• Archives of Plastic Surgery
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• 제32권5호
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• pp.589-592
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• 2005

Since G.N. Hounsfield's clinical use of computed tomography in 1971, digital imaging technique using computers has shown an eye opening progress. Progress has made 3-dimensional understanding of not only facial bones but muscles and other connective tissues possible through 3-dimensional reconstruction of preexisting tomographical images. Also, quantitative analysis of density, distance, volume has become possible, allowing objective analysis of preoperative and postoperative states through imaging. The authors measured the masseter muscle volume of 20 normal individuals and 8 female patients through 3-D reconstructive CT imaging and made a statistical analysis of the measurements. The method used in our study may be applied to the diagnosis of disease causing the change of the facial volume and presurgical design as a useful tool to provide objective information on the evaluation of surgery outcome.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권3호
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• pp.259-266
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• 2005

The function of the masseter and anterior temporal muscles was assessed by electromyography in 30 patients with mandibular prognathism (20 patients with facial asymmetry and 10 patients without facial asymmetry) before orthognathic surgery and 4weeks afterwards. Electromyogram(EMG) recordings were made during resting, clenching and swallowing. We compared with right-left difference of this recording and asymmetry index before and after orthognathic surgery. The result of this study was as follows. 1. There was no significant right-left difference in muscle activities of masticatory muscles both asymmetric groups and controls and many variable change after orthognathic surgery.(P>0.05) 2. The mean electric activity of the masticatory muscles was found to have decreased during more clenching than resting, but there was no statistically significant difference because of individual difference of measuring values.(P>0.05) 3. The asymmetry index of masticatory muscles in asymmetric groups was significantly greater during clenching compared with controls.(P<0.05) In conclusion, no right-left difference of muscle activities was found in patients with facial asymmetry before orthognathic surgery and 4weeks afterwards. Not only muscular functioning but also many other factors, such as occlusion, temporomandibular joint disorder and trauma, probably affect facial asymmetry and will be analyzed in future studies. And we will need long term follow-up after orthognathic surgery.

• Journal of Oral Medicine and Pain
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• 제13권1호
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• pp.43-52
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• 1988

The author studied masticatory muscle activity and bite force in normal persons without Temporomandibular Disorders(TMD) signs and symptoms, The number of subjects was 15, and the age of them was from 22 to 25 years. Electromyography was used to record the muscle activity in tapping and clenching movement with or without occlusal splint. 3 splints were made from 3 different mandibular position, that if, centric occlusion position, Rocabado's mandibular rest position, Dawson's centric relation position. The thickness of splint was 3.0-3.5㎜ at molar region. The muscle examined were Masseter and Anterior Temporalis attached with surface electrodes and the device used to measure the EMG level was Bioelectric processor Model EM2. After recording the EMG, the author measured the bite force level in clenching movement with bite force meter Model MPM-3000 in the dame position used in the EMG experiment. The obtained results were as follow : 1. With occlusal splints insetion, the amount of decreased muscle activity in Anterior Temporalis was more than those in Masseter. 2. In the three maxillomandibular relationships with occlusal splints, Masseter showed slightly increased level of muscle in centric occlusion but Ant. Temporalis showed decreased level of muscle activity reversely in that position. 3. Muscle activities between Rocabado's rest position and Dawson's centric relation position were generally similar whatever the muscles or the movements the author examined. 4. Bite force in clenching movement increased with splints insertion, especially with the splint registered in centric occlusion position.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권5호
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• pp.423-426
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• 2010

Hemangioma is a benign vascular proliferation. Intramuscular hemangiomas are rare, accounting for less than 1% of all hemangiomas, and occur normally in the trunk and extremities. Approximately 10-20% of intramuscular hemangiomas are found in the head and neck region, most often in the masseter muscles. The typical clinical characteristic is a painful soft tissue mass without cutaneous changes. The suggested treatment is a surgical excision. We report a case of an intramuscular hemagnioma of the masseter muscle. The patient was a 56 year old male who visited our clinic complaining of left facial swelling after 2 years of follow up at a different clinic. After magnetic resonance imaging (MRI), the mass was excised under general anesthesia. The biopsy revealed the mass to be an intramuscular hemangioma. We report the clinical and pathological characteristics as well as the treatment of a case of an intramuscular hemangioma of the masseter muscle.

• 대한치과보철학회지
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• 제26권1호
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• pp.99-111
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• 1988

The purpose of this study was to investigate the influence of the occlusal interference on the activity of anterior temporal and masseter muscles during maximal biting. In seven subjects, cast hard gold cap providing new occlusal surface approximately 0.5mm above its occlusal level was cemented on the mandibular right first molar during aquired experimental period. EMG recordings were taken bilaterally during one second hardest possible clenching four times. This procedure was done not only before, immediately after, 48 hours after and one week after cementation of interfering crown but also immediately after and one week after removal of occlusal interfering crown. The results were as follows : 1. Immediately after cementation of interfering crown, the activity was significantly decreased in all muscles studied. 2. One week after cementaion of interfering crown, the lowest muscle activity was recorded. But clinical sign and symptoms were significantly subsided. 3. Immediately after removal of interfering crown, the activity was increased in all muscles studied. 4. One week after removal of interfering crown, the activity of masseter muscles was increased to the level of before cementation of interfering crown. 5. There was no significant activity difference between right and left in the muscle studied. 6. Masseter muscle activity showed significant change than anterior temporalis with the unilateral mandibular posterior tooth interference.

• 구강회복응용과학지
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• 제23권1호
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• pp.11-19
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• 2007

There are have been reports that the distribution of electromyographical(EMG) activity is determined in a predictable manner by both the location and number of occlusal contacts. However, these reports placed an emphasis on whole dentition. Inclined plane contacts in the frontal plane are classified as A-, B- or C-types. Objectives: The aim of this study was to evaluate the relation between occlusal tooth contact patterns and EMG activity of masseter muscle during maximum voluntary clenching. Methods: Fifteen healthy human subjects(Mean age; 25.3 years) volunteered to participate in this study. Acrylic resin overlays were fabricated for upper 2nd premolars and 1st molars bilaterally, and offered 3 types(A-, B- and AB- type contact). EMG activity of the masseter muscles was recorded bilaterally during maximum voluntary clenching. Statistical analysis was performed using the one-way ANOVA. Results: The group with a A-type contact showed a statistically lower EMG activity of masseter muscle than that of natural group(p<0.05) and that of B- and AB- type groups(p<0.01) on both upper 2nd premolars and upper 1st molars. Conclusions: These results suggest that occlusal tooth contact patterns have an influence on EMG activity of masseter muscle during maximum voluntary clenching.

• 대한치과교정학회지
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• 제14권1호
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• pp.53-65
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• 1984

The purpose of this study was to investigate the histopathological change and adaptation process of the mandibular joint of the rat by muscle alteration. For this study, one hundred and twenty eight rats of 25 - and 60 - day old of age were used. Unilateral and bilateral detachment, with anterior positioning of the Masseter muscle, was performed under anesthesia. The animal was sacrified 10, 20, 50, 80 days postoperatively. This alteration in muscle function led to change in neuromuscular activity and demonstrated the adaptive nature of the condyle cartilage to functional demand. The results were as follows : 1. In the right muscle detached group, operated at 25 days of age, marked decrease on the chondroblastic zone was found in the condyle head on the right side of animals examined 10 days postoperatively. Comparing with the control group, no difference was found on the chondroblastic zone in the condylar head of animals examined 20, 50 and 80 days postoperatively. 2. In the bilateral muscle detached group, operated at 25 days of age, the chondroblastic zone was slightly decreased in the anterior parts of condylar head of animals examined 10 days postoperatively. 3. In the unilateral and bilateral muscle detached group, operated at 60 days of age, no significant change was found in the mandibular joint regardless of the post operative experimental periods. 4. Under Toluidine blue staining, slightly decreased metachromasia was found in the condyle head on the right side of unilateral experimental animals, operated at 25 days of age and examined 10 days postoperatively. 5. Under Masson's trichrome staining, increased metachromasia was found in the condyle head on the right side of unilateral experimental animals, operated at 25 days of age and examined 10 days postoperatively. In summary, the condyle of the rat could respond to changes in neuromuscular activity depend on the level of maturation of the tissue, because the endochondral bone formation of the condyle of the rat was almost ended within 3 months.

• Journal of Oral Medicine and Pain
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• 제38권3호
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• pp.261-266
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• 2013

근막동통은 국소적인 통증과 촉진시 근 압통을 보이면서 근막 발통점이 존재하는 것이 특징인 근육질환이다. 본 증례에서는 야간 이갈이를 호소하는 환자의 임상검사에서 촉진을 통해 측두근 전방 부위의 잠재성 발통점을 확인하였고, 양측의 측두근과 교근에 대해 표면 근전도 검사를 시행한 결과, 이환된 측두근에서 수축 후 근과민성, 이완 지연 및 근피로 가속과 같은 소견을 얻을 수 있었다. 표면근전도 검사는 저작근의 비정상적인 기능을 확인할 수 있으므로 근육성 측두하악장애의 평가에 도움이 될 수 있다.

• 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.

• 대한치과보철학회지
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• 제27권2호
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• pp.37-52
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• 1989

The purpose of this study was to investigate the relationship between sternocleidomastoid (SCM) and masseter muscles during occlusal functions by means of EMG recordings of examined muscles. For the study, eighteen normal subjects were selected and the Bio-electric Processor EM2 (Myo-tronics Research, Inc., U.S.A.) with the surface electrodes was used to record the EMG activity from the right and left middle of masseter and insertion of SCM of each subject during right and left gum-chewing and isometric contraction by changing the biting force at right eccentric position of jaw. The amount of biting force ranged from 5 to 70kg during isometric contraction were measured by use of Jaw Force Meter. (Nihon Koden Kogyo, Japan.) The results were as follows: 1. The activity onset of SCM and masseter on the same side was almost at the same time, and integrated EMG values of two muscles on the chewing side were higher than the same named muscles on the non-chewing side during gum-chewing. (p<0.01) 2. The regression correlation was not present between both masseters (p>0.05), but between both SCM muscles or muscles of two kinds on the chewing or non-chewing side. ($p{\leqq}0.05$) 3. The integrated EMG value of SCM on chewing or non-chewing side were about 10 percent of that of ipsilateral masseter. 4. Mean voltage of each examined muscles were almost proportional to biting force during isometric contraction and the slope of voltage/biting force line was steepest at the ipsilateral masseter, followed by contalateral masseter, ipsi- and contra-lateral SCM muscles. 5. Mean voltage of ipsilateral masseter was highest during isometric contraction, followed by ipsilateral masseter, contra- and ipsi-lateral SCM muscles.