• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.115-122
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• 1993

This study was undertaken to compare the activity of masticatory muscle between normal occlusion and anterior openbite. 33 subjects without the experience of orthodontic treatment, missing teeth and the symptom of T. M. disorders were selected for this study : 25 subjects were normal occlusion and 8 subjects were anterior openbite. The ten items were measured from the cephalometric headplates, and EMG recordings of the anterior temporal and masseter muscle were taken at rest position and during maximum clenching at centric occlusion. All data were analyzed and processed with the computer statistical method. The following results were obtained : 1. At rest position, the muscle activities of both temporal and masseter muscle were higher in anterior openbite than in normal occlusion. 2. During maximum clenching, the muscle activities of both temporal and masseter muscle were prominently lower in anterior openbite than in normal occlusion. 3. At rest position, the temporal muscle of anterior openbite showed the highest muscle activity, but showed the lowest muscle activity during maximum clenching. 4. Anterior openbite showed closer interrelationship between facial morphology and the muscle activity, and the muscle activity was more influenced by the form of mandible than that of maxilla.

• Journal of Oral Medicine and Pain
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• v.48 no.4
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• pp.159-168
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• 2023

Purpose: Coordinated activity between the jaw and neck muscles is important in oral motor tasks such as chewing. This study examined coherence between the jaw and neck muscles during chewing in healthy adults. Methods: A total of 12 healthy adults underwent electromyography (EMG) of the jaw and neck muscles during right-sided chewing at a frequency of 1 Hz. Surface electrodes were placed over the temporalis (TA), masseter (MS), anterior digastric (DA), and sternocleidomastoid (SM) muscles on the right side. EMG signals were processed for coherence and phase analysis using advanced signal processing techniques. Results: The MS and TA muscle pair exhibited high synchronization when chewing (median coherence=0.992). Contrarily, the coherence values between the MS and DA, as well as the MS and SM muscle pairs, were relatively low (median coherence=0.848 and 0.957, respectively). Phase analysis revealed minimal temporal differences between the MS and TA muscle pair and the MS and SM muscle pair, whereas substantial phase shifts were observed between the MS and DA muscle pair. Conclusions: During chewing in healthy adults, the TA muscle works synergistically whereas the DA muscle antagonistically with the MS muscle, and the SM muscle supports the activity of the MS muscle. The observed synchrony and coordination provide insights into the intricate interplay among these muscles during oral motor tasks.

• Physical Therapy Korea
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• v.13 no.4
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• pp.39-46
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• 2006

The purpose of this study was to determine the effects of slump sitting postures on the masticatory, neck, shoulder, and trunk muscles associated with work-related musculoskeletal disorders (WRMD). Eleven healthy adults (age, $23.3{\pm}2.7$ yrs; height, $174.0{\pm}4.1$ cm; weight, $61.4{\pm}6.6$ kg) participated in this study. The participants were free of injury history and neurologic deficits in the masticatory, neck muscles and upper extremities at the time of participation. The subjects were asked to perform erect and slump sitting postures under the guidance of physical therapists. The surface electromyography (EMG) was recorded from the anterior temporalis, masseter, upper trapezius, serratus anterior, middle trapezius, L3 paraspinal, external abdominal oblique, gluteus maximus muscles of 11 adults as they performed visual terminal display work, which are known as the weakened and tightened muscles owing to WRMD. The recorded signals were averaged and normalized to the mean amplitude of the EMG signal obtained during submaximal reference voluntary contractions. The results of study were as follows: The masseter, upper trapezius, serratus anterior, middle trapezius, L3 paraspinal, external abdominal oblique muscles significantly differed in the slump sitting posture (p<.05). The muscle activities of the serratus anterior, middle trapezius muscle, and external abdominal oblique were significantly lower and that of the masseter, upper trapezius, L3 paraspinal muscles were significantly higher. Further research is needed to assess the motor control problems and the function of the deep muscles in posture stability of patients with WRMD.

• Journal of Oral Medicine and Pain
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• v.14 no.1
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• pp.113-121
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• 1989

In this study, 94 patients with temporomandibular disorders were interviewed to evaluate the effect of the treatment they received at the department of Oral diagnosis and oral Medicine in Seoul national university Hospital. The treatment administered to the patient were patient education, relaxation procedures, physical therapy, occlusal splint therapy and selective grinding of teeth. The following results were disclosed : 1. 97.9% of the patients reported no pain or considerably less pain than they had reported at their first visits to the department. 2. 89.3% of the patients thought that the treatment provided was either complete or considerably successful. 3. TMJ and facial pain was resolved within average 3.0 months 4. Of the 70 patients who previously reported having jaw joint sound, 34 patients (48.6%) no longer reported int. 5. Of the 48 patients who previously reported having headache regularly, 3 patients (68.8%) no longer reported headache regularly. 6. Of the 66 patients who previously reported having masticatory muscle pain, 41 patients (62.1%) no longer reported masticatory muscle pain. 7. Analysis of the data did not disclose a subgroup or factor, such as age, the stage of internal derangement, capsulitis, bruxism, MPD, duration of symptoms, that could be correlated with the reduction of pain or the patient's perception of success of treatment.

• 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 the Korean Academy of Esthetic Dentistry
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• v.31 no.1
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• pp.26-35
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• 2022

Patients who miss teeth partially or fully show many changes which make them lose function and esthetics.From the esthetic point of view, loosing teeth makes lower face unharmonized. There are various changes of lower and whole face according as how much change oral cavity is. Restoring the multiple teeth missing properly can make patient's face harmonized. Especially full mouth implant restorations can cause drastic occlusal change affecting masticatory muscles. Because all the muscles are connected closely, the masticatory muscles which is part of lower facial muscles can cause whole muscle change. In full mouth implant restoration case, I will show the whole face muscle change harmonized by meticulous occlusal treatment process. Full mouth restorations installed in right way show whole face muscle changes extending to head and neck muscles.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.421-429
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• 2007

Some researchers suggested that tactile sensor system would be useful in evaluating masticatory muscles of TMD patients, but there were few studies on the effects of chewing with time. The aim of this study was to investigate the change of elasticity and stiffness for masseter and temporal muscles of normal subjects before, during and after gum chewing and to obtain the baseline data for further researches on the elasticity and stiffness for masticatory muscles of TMD patients. Stiffness and elasticity of their anterior temporalis and inferior masseter muscle were measured bilaterally by a tactile sensor system. Each subject was instructed to sit on a chair for evaluation of masticatory muscles. Before operating the sensor, the thickest skin area over anterior temporalis and inferior masseter muscles were selected as the points to be pressed by a tactile sensor, and marked with a pen. While the teeth of subjects were lightly contacted, the probe of the tactile sensor was placed perpendicularly over the marked point over the skin, followed by computer-controlled movement including gently pressing straight down on the muscle for a second and retracting. All subjects were instructed to chew gum (Excellent Breath, Taiyo Co., Japan) bilaterally with a velocity of 2 times per second for 40 minutes after the first measurement had been performed for the baseline data of all subjects. The measurements had been repeated during chewing with 10 minutes of interval and continued for 40 minutes with same interval after chewing. Resultantly, the decrease of elasticity and the increase of stiffness in masticatory muscles can be seen significantly within 10 minutes after chewing and those were maintained during chewing without significant change with chewing time. The elasticity of muscles was recovered within 10 minutes after stopping chewing, but the stiffness was recovered more lately than elasticity by about 10 minutes. Based on these results, it can be concluded that elasticity and stiffness of muscles would be good indicators to evaluate the masticatory muscles objectively, when more supported by further researches.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.355-373
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• 1995

Craniofacial region is a musculodentoskeletal system that consists of many anatomical structures ; cranioskeletal structures, dental arches, and formation and functions of masticatory muscles have close correlations. Growth and development of craniofacial region are influenced by not only hereditory factors, but also environmental factors such as craniofacial muscles and surrounding tissues. On the contrary, however, study on changes in functions or adaptations of craniofacial muscles following changes of craniofacial skeletal structures has been somewhat insufficient. The author's purpose was to observe correlations between masticatory muscular functions and change patterns according to cranial skeletal structures and occlusion patterns, for this, comparative study of muscle activity changes of preand post- orthognathic surgery states in skeletal Cl III malocclusion patients was peformed. The selected sample groups were 15 normal male patients, 15 skeletal Cl III pre-orthognatic surgery patients and 15 skeletal Cl III post-orthognatic surgery patients. For each sample groups, cephalometric x-ray taking, masticatory efficiency test and measurements of muscle activities in anterior temporal muscle, masseter and upper lip in rest, clenching, chewing and swallowing were carried out. The following results were obtained : 1. In resting state of mandible, pre-surgery malocclusion group showed higher m. activities in ant. temporalis, masseter and upper lip than post-surgery group. Post-surg. malocc. group showed significantly high m. activity only in upper lip compared to the normal group. 2. In clenching state, post-surg. malocc. group showed higher m. activities in ut. temporalis, masseter and upper lip than pre-surg. malocc. group. 3. In chewing state, post-surg. malocc. group showed higher m. activities in ant. temporalis and masseter than pre-surg. malocc. group, on the other hand, decreased upper lip activity was noticed. 4. In swallowing state, post-surg. malocc. group showed lower upper lip activity than pre-surg. malocc. group but higher than that of the normal group. No significant difference in m. activities of ant, temporalis and masseter was noticed among the three groups. 5. Masticatory efficiency was lower in pre-surg. malocc. group than normal group, masticatory efficiency showed an increase in post-surg. malocc. group compared to the pre-surg. malocc. group. However, both groups showed significant differences compared to the normal group.

• Journal of Oral Medicine and Pain
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• v.38 no.2
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• pp.161-174
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• 2013

This study was designed to evaluate the pain control effect by morphine injection to masticatory muscle pain patients. Patients with masticatory muscle pain visited the Department of Oral Medicine, Kyung Hee University Dental Hospital were recruited to this study and diagnosed by RDC/TMD. Experimental group were divided into four group; saline injection group (n=10), lidocaine injection group (n=10), morphine 1.5 mg injection group (n=10) and morphine 3 mg injection group (n=10). Evaluation list was the subjective pain evaluation(visual analogue scale, Mc Gill pain questionnaire, pain drawing) and the objective pain evaluation(pressure pain threshold, pressure pain tolerance) and evaluation time was injection before, after 1 hour, 24 hour, 48 hour and then it was analyzed statistically. The results were as follows : 1. The subjective pain evaluation were significantly different statistically in morphine 3 mg group after 48 hour. (VAS: p<0.01, MGQ: p<0.001, PD: p<0.05) 2. The objective pain evaluation were significantly different statistically in morphine 1.5 mg group after 1 hour. (PPT: p<0.01, PPTol: p<0.05) 3. The morphine 3 mg group were more significantly different than lidocaine group and morphine 1.5 mg group statistically in the McGill pain questionnaire evaluation. (1h: p<0.01, 24h: p<0.01, 48h: p<0.001) Therefore, it was revealed that the morphine 3 mg injection was effective to pain control for masticatory muscle pain patients within 48 hours and more effect than lidocaine injection.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.146-153
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• 1992

In the outpatient clinic, we have many patients who suffer from temporomandibular joint disorders. These vary from MPD syndrome to osteoarthrosis, and many cases have tender spots or areas on the temporomandibular joint region and/or masticatory muscles. Further, they frequently have masticatory muscle pain when opening the jaw. This paper presents the results of our research on the differential diagnosis for tendernesses and pain on opening the jaw in the temporomandibular joint region and the masticatory muscles by joint cavity pumping with local anesthestic. The areas of tenderness and jae-opening paw in 65 patient suffering from temporomandibular joint disorder were examined and recorded before and after anesthetizing the upper joint cavity with 2% lidocaine. Maximum interincisal distance was similarly recorded. The results were as follows : In the area surrounding the upper joint cavity including the lateral pterygoid muscle, the tenderness and jaw-opening pain vanished almost entirely after anesthesia. This was considered a direct infiltrative effect of the local anesthesia. After the anesthesia, 86% of the tendernesses on the sternocleidomastoid muscles, and 66% of those on the posterior belly of the diagstric muscles vanished, while the disappearance rates on the masseter, temporal, and medial pterygoid muscles were 50~60%. Apart from the temporomandibular region, pain on opening the jaw was found on the masseter, temporal, posterior belly of the digastric muscles, and medial pterygoid muscles before anesthesia. The disappearance rates after anesthesia were 90~100% except for the pain of the posterior belly of the digastric muscles, for which the rate was 66%. These results suggest that more than 88% of the tendernesses on the sternocleidomastoid muscle, more than 60% of the tendernesses and jaw-opening pains on the digastric muscle, and more than half of the tendernesses and almost all of the jaw-opening pains in the jaw-closing muscles are referred pains from the temporomandibular joint. The tendernesses that had no change after anesthesia were considered to be derived from spasms of the muscles proper. Generally, maximum interincisal distance increased after anesthesia. The average distance was 34mm before anesthesia, but increased to 41mm after anesthesia. In a few cases, however little or no change was found in those distances. In these cases, pathological changes were found in the joint cavities arthrographically or arthroscopically.