• 대한치과보철학회지
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• 제28권1호
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• pp.123-135
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• 1990

It would be of importance to determine the neutral Tone by a resultant axis of relation on relation to the mandible in understanding the biomechanics of the mandibular movement. In this study, the neutral zone at the habitual opening and closing mandibular movements is the shape of the paths described by a minimum moving point occured as an average center of the determined instantaneous centers of rotation. Twenty, aged $23{\sim}25$, male dental students without Temporomandibular disorders and with normal occlusion clinically were selected for the study. The habitual opening and closing mandibular movements were recorded by the Gnathorecouder and analyzed by the computer program of a planer rigid body model and the determined method of a minimum moving point. The results obtained from this study were as follows. 1. The minimum moving points were placed in the body of the mandible except two subjects. 2. The mean of maximum displacements of a minimum moving point was $0.62{\pm}0.08cm$ on X-axis and $0.73{\pm}0.16cm$ on y-axis. 3. The mean of maximum displacements of a minimum moving point was $3.39{\pm}0.62cm$ 4. The position and shape of the neutral zone were determined by the position, displacements, and moving distances of a minimum moving point.

• 구강회복응용과학지
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• 제25권4호
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• pp.337-347
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• 2009

심하게 마모된 치열의 경우 마모로 인해 교합평면의 이상과 보철물을 제작할 공간이 없는 경우가 많다. 이 경우 대개 reverse curve를 보이는 교합평면을 바로잡고 보철물을 제작하기 위해 고합교경을 높여주는 과정이 필요하다. 교합고경이란 상하악 치아가 최대 폐구위에서 감합하고 있을때 상악에 대한 하악의 수직적 위치를 나타낸다. McAndrew는 고경이 변한다해도 중심위에서 전체치궁의 균일한 접촉이 이루어 진다면 치조골내에서 일어나는 remodeling 에의한 고경의 변화에도 불구하고 수정된 교합개선상태는 유지된다고 하였다. 중심위는 치료를 위한 하악위치의 참고점으로 널리 사용되어 왔다. 중심위란 하악이 해부학, 생리학적으로 안정을 이룬 상태에서 반복재현 가능한 위치이다. 본 증례에서는 심하게 마모된 치열을 지녀 보철수복을 위한 공간을 상실한 환자에서 교합고경을 증가시켜 중심위를 이용하여 처치한 치험예를 문헌고찰과 함께 보고하고자 한다.

• 대한치과교정학회지
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• 제45권2호
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• pp.59-65
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• 2015

Objective: To investigate skeletal and dental changes after application of a mandibular setback surgery-first orthodontic treatment approach in cases of skeletal Class III malocclusion. Methods: A retrospective study of 34 patients (23 men, 11 women; mean age, $26.2{\pm}6.6years$) with skeletal Class III deformities, who underwent surgery-first orthodontic treatment, was conducted. Skeletal landmarks in the maxilla and mandible at three time points, pre-treatment (T0), immediate-postoperative (T1), and post-treatment (T2), were analyzed using cone-beam computed tomography (CBCT)-generated half-cephalograms. Results: The significant T0 to T1 mandibular changes occurred $-9.24{\pm}3.97mm$ horizontally. From T1 to T2, the mandible tended to move forward $1.22{\pm}2.02mm$, while the condylar position (Cd to Po-perpendicular plane) shifted backward, and the coronoid process (Cp to FH plane) moved vertically. Between T1 and T2, the vertical dimension changed significantly (p < 0.05). Changes in the vertical dimension were significantly correlated to T1 to T2 changes in the Cd to Po-perpendicular plane (r = -0.671, p = 0.034), and in the Cp to FH plane (r = 0.733, p = 0.016), as well as to T0 to T1 changes in the Cp to Po-perpendicular plane (r = 0.758, p = 0.011). Conclusions: Greater alterations in the vertical dimension caused larger post-treatment (T2) stage skeletal changes. Studying the mandibular position in relation to the post-surgical vertical dimension emphasized the integral importance of vertical dimension control and proximal segment management to the success of surgery-first orthodontic treatment.

• Imaging Science in Dentistry
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• 제40권2호
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• pp.75-81
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• 2010

Purpose : This study is aimed to evaluate the position of mandibular foramen of mandibula prognathism patients using 3-dimensional CT images in order to reduce the chance of an anesthetic failure of the mandibular nerve and to prevent the damage to the inferior alveolar nerve during the orthognathic surgery. Materials and Methods : The control group consist of 30 patients with class I occlusion. The experimental group consist of 44 patients with class III malocclusion. Three-dimensional computed tomography was used to evaluate the position of the mandibular foramina. Results : The distance between mandibular plane and mandibular foramen, class I was 25.385 mm, class III was 23.628 mm. About the distance between occlusal plane and mandibular foramen, class I was 1.478 mm, class III was 5.144 mm. The distance between posterior border plan of mandibular ramus and mandibular foramen had not statistically significant. About the distance between sagittal plane of mandible and mandibular foramen did not also showed statistically significant. Conclusion : The result of this study could help the clinicians to apprehend more accurate anatomical locations of the foramina on the mandible with various facial skeletal types. thereby to perform more accurate block anesthesia of the mandibular nerve and osteotomy with minimal nerve damage. In addition, this study could provide fundamental data for any related researches about the location of the mandibular foramina for other purposes.

• 대한치과보철학회지
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• 제31권3호
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• pp.351-384
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• 1993

Complete denture occlusion must be developed to function efficiently and with the least amount of trauma to the supporting tissues. For the preservation of supporting tissues, it is imperative to reduce to a minimum the functional stress induced by dentures. The magnitude of the horizontal component of functional stress contributed by various occlusal teeth forms has not been studied. This study was aimed to investigate the influence of different occlusal teeth forms on the mode of distribution of the stresses in the mandibular tissue, and the displacement of lower dentures during the variant functional movement of mandible for this study three dimensional finite element analysis was used. FEM models were created using commercial software Super Sap for IBM 32 bit computer. The model was composed of 3380 brick elements and 4346 nodes. The results were as follows. 1. The magnitude of stress was similar between two models in centric occlusion, in the case of anatomic model, the stress was concentrated on the buccal side of alveolar ridge beneath the bicuspids. 2. During the protrusive movement, the increasing of stress from the posterior to anterior part of mandible was seen in the case of anatomic model. 3. During the lateral movement, the stress of anatomic model was greater than that of nonanatomic model. 4. The stress of anatomic model was concentrated on the anterior region of residual ridge during the lateral movement. 5. In the case of anatomic model the anterior part of denture was displaced severely at the centric and lateral position, but the denture of nonanatomic model was displaced minutely at the protrusive and lateral position.

• 구강회복응용과학지
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• 제17권4호
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• pp.245-256
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• 2001

The purpose of this study is to analyze the mechanical stress and displacement on the jaws during the simulated bilateral clenching task on the three-dimensional finite element model of the dentated skull with unilateral molar loss. 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 2.0mm intervals. The fully assembled finite element model consists of the articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The FE model was used to simulate the bilateral clenching in intercuspal position. The loading condition was the force of the masseter muscle exerted on the mandible as reported by Korioth et al. degrees of freedom of the zygomatic region where the masseter muscle is attached were fixed as restraints. In order to reflect the actual action of the muscles force, the displacement of the region was attached where the muscle is connected to the temporal bone and restraint conditions were given values identical to values at the attachment region of the masticatory muscle but with the opposite direction of the reaction from when the muscle force is acted on the mandible. Although the mandible generally has higher displacement and von Mises stress than the maxilla, its mandibular corpus on the molar-loss side has a higher stress and displacement than the molar-presence side. Because the displacement and von Mises Stress was the highest on the lateral surface of mandibular corpus with molar loss, the stress level of the condyle on the molar-loss side is greater than that of the molar-presence side, which in turn caused the symphysis of the mandible to bend. In conclusion, the unilateral posterior bite collapse with molar loss under para-functional activities such as bruxism and clenching can affect the stress concentration on the condyle and mandibular corpus. It is therefore necessary to consider the biomechanical function of dento-skeleton under masticatory force while designing the occlusal scheme of restoration on alveolar bone with the posterior collapse.

• 대한치과교정학회지
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• 제29권1호
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• pp.23-35
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• 1999

한국인 7세-17세 아동의 두개저, 상악, 하악의 사춘기 성장 양상을 파악해 보고자 남자 251개, 여자 286개의 측모두부계측방사선 사진을 이용, 10개의 계측점과 16개의 계측항목을 설정하고 계측항목에 대한 계측치와 각 연령별 년간 누년차를 산출한 다음 이들간의 통계적 유의성을 검증하였으며 각 계측항목을 두개저, 상악, 하악의 세군으로 분류하고 또 남녀별로 분류하여 비교함으로써 다음과 같은 결론을 얻었다. 1. 한국인 성장기 아동에 있어서의 성장은 남자 아동에 비해 여자 아동이 빠른 시기에 일어났다. 2. 두개저, 상악골, 하악골 모두 사춘기 성장을 나타내었으나 두개저의 성장은 안면골 성장에 비해 상대적으로 작았다. 3. 두개저 성장에 있어서 전두개저 길이의 증가에 비해 중두개저 및 후두개저의 길이 증가가 현저했으며 사춘기 성장증가(circumpuberal growth spurt) 양상도 보다 명확했다.4. 상악골의 전하방 이동은 상악골 자체의 길이 성장과 상악골 주위 봉합부의 성장에 따른 변위가 종합된 결과로 두개저에 대한 상악골의 상대적 위치를 나타내는 Ar-ANS와 Ar-Pr이 상악골 자체의 길이 성장을 나타내는 ANS-PNS보다 많은 성장량을 보였다. 5. 하악골은 수평 성장량에 비해 수직 성장이 약간 크게 나타났으나 유의할 수준은 아니다. 6. 상악 치조골과 하악 치조골은 유치 탈락후 영구치 맹출시기에 최대 성장률을 보인후 감소하는 경향을 보이지만 하악 치조골의 수직성장에서는 사춘기 성장증가가 관찰되었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제23권3호
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• pp.263-269
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• 2001

하순 및 하악골 정중열은 매우 드문 선천성 기형으로 , 하순절흔에서부터 하악은 물론 경부, 흉부까지 연장되어 다양하게 나타날 수 있으며, 원인은 확실하지 않으나 정중부로의 중배엽의 침투 실패, 하악돌기의 유합부전 그리고 외부 요인들이 논의되고 있다. 치료방법 및 시기에 관해서는 임상소견이 다양하고 증례가 드물기 때문에 많은 논란이 있어왔다. 그러나 현재의 경향은 연조직 기형은 연하 및 발음의 기능적 장애를 예방하기 위하여 가능한 조기에 치료하며, 악골고정을 위한 강선 결찰 혹은 골이식술은 사춘기 후로 미루는 추세이다. 본 교실에서는 저작 장애를 주소로 내원한 8세 여자 환자의 임상소견에서 하악골 정중열과 하순의 수술로 인한 반흔조직 및 하순에서부터 치조골을 가로지르는 섬유성 소대 등을 발견할 수 있었으며, 하악의 정중열을 장골 이식을 이용 하여 양호한 결과를 얻을 수 있었으며, 추후 하순과 순. 설측 전정의 연조직 기형은 심미성과 기능 향상을 위해 부가적인 술식이 필요하리라 생각된다.

• The Korean Journal of Physiology
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• 제3권1호
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• pp.33-44
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• 1969

Electoromyographic studies were performed on the action of the muscles of the temporomandibular joints following exfoliation of the deciduous teeth. The subjects examined, being 50 children. between the age of 6 and 13 years, divided into 5 groups. They were; 1) Deciduous dentition were complete in the first group. 2) Deciduous incisors were missing in either upper or lower jaw in the second group. 3) Deciduous canine and molars were missing in the left side of either upper or lower jaw in the third group. 4) Deciduous canine and molars were missing in the right side of either upper or lower jaw in the fourth group. 5) Permanent dentition completed in the fifth group(except third molars). Electromyogram was recorded with 4 channel polygraph (Grass model VII modified for 7P3). Electrodes which were the cup-typed gold discs, 9 millimeters in the diameter, were located on the anterior, middle and posterior lobes of the temporal muscles, and also on the superficial and deep layers of the masseter muscles. Paired electrodes were held by electrode cream so that they were pressed on the skin surface at right angle, adhesive tape being used to anchor them. The distance of the pair electrodes was about 5 millimeters. The results obtained were as follow: 1) In rest position of mandible; All groups showed slight, electrical activities in the muscles involved, but in the middle lobe of temporal muscle they were slightly higher. 2) In molar occlusion of mandible; High activity-anterior lobe of temporal muscle and superficial layer of masseter muscle. Moderate activity-deep layer of masseter muscle. Low activity-middle and posterior lobes of masseter muscle. There were no differences among the first, the second and the fifth groups. In the third group the muscle activity was weaker than that of the right, and in the fourth group opposite characteristics was revealed. 3) In incisal bite of mandreble; Hight activity-superficial layer of masseter muscle. Modertae activity-deep layer of masseter muscle. Low activity-anterior, middle and posterior lobes of temporal muscle. The first, the third, the fourth and the fifth groups showed no differences but the second group showed less activity than those of others. 4) In protrusion of mandible; High activity-deep layer of masseter muscle Moderate activity-superficial layer of masseter muscle. Low activity-anterior, middle and posterior lobes of temporal muscle. In the first, the fourth and the fifth groups, there were no differences in the activities, but the second group showed less activity than the others. 5) In retrusion of mandible; High activity-deep layer of masseter muscle. Moderate activity-superficial layer of masseter muscle. Low activity-anterior, middle and posterior lobes of temporal muscle. In the first, the third, the fourth and the fifth groups, there were no differences but the second group showed less activity than the others. 6) In lateral excursion of the mandible (either direction); High activity-posterior lobe of temporal muscle. Moderate activity-anterior and middle lobes of temporal muscle. Low activity-superficial and deep layers of masseter muscle. The muscle action potentials were weaker than those of the right side in the third group and vice ver'sa in the fourth group. 7) In chewing movement; Temporal muscle activities were higher than those of masseter, especially in the middle lobe of temporal muscle the activity was highest. Right side muscle activities were higher than those of the left in the third group and, on the contrary, the left side was dominant over the right in the fourth group.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권1호
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• pp.1-6
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• 2002

When bilateral sagittal split ramus osteotomy or mandibular angle reduction are carried out, we have to consider the position of inferior alveolar nerve. For bone splitting or resection using a saw or an osteotome, the bucco-lingual position of the inferior alveolar nerve plays an important role in the preventing perioperative complications such as paresthesia or anesthesia. Because it is rare to find literatures concerning the mean anatomic position of the inferior alveolar nerve in Koreans, we investigated 30 patients who underwent to take CT and orthopantomogram for implant surgery, and evaluated the bucco-lingual position and vertical relationship of the inferior alveolar nerve at the mandible. The results showed that the distance between inferior alveolar nerve and buccal plate was the farthest at mandibular second molar ($7.1{\sim}7.4mm$) and the nearest at mandibular angle area ($4.4{\sim}4.8mm$). But it was no statistical relationship between the bucco-lingual postion of inferior alveolar nerve on the CT and its vertical position on the OPT. In conclusion, the results suggest that a careful surgical procedure is needed at the mandibular angle area to avoid a nerve damage and there are sufficient bone materials at the mandibular second molar are for bilateral sagittal split ramus osteotomy or mandibular angle reduction or plate fixation. And OPT is not usefull for the evaluation of a relative bucco-lingual position of inferior alveolar nerve in relation to its vertical postion on the OPT.