• Journal of Oral Medicine and Pain
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• v.15 no.1
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• pp.27-35
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• 1991

In order to evaluate muscular activity patterns of masticatory muscles and asymmetry patterns of muscular activity according to the levels of occlusal force, twenty-one individuals of age ranged from 23 to 27 years were examined. They were selected according to the following criteria : 1) no symptoms of temporomandibular disorder, 2) complete dentition except third molars, 3) normal or Angle's class I molar relationship and 4) no experience of dental treatment. The electromyographic amplitudes was measured for evaluation of muscular activity and asymmetric patterns of masseter and anterior temporal muscle during unilateral clenching at the levels of 10%, 20%, 40% and 50% of the maximum occlusal force by use of electromyogram and bite force meter. The obtained results were as follows : 1. The muscle activity indices of masticatory muscles of clenching side at the clenching levels of 10%, 20% and 30% of the maximum occlusal force were -19.12, -9.87, -0.49%, so that activity of anterior temporal muscle was dominant than that of masseter muscle. At the levels of 40%, 50% of the maximum occlusal force, muscle activity indices were 4.68%, 6.70%, so that activity of masseter was dominant at all level and as the levels of occlusal force was increased, muscular activity index was tend to decrease. 2. In masseter, asymmetry indices of muscular activity at the levels of 10%, 20% of maximum occlusal force were -10.34 and -1.24%, so that muscular activity of non-clenching side were dominant and at the levels of 30%, 40% and 50% each of maximum occlusal force, muscular activity was dominant on clenching side as 4.68, 7.18 and 10.9%. In anterior temporal muscle, asymmetry indices were 33.38%, 25.46, 2095, 10.23 and 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching side was dominant than that of non-clenching side at all levels, but as the levels of occlusal force was increased, asymmetry indices of muscular activity was tend to decrease. 3. Between both sides, average electromyographic amplitudes of masseter and anterior temporal muscle were correlated, so that as the levels of occlusal force was increased, average electromyographic amplitudes of both side in same muscle were increased proportionally. But asymmetry indices between muscular activities of masseter and anterior temporal muscle were not correlated.

• Journal of Oral Medicine and Pain
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• v.38 no.2
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• pp.143-147
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• 2013

Mouth opening limitation is generally caused by masticatory muscle or temporomandibular joint pain, disc dislocation without reduction, adhesion or ankylosis of the temporomandibular joint, and muscle contracture. But otorhinolaryngologic disease, neurologic and vascular disease, tumor, inflammation and infection may cause pain and mouth opening limitation which mimics temporomandibular disorders. Re-evaluation for possibilities of inflammation, infection and tumor should be in cases that do not show symptom improvement or appear with continuous aggravation despite of proper treatment. In this case, we report of medial pterygoid muscle pain and mouth opening limitation caused by periapical abscess of third molar spread to the pterygomandibular space.

• Journal of Oral Medicine and Pain
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• v.20 no.1
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• pp.171-183
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• 1995

This study was carried out to investigate the relationship between tensed mandibular positions, muscle tenderness and EMG activity, respectively, and between range of motion of the neck and sternocleidomastoid muscle tenderness. Under stressful conditions, most of people take several types of behavioral patterns. Two of them observed frequently are clenching of teeth and grasping of fist. Prolonged clenching or grasping should increase electromyographic activity of associated muscle, especially muscles of mastication and neck muscles and will cause hyperfunction, dysfunction and muscle pain. So it is necessary to relate EMG activity with muscle pain. The author performed routine clinical examination in 47 patients with Temporomandibular Disorders, especially for presence or absence of muscle tenderness. Mandibular rest position was used as a baseline reference position and two more position in which EMG activity was taken were rest postion with grasping of fist and teeth clenching position. BioEMG of Biopak system (Bioresearch Inc, USA) was used for measuring of integrated EMG in masseter, anterior temporalis, anterior belly of digastic muscle and sternocleidomastoid muscle. To measure of the range of neck motion. CROM(Cervical-Range-of Motion, USA) was used. The obtained results were as follows : 1. EMG activity of all muscles except in masseter was higher in grasping of fist than those in rest position and there were significant correlation in EMG activity between the two position except in anterior belly of digastric muscle. 2. When comparing EMG activity between tender and non-tender muscle, all examined muscles did not show any significant difference. From this data, we could conclude that EMG activity was generally not changed with tenderness, of couse, it might be dependent with degree of muscle tenderness. 3. Number of tender points in examined muscles was also not significantly different between in patients with masticatory muscle disorders and in patients with internal derangement. 4. Cervical posture and range of motion of the neck was not differed significantly between in patients with and in patients without tenderness of sternocleidomastoid muscle.

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.265-277
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• 1996

The aim of this study was to investigate the electromyographic(EMG) activity of masticatory and cervical muscles according to chewing pattern in coronal plane during gum chewing. 70 patients with temporomandibular disorders and 30 dental students without any signs and symptoms of the disorders participated in this study. We measured the activity of masseter (MM), anterior temporalis(TA), sternocleidomastoideus(SCM) and trapezius muscle and recorded the chewing patterns using Biopak system synchronously. Chewing pattern was classified into S- or L-pattern by the midline opening path and short or long type by the lateral distance from midline. Obtained data were analyzed with SAS/STAT Program. The obtained results were as follows : 1. Generally, there was tended to be higher activity in the control group than in the patients group. 2. When comparing EMG activity according to preferred side, the muscle activity was tended to higher on the preferred chewing side than on the contralateral side. However, this difference is insignificant statistically 3. In unilateral affected patients, there was no difference in muscle activity between affected chewing side and unaffected chewing side except for the EMG of the temporalis anterior muscle. 4. Despite the varietal in each of the following variables, there mere no differences in EMG activity during gum chewing: chewing pattern in coronal plane and lateral distance of chewing. 5. The activity of SCM in chewing side was higher than that in contralateral side (p<0.001), but there was no difference in trapezius muscle. 6. In all of the control group, there was appeared L-chewing pattern than not involved the midline during preferred side chewing.

• The Journal of the Korean dental association
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• v.38 no.6 s.373
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• pp.549-557
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• 2000

ㆍPurpose: This study was performed to investigate the initial conservative treatment for TMD patients using careful counselling and medication prospectively. ㆍMaterials and Methods: Careful counselling and medication were performed in 51 TMD patients and 27 patients had follow-up check 2 months or more. Diagnosis of TMD was based on medical history and, physical and radiographic examination. TMD included masticatory disorder, internal derangement, degenerative joint disease, inflammatory joint disorder. and problems resulting from extrinsic trauma. All patients had chief complaints of TMJ pain, mouth-opening limitation. joint noise, and/or referred pain. We counselled and explained to the patient about the pathogenesis, etiologic factors, diagnosis and treatment plan for abut 10 minutes. We prescribed nonsteroidal anti-inflammatorv analgesic(Somalgen) and amitriptyline 10mg per day for 2 weeks. We informed the patient of the attention sheet and taught self-exercise of jaw. The patient were assessed by answering the questionnaire of subjective evaluation of TMD & maxillofacial pain. Questionnaire of an activity limitation. Questionnaire of a jaw function, and Questionnaire for the evaluation of TMD. ㆍResults: In questionnaire for the evaluation of TMD, 88.5% of 26 patients answered that the treatment was efficacious. 71.4% of 21 patients answered no problem in everyday life. There were significant differences between pretreatment and final follow-up in the evaluation of the subjective pain in the following sections: opening widely, chewing, resting, morning, masticatory muscle, and temporal portion(SAS program, paired T-test, P = 0.05). ㆍConclusions: Considerate counselling and proper medication could be significantly effectve in the initial treatment of TMD.

• Journal of Oral Medicine and Pain
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• v.35 no.1
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• pp.49-59
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• 2010

The purpose of this study was to investigate short-term masticatory muscle reactions in response to simulated noise and music sound. Hypothesis of this study was that loud noise would cause increased stiffness and decreased elasticity of the masticatory muscles compared to low level of noise or identical sound level of music. Fifteen male volunteers were recruited for the study. The sound levels of noise and music used here were 60 dB and 100 dB. The experiment comprised 4 sessions, Session 1 with 100 dB of noise for the 1st day of experiment: Session 2 with 100 dB of music for the $2^{nd}$ day: Session 3 with 60 dB of noise for the $3^{rd}$ day: Session 4 with 60 dB of music for the $4^{th}$ day. Stiffness and elasticity on the anterior temporalis and superficial masseter muscles were measured with tactile sensor before and 2, 4 and 6 minutes after exposure of sound. The study indicated that, in short-term exposure of sound, there was no significant difference between noise and music at both 60 and 100 dB of sound level, but that there were partially significant differences between 60 and 100 dB of sound level regardless of sound type. This suggest that high level of sounds like 100 dB used in this study, in spite of short term exposure of several minutes, would lead to masticatory muscle contraction, especially in the masseter muscles.

• Journal of Oral Medicine and Pain
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• v.45 no.4
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• pp.115-119
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• 2020

Infectious myositis, an infection of the skeletal muscles, is a rare condition and potentially life-threatening if not detected and treated in the early stages. This clinical entity may arise from various pathogens, such as bacteria, fungi, parasites, and viruses. A propagation of contiguous infection, penetrating trauma, vascular insufficiency, or hematogenous spreading of microorganisms can cause infectious myositis. Though several cases have been reported in large muscle groups in the lower extremities, there are only a few reports on infectious myositis of the masticatory muscles. We report three cases of infectious myositis presenting jaw pain and trismus. Unlike a common head and neck infection caused by the spreading of odontogenic origin, the early diagnosis of infectious myositis was difficult because no specific lesion suspected to be the infection source was observed in the physical examination and the plain radiographs. Advanced imaging modalities such as computed tomography and magnetic resonance imaging, and laboratory evaluation is useful for the early detection of infectious myositis.

• Journal of Oral Medicine and Pain
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• v.45 no.4
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• pp.110-114
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• 2020

Myofascial pain (MFP) is one of the most common causes of persistent orofacial pain. Patients with chronic myofascial orofacial pain may present with diffuse heterotopic pain, complicating the correct diagnosis. Treatment of chronic MFP should focus on the elimination of aetiologic factors. This article describes two cases of chronic MFP of the masticatory muscles, whose symptoms were exacerbated after masseteric nerve neurectomy. The patients had suffered from irrelevant treatment which did not resolve the symptom. Their symptom was managed by conventional treatment protocol. These cases emphasize the importance of correct diagnosis and evidence-based approach.

• 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.

• Journal of Oral Medicine and Pain
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• v.38 no.4
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• pp.325-331
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• 2013

Botulinum neurotoxin(BoNT) is a protease exotoxin produced from Clostridium botulinum. It works by blocking the release of acetylcholine from cholinergic nerve endings causing inactivity of muscles or glands. Recently, the therapeutic use of BoNT have expanded to include a wide range of medical and dental conditions. Botulinum neurotoxin type A(BoNT/A) is used off-label in the orofacial region to treat primary and secondary masticatory and facial muscle spasm, severe bruxism, facial tics, orofacial dyskinesias, dystonias, and hypertrophy of the masticatory muscles. Local hematoma, infection, and persistent pain in the injection site are the site-of-injection side effects. Medication-related side effects are adjacent muscle weakness, slurred speech, an alteration in the character of the saliva, and severe headaches. In most cases, these complications are not persistent and bothersome. We reported a case report of a patient who had transient anterior open bite after BoNT/A injection on masseter muscles to treat the refractory myofascial pain.