• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.3
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• pp.300-305
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• 2008

Purpose: The purpose of our study was to evaluate the volume of pre- and post operative masseter muscle and bite force in mandibular prognathic patients treated with SSRO with the use of the 3D CT imaging technique and occlusal force meter. Materials and methods: The study group consisted of 12 patients with mandibular prognathism (5 males and 7 females) who underwent mandibular setback surgery (BSSRO) in the Department of Oral and Maxillofacial Surgery, Samsung medical center. Bite force was measured at pre op, post op 3, 6 and 12 months by occlusal force meter(GM10, Nagano Keiki, Japan) The preoperative CT examination of subjects was performed between one month prior to operation and one year after to operation. And muscle volume was measured. Result: As compared to preoperative measurements at 1 year postoperatively the masseter & internal pterygoid muscle volume were diminished (p<0.05) The bite force steadily recovered, so at postoperatively 6 months reached the preoperative level. And at 1 year after operation, the maximum bite force was significantly greater than preoperative levels. No significant correlation was presented between masseter muscle and bite force (p>0.05), internal pterygoid muscle and bite force (p>0.05). Conclusion: In this study, the results showed that volume and bite force of the masticatory muscles decreased significantly immediate after orthognathic surgery for mandibular set-back. However, reduction of maximum bite force disappears within 6 months after surgery.

• Journal of Oral Medicine and Pain
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• v.25 no.1
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• pp.117-128
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• 2000

The present study explored the influence of temporomandibular disorders(TMD) with anterior open bite on swallowing. Fifteen subjects with anterior open bite(group A), 9 subjects with anterior open bite and TMD(group B), and 24 subjects without malocclusion or TMD symptoms (group C) were included. BioPAK system(Bioresearch Inc., Milwaukee, WI, USA) was used to record the muscle activities of anterior temporal, masseter, sternocleidomastoid(SCM) and anterior digastric muscles during maximum clenching and swallowing. Positional change of the mandible during swallowing was also recorded using the same system. The obtained results were as follows: 1. Group A, B, and C did not show significant differences each other in the muscle activity of resting position in most of head and neck muscles. 2. Group B showed significantly lower muscle activity in maximum clenching than group C in anterior temporal(p<0.01), masseter(p<0.05), SCM(p<0.05) and digastric muscles(p<0.05). 3. Group A showed significantly lower muscle activity during swallowing than group C in anterior temporal and masseter muscles(p<0.01). Group B showed significantly lower muscle activity during swallowing than group C in anterior temporal(p<0.01), masseter(p<0.01), and SCM muscles(p<0.05). 4. Group A and B showed increased positional change of the mandible during swallowing measured from vertical, anteroposterior and lateral aspects, and prolonged swallowing(p<0.05). 5. After given instructions for normal swallowing pattern, group A and B showed increased muscle activity during swallowing in anterior temporal, masseter and SCM muscles(p<0.01). Positional change of the mandible and time elapsed for swallowing also decreased after the instruction(p<0.01). 6. Occlusal splint did not change the muscle activity during swallowing. However, vertical change(p<0.01) and swallowing time(p<0.05) were decreased with splint.

• Journal of Oral Medicine and Pain
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• v.45 no.3
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• pp.49-55
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• 2020

Purpose: This study investigated the association between the objective indicator of masticatory function assessment and the masseter muscle thickness (MMT) using ultrasound imaging. Methods: A total of 99 subjects (males: 24, females: 75, mean age: 76) were analyzed. The maximum bite force (MBF) was measured with a pressure-sensitive sheet and an image scanner. The mixing ability index (MAI) was calculated by image analysis after asking the subjects to chew a wax specimen. The MMT during rest and clenching were obtained with a diagnostic ultrasound system, and the difference in MMT during rest and MMT during clenching was defined as the difference in masseter muscle thickness (DMMT). Multiple regression analysis was performed to determine the independent variables affecting MBF and MAI. Results: The MBF showed correlation with the number of remaining teeth (β=0.346, p=0.002) and DMMT (β=0.251, p=0.011). The MAI correlated with only the number of remaining teeth (β=0.476, p<0.001). Conclusions: The DMMT reflects the state of masseter muscle contraction, and can be used as a predictor as well as the number of teeth when assessing masticatory function.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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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.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.269-281
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• 1995

To study the characteristics of EMG power spectrum of masticatory muscles during sustained isometric contraction and recovery at various contraction times, the author analysed the EMG signals of anterior temporal and masseter muscles before, during, and after sustained isometric contraction at 50% level of maximum voluntary contraction (MVC) for 15,30,60 seconds. Twelve normal subjects were included in this study. The author came to following conclusions from the results. 1. MMF of anterior temporal muscle in the contraction period was significantly higher than that of masseter muscle during sustained isometric contraction regardless of isometric contraction times (p<0.05). 2. MMF in the contraction period decreased as the contraction time increased during sustained isometric contraction in both temporal and masseter muscles(p<0.05). 3. SMF in the contraction period increased as the contraction tie increased during sustained isometric contraction in both temporal and masseter muscles(p<0.01). 4. MMF in the first part of recovery period (20 seconds) decreased as the contraction time increased during sustained isometric contraction(p<0.05). However, MMF in the later parts of recovery period (20-120 seconds) showed no significant differences. 5. MMF of anterior temporl muscle in the recovery period was significantly higher than that of masseter muscle after sustained isometric contraction regardless of isometric contraction times (p<0.05). 6. The recovery rate of MF reached 100% in 100 seconds after the isometric contraction regardless of isometric contraction times.

• Archives of Plastic Surgery
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• v.32 no.3
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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.

• Journal of Oral Medicine and Pain
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• v.26 no.4
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• pp.355-367
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• 2001

치의학 분야에서 디지탈 근적외선 체열측정 장치(digital infrared thermographic imaging; DITI)의 응용이 미미한 것은 과거 열측정장치의 기술력이 부족한 것이 주된 요인이었다. 그러나 최근들어 기술이 진보함에 따라 실시간 열영상을 재현할 수 있게 되었고 이는 치의학 및 의학계에 많은 관심을 일으키고 있다. 지금까지의 연구를 보면 두개하악장애시 구강영역의 온도변화의 임상적 효용 가능성을 제시하였으나 안면 및 두경부에 대한 실제 기기 및 측정방법의 신뢰도에 대한 연구는 이루어지지 못한 상태이다. 본 연구에서는 DITI에 대한 신뢰도를 조사하였다. DITI의 모니터 상에서 비활동성 발통점의 부위를 찾아내기가 쉽지 않다. 따라서 모니터상에서 안면발통점(joint, temporalis anterior, masseter anterior, masseter inferior)의 부위를 찾아 온도를 찾아내는 방법과 미리 발통점 피부상에 링모양의 마크를 부착하여 모니터상에서 쉽게 찾아내는 방법을 사용하여 신뢰도를 조사하여 비교한 결과 다음과 같다. 1. 조사한 발통점 중에서 temporalis anterior, joint, masseter anterior과 masseter inferior의 순서로 피부온도가 유의하게 온도가 높았으나(p<0.05) masseter 내에서는 유의한 차이를 보여주지 않았다. 2. 4개의 발통점 모두에서 높은 열적 대칭성을 보였으며, 좌우 온도차이는 $0.1^{\circ}C$미만이었다. 3. 다른 시기에 조사한 조사자내 신뢰도는 두 조사자 모두 높은 상관관계를 보여주지 않았으며 대조군과 마크를 사용한 군간에는 뚜렷한 차이를 볼 수 없었다. 4. 동일한 시기에 조사한 조사자간 신뢰도는 두 시기 모두 joint 부위의 일부를 제외하고 높은 상관관계를 보여주었으며, 마크를 사용한 경우 사용하지 않은 경우 보다 훨씬 신뢰도가 높은 상관관계를 나타내었다. 이상의 결과로 보아 DITI는 두개하악장애환자에 대한 두경부 발통점의 온도변화를 측정하는 데 있어 시간에 따른 신뢰도는 결여되었으나 동일 시기의 측정에는 매우 유익할 것으로 사료되며, 특히 발통점에 대한 표시를 사용하는 경우 매우 정확한 온도를 조사할 수 있을 것으로 판단된다.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.560-571
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• 2002

Jaw relations and the recording methods have been controversial aspects of dentistry. The purpose of this study was to quantify the relative muscle activity of the masseter and temporal muscles in relation to different intermaxillary relations recorded by intra-oral tracer during maximal clenching and to decide the optimal mandibular position. Ten volunteers with healthy TMJ were studied. Intra-oral tracer was assembled and bite block was fabricated in the articulator. Intra-oral tracer was placed in the mouth, and four mandibular positions were recorded. EMG activity was recorded on a BIO-PAK system (Bio-Research Associates, Inc. USA.) in masseter and temporal muscle and compared in each mandibular positions. The results were as follows: 1. In comparison with maximum intercuspation, the chewing position was the most similar followed by tapping position, myocentric position and posterior border position. However the differences were not statistically significant. 2. In comparison of bilateral symmetry of masseter muscle, tapping position was the most symmetrical followed by chewing position and maximum intercuspation. Myocentric position and posterior border position were not symmetrical. (P<.05). 3. In comparison of bilateral symmetry of anterior temporal muscle, chewing position was the most symmetrical followed by posterior border position, maximum intercuspation, myocentric position and tapping position. However the differences were not statistically significant. 4. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on left side, posterior border position was the greatest followed by myocentric position, taping position, chewing position and maximum intercuspation. And the proportionality of posterior border position was greater than that of maximum intercuspation. (P<.05). 5. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on right side, myocentric position was the greatest followed by posterior border position, tapping position, maximum intercuspation and chewing position. However the differences were not statistically significant.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.5.1-5.8
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• 2018

Background: The objective of this study was to evaluate the influence of masticatory muscle injection of botulinum toxin type A (BTX-A) on the growth of the mandibular bone in vivo. Methods: Eleven Sprague-Dawley rats were used, and BTX-A (n = 6) or saline (n = 5) was injected at 13 days of age. All injections were given to the right masseter muscle, and the BTX-A dose was 0.5 units. All of the rats were euthanized at 60 days of age. The skulls of the rats were separated and fixed with 10% formalin for micro-computed tomography (micro-CT) analysis. Results: The anthropometric analysis found that the ramus heights and bigonial widths of the BTX-A-injected group were significantly smaller than those of the saline-injected group (P < 0.05), and the mandibular plane angle of the BTX-A-injected group was significantly greater than in the saline-injected group (P < 0.001). In the BTX-A-injected group, the ramus heights II and III and the mandibular plane angles I and II showed significant differences between the injected and non-injected sides (P < 0.05). The BTX-A-injected side of the mandible in the masseter group showed significantly lower mandibular bone growth compared with the non-injected side. Conclusion: BTX-A injection into the masseter muscle influences mandibular bone growth.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.149-158
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• 2021

Purpose : Forward head posture (FHP) is one of the most common postural malalignment of the cranio-cervical region. Previous studies have reported that FHP might affect both temporomandibular joint (TMJ) and cervical muscles, but still remains unclear. The purpose of this study was to compare the changes of craniovertebral angle (CVA) and muscle properties after smartphone use in healthy individuals with and without FHP. Methods : Fifteen healthy individuals aged 18 to 22 years were included. CVA was evaluated using Dartfish motion analysis, and the subjects were divided into two groups according to their CVA: a FHP group (n = 7, CVA less than 48 °) and a control group (n = 8, CVA more than 48 °). MyotonPro was used to measure muscle properties of masseter, digastric and sternocleidomastoid muscles (SCM). Each subject underwent 15-minutes of smartphone task (web browsing or video watching) in relaxed sitting posture. CVA and muscles properties were assessed both before and after the smartphone task. Results : There were significant changes in post measurements of CVA between the groups. Masseter muscle showed significant differences in pre and post measurements of all muscle properties, and digastric muscle showed significance only in muscle tone. Amount of changes (post-pre), however, showed no significant difference in this study. Conclusion : 15-minutes of smartphone task did not affect CVA and muscle properties of masseter, digastric and SCM in both groups, however, there were significant changes in pre and post measurements of CVA and some muscle properties of masseter and digastric muscles. Therefore, CVA, masseter and digastric muscles might be significantly changed in a heavy duration of smartphone usage more than 15-minutes. Further studies are needed regarding duration of smartphone task, assessments in other various TMJ muscle groups, and participants with pathological FHP conditions.