• 대한치과보철학회지
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• 제28권2호
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• pp.175-182
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• 1990

This study was performed to investigate the influence of occlusal change on the masticatory muscle activity. 8 students without any symptom of T.M.J. dysfunction, any history of prosthodontic or orthodontic treatment on dental college of WonKwang Univ. were participated in this study. The activity of masseter and anterior temporal muscles were measured by bioelectric processor(EM2, Myotronics, Inc., U.S.A.) during voluntary maximal clenching on natural teeth, by splint with bilateral posterior surface contact, by splint with unilateral posterior surface contact, and by splint without unilateral posterior teeth contact. The obtained results were as follows ; 1. The loss of posterior contact on noe side resulted in change of the activity of anterior temporal and masseter muscle during clenching on ipsilateral side, but there was no change of muscle activity on contralateral side. 2. The activity of anterior temporal and masseter muscle during clenching were not affected by the pattern of occlusal contact. 3. There were no difference between the activity of anterior temporal and masseter miuscle during clenching by natural teeth and by occlusal splint.

• 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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권3호
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• pp.229-237
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• 2000

According to the functional matrix theory, Delaire proposes that individual occlusal plane was determined by variable effects of teeth, maxilla, mandible, cranium, cranial base and soft tissue matrix including the orofacial musculature. and that there is the ideal occlusal plane determined by the most proper spatial position of maxilla and mandible, functionally and esthetically. This study was designed to find out the relation between Delaire's ideal occlusal plane and muscle activity of masticatory muscles in individuals who have normal maxillo-mandibular relationships. Lateral cephalometric radiographs were taken and his/her individual occlusal plane and ideal occlusal plane were analyzed with Delaire's architectural and structural craniofacial analytic method. For evaluation of muscle activities of masticatory muscles, electromyography of anterior temporal muscle, superficial masseter muscle, and anterior belly of digastric muscle was recorded in fifty Korean normal Angle class I occlusion individuals. According to the average value of ideal occlusal plane, fifty normal Angle class I occlusion individuals were classified into three groups: Ideal occlusal plane group(I group), hyperrotation group(I+ group) and hyporotation group(I- group). The result of this study was as follows: 1. The results of Delaire's architectural and structural craniofacial analysis of lateral cephalography of the fifty Korean normal Angle class I occlusion individuals are that twelve persons(24%) have consistent or parallel with ideal occlusal plane and the average of angular difference was $1.22^{\circ}{\pm}3.69^{\circ}$. 2. There is no significant difference in muscle activities of masticatory muscles during resting(p<0.05), but significant increases of muscle activity of ipsilateral anterior temporal and masseter muscle, contralateral anterior belly of digastric muscle during unilateral chewing and of anterior temporal and masseter muscle during bilateral clenching(p<0.05). 3. To find out the effect of the angular difference between Delaire's ideal occlusal plane and real occlusal plane to muscle activity, muscle activities of masticatory muscles were compared with three groups in each other; I group, I+ group and I- group. The results were no significant differences during resting, unilateral chewing and bilateral clenching.(p>0.05) 4. Although there is no significant differences of masticatory muscle activities among the three groups, the fact that increasing tendency of masseter muscle activity of ideal occlusal plane group(I+) than those of any other groups(I+ and I-) during bilateral clenching was noted. There is only the implication that occlusal plane makes some effects on masticatory muscle activities, espacially that of masseter muscle during bilateral clenching. In conclusion, the hypothesis that occlusal plane is one of the factors which affect the muscle activities of masticatory muscles and that anyone whose occlusal plane consistent with Delaire's ideal occlusal plane has an extraordinary functional advantage in masticatory muscle function cannot be proven with electromyography methods.

• Archives of Plastic Surgery
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• 제32권3호
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• pp.311-313
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• 2005

Generally, many Asian women tend to dislike the square jaw, as they believe it makes the face look wider, giving a stubborn and strong impression. Contouring of the mandible is therefore a relatively common aesthetic procedure among Asians. These days, the use of botulinum toxin for contouring of the lower face offer simple alternative to surgery. Motor point, which is the site over a muscle where its contraction may be elicited by a minimal intensity short duration electrical stimulus, is the optimal injection point of botulinum toxin. Study was undertaken to identify the location of motor point of the masseter muscle and the skin surface landmark. First, the thickest point of the masseter muscle was inspected through palpation and inspection by 3 different individual plastic surgeons and then compound muscle action potentials(CMAPs) of masseter muscle in 15 health volunteers were recorded using EMG. For the localization of the measured points, line between lateral canthus to the mandibular angle was used. Location of motor points were mapped to skin surface from lateral canthus in a percentage of the distance along the landmark line and in distance in millimeters. The clinical injection point was located at 71.69 percentile and 7.3 mm of the landmark line. The motor point test was located at 72.54 percentile and 7.1 mm of the landmark line. The depth of motor point was 16mm. There was no statistically significant difference between the clinical injection point and the motor point. We conclude that surface mapping of motor point of the masseter muscle would increase accessibility and accuracy in botulinum toxin injection for contouring of the lower face.

• 대한치과교정학회지
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• 제31권2호통권85호
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• pp.225-236
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• 2001

일반적으로 골의 형태와 구조는 부착 근육의 활성과 밀접한 관련이 있다고 알려져 있으며,특히 악안면 형태와 저작근 기능과의 관계는 많은 임상 및 동물 실험을 통해 연구되어 왔다. 초음파검사는 임상적 적용이 용이하고 비용이 저렴할 뿐만 아니라 환자에 대한 유해성이 적어 의학분야의 여러 영역에서 널리 이용되고 있다. 이 연구의 목적은 교근의 두께와 악안면 골격 형태와의 상관성을 평가하는 것으로, 강릉대학교 치과대학 남학생 35명과 여학생 15명을 대상으로 하였다. 교근의 두께 측정에는 7.5MHz의 고해상도 직선 탐촉자에 의한 초음파진단장치가 사용되었고, 악안면 골격 형태의 결정은 측방 두부계측방사선사진 분석을 통해 이루어졌다. 이상의 계측치로부터 얻어진 결론은 다음과 같다. 1 남자에서 교근의 평균 두께는 안정 상태에서는 13.8${\pm}$1.71mm, 최대 교합 상태에서 14.8${\pm}$1.77mm였으며 여자에서는 안정 상태에서 11.6${\pm}$1.58mm, 최대 교합 상태에서 12.4${\pm}$1.47mm로 나타났다. 2. 교근의 두께는 남녀모두 안정 상태보다 최대 교합 상태에서 유의하게 증가하였다(P<0.05). 3. 교근의 두께는 안정 상태와 최대 교합 상태 모두에서 남자가 여자보다 유의하게 두꺼웠다(P<0.05). 4. 교근의 두께는 남자에서 안정 상태와 최대 교합 상태 모두 하악평면각과는 음의 상관 관계가 있고 하악지 고경, 전두개저 길이와는 양의 상관 관계가 있음을 알 수 있었다(P<0.05). 5. 여자에서는 교근 두께와 유의한 상관 관계가 있는 두부계측방사선사진 분석 항목을 찾을 수 없었다(P<0.05). 이로써초음파검사는 악골 근육의 기능을 평가하는 전통적인 방법에 대해 추가적인 정보를 제공해 줄 수 있을 것으로 사료된다.골 상실 증가에 따른 압하시 pure intrusion을 위한 후방견인력 변화는 다음과 같다. 1) 2 전치군과 4 전치군의 후방 견인력은 6 전치군의 후방 견인력에 비해 낮게 나타났다. 2) 치조골이 상실됨에 따라 각 치아군 후방견인력은 증가됨을 보였다. 4. 상악 전치부 치아군과 치조골 높이에 따른 저항중심의 수평적, 수직적 위치간 상관관계는 다음과 같다. 1) 2 전치군일 때, 치조골 상실에 따른 저항중심의 수직적 위치변화에 대한 수평적 위치 변화가 가장 크게 나타났다. 치아 수가 증가할수록 치조골 상실에 따른 저항중심의 수직적 위치 변화에 대한 수평적 위치변화는 작아지는 경향을 보였다. 2) 치조골 상실량이 커짐에 따라서는, 치아 수에 관계 저항중심의 수직적 위치변화에 대해 수평적 위치변화가 커졌다.라 일관성 있게 감소하였고, 제거속도는 Cu가 다른 원소에 비해 빨랐다. 제거속도는 FW 3개 수조 중 FW5&6에서 세 원소 모두 가장 느렸고, SW 3개 수조 중에서는 SW1&2에서 가장 빨랐다. SW와 FW간 제거속도 차이는 세 원소 모두 명확치 않았다 Cr은 FW에서 전반적으로 감소하는 경향을 보였지만 SW에서는 실험 초기에 감소하다 24시간 이후에는 증가 후 일정한 양상을 보였다. Pb은 FW에서 전반적으로 감소했지만 SW에서는 초기에 급격히 증가 후 다시 급격히 감소하는 양상을 보였다 Pb 또한 Cu, Cd, As와 마찬가지로 SW1&2에서 제거속도가 가장 빠르게 나타났다. FW 상층수 중 Hg는 시간에 따라 급격히 감소했고, 제거속도는 Fw5&6에서 가장 느렸다. 이러한 결과에 근거할 때 벼가 자라고 있고 이분해성 유기물이 풍부한 FW1&2, FW3&4 토양과 상층수에서는 유기물의 분해 활동이 활발하였지만, 벼가 경작되지 않는 FW5&6과 SW 에서는 유기물이 상대적으로 결핍되어 유기물의 분해활동이 적었을 것으로 판단된다.

• Journal of Oral Medicine and Pain
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• 제10권1호
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• pp.105-112
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• 1985

The author has studied the duration of silent period of the masseter muscle using electromyography in order to obtain the information that is necessary to diagnose the patients with TMJ dysfunction syndrome objectively. The 55 normal subjects and the 40 patients with TMJ dysfunction syndrome were selected for this study. The results were as follows : Duration of silent period of the masseter muscles in normal subjects were 24.4 msec in males, 24.0 msec in females, and mean of $24.2\pm3.19$ msec. Duration of silent periods of the masseter muscles in patients with TMJ dysfunction syndrome were 39.4 msec in males, 41.3 msec in females, and mean of $40.5\pm7.01$ msec. There was no significant difference of the duration of silent periods between in the right and the left side of the masseter muscles, and between in the males and the females (p>0.05). Duration of silent periods of the masseter muscles in patients with TMJ dysfunction syndrome were significantly more prolonged than those in normal subjects (p<0.01). Borderline of silent periods of the masseter muscles between in normal and patients with TMJ dysfunction syndrome was 31.5 msec.

• 대한치과보철학회지
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• 제25권1호
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• pp.213-226
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• 1987

The purpose of this study was to standardize and classify the coordination pattern among the left and right masseter and anterior temporal muscles, in terms of integrated EMG values per stroke during gum chewing in normal subjects. In this study, 20 normal subjects were selected to chew a piece of gum and integrated EMG from middle portion of the masseter and anterior temporal muscles on both sides were recorded 20 times during each of the right and left chewing respectively. And the Bioelectric Processor Model EM2 (Myo-tronies Research, Inc., U.S.A.) with the surface electrodes was used to record the EMG activity during all experimental procedures. The results were as follows; 1. In all subjects, the chewing side masseter muscle was predominantly active among the four muscles examined. 2. The integrated EMG value of the middle of masseter muscle was significantly predominant than those of the anterior temporal muscle (p<0.0001) on the chewing side, but no significant predominant was observed on the nonchewing side (p<0.98). 3. In comparison with same muscles on the chewing and nonchewing side, low correlation coefficient was found between the middle of masseter muscles (R=0.317), but high correlation coefficient was found between the anterior temporal muscles (R=0.738). Between two muscles on the same side, there were significant correlation in the chewing (R=0.557) and nonchewing side (R=0.625). 4. In the coordination patterns among four muscles examined, distinct individual differences were found, but in an identical subject one fixed pattern appeared with significant reproducibility.

• Journal of Oral Medicine and Pain
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• 제13권1호
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• pp.85-93
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• 1988

The author studied maximum clenching EMG activities of temporalis anterior and masseter muscle during canine guidance and centric occlusion. It was performed before and after anesthesia of maxillary and mandibular canines. The 22 normal subjects (15 males and 7 females) who had healthy maxillary and mandibular canines were selected. Their occlusal contact scheme was canine guidance during movement and they did not have temporomandibular disorder. The results were as follows : 1. The maximum clenching EMG activities of temporalis anterior and masseter muscle during guidance were less than those during centric occlusion. 2. After left maxillary and mandibular canines were anesthetized with 2% lidocanine with 1:100,000 epinephrine, the maximum clenching EMG acivities of temporalis anterior and masseter muscle during left canine guidance were greater than those before anesthesia of left maxillary and mandibular canines(p<0.01) 3. The maximum clenching EMG activities of temporalis anterior and masseter muscle during right guidance were not significantly different between before and after anesthesia of left maxillary and mandibular canines(p>0.05).

• 대한두경부종양학회지
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• 제33권1호
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• pp.79-83
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• 2017

Hemangioma is the most common benign tumor in neonatal and infant stage. In the head and neck region, the lesion mostly occurs in the masseter, trapezoidal or sternocleidomastoid muscle. Due to its rarity and non-specific symptoms, it is difficult to diagnose precisely. Intramuscular hemangioma can be misdiagnosed as sialolithiasis of the parotid gland. There are several treatment options for hemangiomas such as sclerotherapy, radiotherapy, embolization, and surgery. Of all these, definitive surgical resection is considered most effective in preventing future recurrence. Here we report a case of intramuscular hemangioma that was detected in the patient's right masseter muscle which was initially misdiagnosed as parotid sialolithiasis and was consequently managed with surgical resection.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.31.1-31.5
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• 2017

Background: Dystrophic calcification can occur in any soft tissue with the absence of a systemic mineral imbalance and is often associated with trauma, infection, or inflammation. It is easily found in the site of the heart and skeletal muscles and rarely appears in the head and neck area. Case report: We present a rare case of multiple calcified masses in the left masseter muscle of a 26-year-old female with a history of trauma in the area. In computed tomography, multiple radiopaque masses were observed inside the left masseter muscle and blood test results were normal. The calcified masses were diagnosed as dystrophic calcification and removed by surgery without any complications. Conclusion: Different types of calcifications may occur in the cheek area, and they need to be distinguished from dystrophic calcification. Thorough clinical examination and history taking is required together with blood testing and radiographic examinations.