• 대한치과보철학회지
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• 제37권1호
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• pp.71-92
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• 1999

This study is to analyze the stress and displacement on the jaws during the bilateral and unilateral clenching task on three dimensional finite element model of the dentated skull. For this study, the computed tomography(G.E.8800 Quick, USA) was used to scan the total length of human skull in the frontal plane at 1.9mm intervals. The CAD data were extracted from the tomograms through digitizer(Summa Sketch III, USA) and then reconstructed by means of the spline method in the CAD program. In this project, a commercial software I-DEAS(Master Series ver-sion 3.0, SDRC Inc, USA) was used for three-dimensional stress analysis on the finite element model. which consists of articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The results are as follows. ; 1. During the bilateral clenching, each major muscle forces caused high stresses on various areas of skull: masseter muscle on articular disc and teeth ; temporal muscle on mandible and periodontal ligament ; medial pterygoid muscle on the temporomandibular joint. During the unilateral clenching, masseter muscle induced the maximum stress ; medial pterygoid muscle the minimum stress. 2. During the bilateral clenching, higher compressive stresses on articular disc were generated by the masseter muscle and higher deformation occurred on the most front outer sites. And during the unilateral clenching, temporal muscle and medial pterygoid muscle exerted their forces to twist temporomandibular joint area of the balancing side and induced a higher compressive stresses on the front outer sites of articular disc. 3. During the bilateral clenching, the masseter muscle bended the mandible outwardly, and then caused tensile stresses on the lingual surface of mandibular symphysis. And the medial pterygoid muscle caused tensile stresses on the labial surface of mandibular symphysis. 4. When each muscles were simultaneously applied on jaws, a high stress and displacement took place on mandible rather than on the maxilla. Also, a high stress and displacement took place during the unilateral clenching rather than during the bilateral clenching.

• Geomechanics and Engineering
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• 제12권6호
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• pp.919-933
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• 2017

A series of Brazilian tests under diameter compression for disc specimens was carried out to investigate the strength and failure behavior by using acoustic emission (AE) and photography monitoring technique. On the basis of experimental results, load-displacement curves, AE counts, real-time crack evolution process, failure modes and strength property of granite specimens containing two pre-existing holes were analyzed in detail. Two typical types of load-displacement curves are identified, i.e., sudden instability (type I) and progressive failure (type II). In accordance with the two types of load-displacement curves, the AE events also have different responses. The present experiments on disc specimens containing two pre-existing holes under Brazilian test reveal four distinct failure modes, including diametrical splitting failure mode (mode I), one crack coalescence failure mode (mode II), two crack coalescences failure mode (mode III) and no crack coalescence failure mode (mode IV). Compared with intact granite specimen, the disc specimen containing two holes fails with lower strength, which is closely related to the bridge angle. The failure strength of pre-holed specimen first decreases and then increases with the bridge angle. Finally, a preliminary interpretation was proposed to explain the strength evolution law of granite specimen containing two holes based on the microscopic observation of fracture plane.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.1-4
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• 2003

Purpose : The purpose of this study was to investigate the distribution and frequency of temporomandibular joint (TMJ) effusion in magnetic resonance (MR) images of patients with disc displacements. Materials and Methods: On T2 weighted MR images of 148 TMJs taken from 74 patients presenting with TMJ pain and dysfunction, we assessed the cases showing TMJ effusion, defined as an amount of fluid that exceeded the maximum amount seen in a control group of asymptomatic volunteers. The amount of TMJ fluid was graded as: I (none or minimal), II (moderate), III (marked), and IV (extensive), according to a standard set by a reference. Disc displacement categories were also recorded. Results: Of the 148 TMJs examined in this study, 52 joints (35.1%) presented with joint effusion, 24 (16.2%) showing bilateral joint effusion. 38 joints showed upper joint space effusion, 3 showed lower joint space effusion, and 11 showed both upper and lower joint space effusion. 96 joints (64.9%) had grade I joint fluid, 27 (18.2%) grade II, 15 (10.1 %) grade III, and 10 (6.8%) grade IV. 80.0% of the joints presenting with grade IV effusion showed disc displacement without reduction. Conclusion: Joint effusion was found not only in upper, but also in lower joint spaces. The higher the effusion grade, the greater the frequency of disc displacement without reduction.

• 대한치과교정학회지
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• 제23권4호
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• pp.503-527
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• 1993

This paper describes a new method to create an animal model for TMJ internal derangement in the New Zealand white rabbits and the light and electron microscopical changes of posterior attachment of them. Twenty six rabbits(2.5-3.0kg), four normal and twenty two experimental, were used. The right disc of experimental animal was displaced anteriorly without sectioning the posterior attachment and tied to the zygomatic arch with nylon not to be reduced to the original position. The left TMJ was sham-operated to be compared with its right experimental one. Normal animals were sacrificed one day and eight weeks after experiment. Experimental animals were sacrificed one day, ten days, three weeks, five weeks and eight weeks after surgery respectively. They were fixed intravenously with $2\%$ glutaldehyde under general anesthesia and the samples of them were processed for light and electron microscopic examination. The purpose of this experiment is to make a suitable animal model of disc displacement without reduction for studying and understanding the cellular and morphologic events in posterior attachment of TMJ including early changes which were difficult to be observed in human TMJs. The results of this investigation suggest the following conclusions : 1. Authors induced anterior disc displacement surgically in rabbits with new method to examine histologic changes of posterior attachment. Tissue reactions of this model seem to be similar to those observed in human disc displacement. We think this animal model for anterior disc displacement may be used to explore and evaluate objectively the effects of many treatment modalities in disc displacements. 2. The animal disease model showed inflammation at early stage(one and ten days). At this stage there were mild-to-severe mononuclear inflammatory cell infiltration, numerous newly formed vessels, vessel dilatation and engormement and many fibroblasts. 3. At middle stage(three weeks), fibrosis occurred, where fibroblasts decreased in number, but their cytoplasm was profuse indicating high activity. Collagen fibers increased in number and the tissue looked more dense. 4. At late stage(five weeks and eight weeks) showed degenerative changes including perforation of posterior attachment, disintegration of collagen fiber bundles, degeneration of fibroblasts, metastatic ossification, and dystrophic calcification.

• Imaging Science in Dentistry
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• 제33권2호
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• pp.63-70
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• 2003

Purpose: To describe the MRI findings of the retrodiskal tissue in patients presenting with TMJ internal derangement and to correlate these findings with clinical and other MRI manifestations. Materials and Methods: One hundred eighteen joints of 63 patients with TMJ internal derangement were examined by MRI. Tl-weighted sagittal MR images taken in both closed- and open-mouth were evaluated for the presence of demarcation between disk and retrodiskal tissue, the presence of low signal intensity, and the depiction of the temporal part of the posterior attachment. The results were correlated with the duration of TMJ internal derangement, the presence of pain, and other MRI findings, including the type of internal derangement, the extent of disk displacement, the degree of disc deformation, and the presence of osteoarthrosis. Results: A significant relationship between the presence of low signal intensity in the retrodiskal tissue and other MRI findings was determined. Low signal intensity on the open-mouth view was observed more frequently in patients with disc displacement without reduction, severe disc displacement and deformation, and osteoarthrosis (p<0.05). The demarcation between disk and retrodiskal tissue, and the depiction of the temporal part of the posterior attachment(TPA) were correlated neither with clinical, nor with other MRI findings. Conclusion: This study suggests that low signal intensity in the retrodiskal tissue on open-mouth MR image can be indicative of advanced stages of disk displacement.

• Imaging Science in Dentistry
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• 제31권2호
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• pp.73-84
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• 2001

Purpose: The purpose of this study was to find the relationship among the joint status, pain and effusion in patients with temporomandibular joint disorders. Materials and Methods: Materials included 406 patients (812 joints) with clinical records and bilateral TMJ MRIs in TMJ clinic, Yongdong Severance Hospital. All joints were classified in 4 groups in MR images according to the disc status of joint; normal disc position, disc displacement with reduction (DDcR), early and late stage of disc displacement without reduction (DDsR), and also 2 groups according to the bony status of joint; normal bony structure and osteoarthrosis. MR evidence of joint effusion was categorized in 4 groups according to its amount. To determine the relationship between joint pain and joint effusion, 289 patients with unilateral TMJ symptoms were selected from total materials. Result: Joint effusion was found 8.0% in normal disc position, 32.6% in DDcR, and 59.2% in DDsR (83.1 % in early state and 23.1 % in late stage). Joint effusion was found 39.7% in osteoarthrosis and 35.0% in normal bony structure. Joint effusion was more found in the painful joints (49.8%) than in the painless joints (22.4% )(p<0.001). Joint effusion in the early stage of DDsR only was more found significantly in painful joints (91.9%) than in painless joints (62.1 %) (p<0.001). Conclusion : MR evidence of joint effusion might be related to disc displacement regardless of the presence of osteoarthrosis, and the early stage of DDsR was found more frequently combined with joint effusion and joint pain.

• Journal of Oral Medicine and Pain
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• 제36권1호
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• pp.71-79
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• 2011

공률이 낮은 것으로 알려져 있다. 본 연구의 목적은 이개측두신경을 전달마취하여 수조작할 경우 변위된 관절원판의 정복에 영향이 있는지 여부 및 그 결과에 영향을 미치는 인자들을 조사하는 것이다. 비정복성관절원판변위로 진단된 112명의 환자들에 대해 수조작정복술을 시도하였으며, 그 중 35명의 환자들에서 관절원판 변위가 해소되었다. 관절원판 재위치에 실패한 77명의 환자들 가운데 이개측두신경의 전달마취 시술에 동의하는 49명(평균 연령 $34.3\;{\pm}\; 15.1$, 남자 24명, 여자 25명)에 대해 마취시술 후 수조작 정복술을 다시 시행하였다. 연령, 발병후 경과시간, 술전 능동적개구량을 포함한 요인들과 국소마취 후 수조작 정복 성공률과의 관련성을 분석하였다. 수조작만으로 정복이 되지 않았던 49명 환자 중, 이개측두신경 전달마취 후 19명(38.8%)에서 성공적으로 정복이 되었다. 국소마취 전 49명의 최대 능동적 절치간 개구량은 $25.7\;{\pm}\;6.0$ mm로서 개구가 상당히 제한된 상태였으나, 국소마취 및 수조작 후 관절원판이 성공적으로 재위치된 19명의 개구량은 $46.1\;{\pm}\;4.5$ mm로서 정상범위로 회복되었다. 연령, 발병후 경과시간, 술전 능동적개구량 인자들과 국소마취 후 수조작 정복 성공률과는 유의한 관련성이 없었다. 결론적으로 이개측두신경 전달마취는 수조작정복술과 함께 시행할 경우 비정복성관절원판변위의 정복 성공률을 향상시 키므로, 비정복성관절원판변위의 일차적인 치료 단계에서 적극적으로 활용하는 것이 권장된다.

• 대한정형도수물리치료학회지
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• 제1권1호
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• pp.49-63
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• 1995

Examination at the spine is dependent on assessment of function. At all spine levels a number of general anatomical considerations hold sway which together dictate the format of the evaluation. Because disc lesions are common and generally responsive to treatment, the examination sets out to differentiate between disc lesions and the other sources of pain as well as establishing the particular treatment that will benefit any given displacement. As elsewhere in the body, displacements give rise to certain characteristic symtoms and signs. First, the history is indicative. Second, any loose fragment in the joint restricts spinal movement in some but not all directions, producing the non-capsular pattern characteristic of internal derangement. Third, a displacement protruding posteriorly interferes with the dura mater ; apart from pain, this adversely affects the dura's normal painless mobility. Fourth, a displacement protruding laterally connects with the appropriate nerve root emerging from the dura mater. Finally, compression of the spinal cord strongly contraindicates manipulation, the primary treatment for cartilaginous displacements.

• The Korean Journal of Pain
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• 제27권1호
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• pp.86-89
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• 2014

Discal cyst is an intraspinal cyst with a distinct communication with the corresponding intervertebral disc. It is a rare condition and could present with radiculopathy similar to that caused by lumbar disc herniation. We present a patient with a large discal cyst in the ventrolateral epidural space of the $5^{th}$ lumbar vertebral (L5) level that communicated with the adjacent $4^{th}$ lumbar and $5^{th}$ lumbar intervertebral disc, causing L5 radiculopathy. We alleviated the radiating pain with selective transforaminal epidural blocks.

• 센서학회지
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• 제8권3호
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• pp.211-218
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• 1999

This paper describes the application of a coupled finite element-boundary element method (FE-BEM) to obtain the steady-state response of a piezoelectric transducer. The particular structure considered is a PZT4 disc-typed projector. The projector is three-dimensionally simulated to transduce applied electric charge on axial surfaces of the piezoelectric disc to acoustic pressure in air or in water. The directivity pattern of the acoustic field formed from the projected sound pressure is also simulated. And the displacement of the disc caused by the externally applied electric charge is shown in temporal motion. The coupled FE-BE method is described in detail.