very important to determine the location of the centers of resistance of a tooth or teeth in order to have better understanding the nature of displacement characteristics under various force levels. In this study, three dimensional finite element analysis was used to measure the initial displacement of the consolidated teeth under loading. The purpose of this study was to define the location of the centers of resistance at the upper six anterior segment. To observe the changes of six anterior segment, 200gm, 250gm, 300gm, and 350gm forces at right and left hand side each were imposed toward lingual direction. For this study, two cases, six anterior teeth and six anterior teeth after corticotomy, were reviewed. In addition, it was reviewed the effects of changes on the location of the center of resistance in both cases based on different degree of forces aforementioned. The results were that : 1. The instantaneous center of resistance for the six anterior teeth was vertically located between level 4 and level 5, which is, at 6.76mm, $44.32\%$ apical to the cementoenamel junction level. 2. The instantaneous center of resistance for the six anterior teeth after corticotomy was located vertically between level 4 and level 5, that is, at 7.09mm $46.38\%$ apical to the cementoenamel junction level. 3. Changes of force showed little effect on the location of the center of resistance in each case. 4. It was observed that the location of the instantaneous center of resistance for the six anterior teeth after corticotomy was changed more than the six anterior teeth without corticotomy to the apical part, and the displacement of the consolidated anterior teeth moved further in case of the consolidated teeth after corticotomy.

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Open Reduction of an Isolated Anterior Nasal Spine Fracture: A Case Report and Review of the Literature

  • Jinwoo Park;In Sik Yun;Tai Suk Roh;Young Seok Kim
    • Archives of Plastic Surgery
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    • v.50 no.4
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    • pp.389-392
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    • 2023
  • A 14-year-old girl had a midfacial trauma event caused by hitting against an opening door and experienced discomfort and swelling of the columella and upper lip. Physical examination revealed mild tenderness on light palpation without any discomfort with upper lip movement. A computed tomography scan of the maxillofacial bones with three-dimensional reconstruction showed a fracture of the anterior nasal spine with obvious leftward displacement, mild-deviation of the caudal aspect of the nasal septum, and no sign of nasal bone fracture. Open reduction and internal fixation was performed with regard to aesthetic and functional concerns, including nasal septum deviation. The postoperative course was uneventful, and healing proceeded normally without complications. Herein, we emphasize the importance of differential diagnosis of isolated anterior nasal spine fractures in patients with midfacial trauma and clinicians' strategic decision-making in treatment modalities.