• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.89-101
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• 1996

This study was performed to investigate influence of the changes of head posture on resting electromyographic (EMG) activity in anterior temporalis, masseter, sternocleidomastoid muscle and trapezius, and on status of occlusal contacts. For this study twenty-nine patients with temporomandibular disorders(TMD) and thirty dental students without any masticatory symptoms were selected as patients group and control group, respectively. EMG activity($\mu$V) at rest was observed in four kind of head postures such as natural or normal head posture(NHP), forward head posture(FHP), upward head posture(UHP), downward head posture(DHP), and in NHP and FHP, EMG activity with flat occlusal splint was also checked. BioEMG$^\textregistered$(Bioelectromyograph, Bioresearch Inc., USA) was used to record EMG activity in the above four muscles with eight locations on both sides. The author used T-Scan$^\textregistered$(Tekscan Co., USA) system to investigate the changes of oclusal contats on clenching in the four head postures about number, force, time(duration) and total left-right statistis(TLR, occlusal stability crossing left-right dental arch on clenching). For taking in upward or downward head posture, head was inclined $10^{\circ}$ upward or downward and CROM$^\textregistered$ (cervical-range-of motion, Performance attainment Inc., USA) was used to maintain same posture during the procedure. The results obtained were as follows : 1. For resting EMG activity, anterior temporalis did not show any difference by change of head posture, but masseter and sternocleidomastoid muscle showed higher value of EMG activity in FHP and UHP, and trapezius showed higher value of EMG activity in FHP and DHP. 2. EMG activity of trapezius was higher than that of any other muscles in NHP, FHP, and DHP, but in UHP, the activity was the lowest reversely. 3. Patients group showed higher EMG activity than control group did in all the muscles in NHP. And significant difference between the two groups were also observed in anterior temporalis in FHP, in sternocleidomastoid muscle in UHP, and in sterno-cleidomastoid muscle and trapezius in DHP with higher activity in patients group. 4. There was no change of EMG activity in NHp with splint, but EMG activity in anterior temporalis and masseter was decreased in FHP with splint. 5. In general, status of occlusal contacts was not changed with head posture in all subjects, and difference between patients group and control group was only noted for number and force of tooth contact in UHP and DHP with more value in control group. 6. Correlationship between EMG activity and number ad force of tooth contacts was shown negatively with regard to masseter in NHP, and trapezius in UHP and DHP.

• Journal of Oral Medicine and Pain
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• v.18 no.1
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• pp.9-19
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• 1993

The purpose of this study was to evaluate the effect of craniocervical posture on craniomandibular disorders with chronic headache. The author measured craniocervical posture on frontal and sagittal plane with photographs for 26 headache patients, 23 TMD patients, and 27 nonpatients. Range of cervical spine motion was also measured. The bilateral electromyograms of masseter and anterior temporalis muscles were recorded at rest and during maximum clenching. The results were as follows : On the lateral view photos, eye-tragus-C7 line angle was larger and the tragus-C7-horizontal line angle was smaller in the patient groups than in the nonpatient group (p<0.05). On the frontal view photos, mouth corner line angle was larger in the headache patient group than in the nonpatient group and TMD patient group (p<0.05) Interclavicular angle was smaller in the headache patient group and TMD patient grop than in the nonpatient (p<0.01) The right and left differences of SAIC-plane distance and finger tip-plane distance were significantly larger in headache patient group than TMD patient group and nonpatient group (p<0.01, p<0.001). Cervical motion range was smaller in the TMD patient group and headache patient group than in the nonpatient group (p<-.001, p<0.05, p<0.05). The resting EMG activities of right masseter muscle were higher in the headache patient group than in the nonpatient group (p<0.05). However, the EMG activities of masseter and anterior temporalis muscles during maximal clenching were lower in the patient group than in the nonpatient grop (p<0.01). The asymmetry index of resting EMG of masseter muscles was higher in the headache patient group than nonpatient group (p<0.05).

• The Journal of Korean Physical Therapy
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• v.34 no.6
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• pp.321-325
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• 2022

Purpose: Temporomandibular disorder (TMD) is a condition defined as pain and dysfunction of temporomandibular joints and masticatory muscles. Abnormal interconnections between temporomandibular muscles and cervical spine structures can cause the changes of postural alignment and balance ability. The aim of this study was to investigate changes in static balance ability in subjects with painrelated TMD. Methods: This study conducted on 25 subjects with TMD and 25 control subjects with no TMD. Pressure pain thresholds (PPTs) of the masseter and temporalis muscles were measured using a pressure algometer. Static balance ability was assessed during one leg standing using an Inertial Measurement Unit (IMU) sensor. During balance task, the IMU sensors measured motion and transfer movement data for center of mass (COM) motion, ankle sway and hip sway. Results: PPTs of masseter and temporalis muscles were significantly lower in the TMD group than in the control group (p<0.05). One leg standing, hip sway, and COM sway results were significantly greater in the TMD group (p<0.05), but ankle sways were not different between group. Conclusion: We suggest pain-related TMD is positively related to reduced PPTs of masticatory muscles and to static balance ability. These results should be considered together with global body posture when evaluating or treating pain-related TMD.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.183-192
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• 1997

Pressure pain thresholds are routinely used in orofacial pain research to evaluate the response of deep orofacial tissues to mechanical stimulation. Like other psychophysical measurements, however, this technique must stimulate cutaneous tissues before stimulating deeper tissues. This study aimed at evaluating the influence of the cutaneous hypoesthesia on the pressure pain threshold in 30 healthy volunteers. PPTs were determined with electric pressure algometry over masseter, temporalis anterior, sternocleidomastoid, and trapezius muscle before and after skin hypoesthesia. A local anesthetic cream and a control cream were applied following a placebo-controlled double-blind design and PPTs were reassessed. Two examiners measured PPTs two times on each muscles, randomly. And the EMG activity of all muscles were measured to evaluate the relationship with PPTs. The collected data were processed by SAS/STAT program. The obtained results were as follows : 1. There were a tendency to increase PPTs after than before cutaneous hypoesthesia, but, there were no significant difference statistically. 2. PPTs were consistently higher in anterior temporalis than in masseter muscle. 3. In all occasions, PPTs were higher in males than in females(p<0.001). 4. A statistically significant correlation was obtained from values of intra-examiners and inter-examiners in all measured muscles. 5. A significantly positive correlation was not found between PPT and functional EMG activity.

• Journal of Oral Medicine and Pain
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• v.39 no.4
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• pp.146-151
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• 2014

Purpose: To determine whether a fatiguing clench significantly affects the changes in pressure pain threshold (PPT) in men compared to women. Methods: The changes of PPTs from before to after a sustained clench in 12 men and 12 women were obtained. We used a decrease in median frequencies of surface electromyography (EMG) power spectra from the start to the end of the sustained clench as evidence of fatigue. Endurance time for the clench was used as a covariate. Results: The median frequencies decreased after the clench in both the anterior temporalis and masseter muscles, did not differ with the muscle or the gender of the subjects, and none of the interaction terms were significant. The PPTs were lower for women for both muscles, were decreased after the sustained clench, but failed to show the hypothesized gender by time interaction. Conclusions: Our results show that women have lower PPTs than men, but do not respond differently than men to jaw muscle fatigue.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.3
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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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• v.20 no.1
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• pp.97-103
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• 1995

The purpose of this study was to evaluate the effect of experimenter gender on pain report as well as the sex differences in pain threshold and pain tolerance. Cold pressor test and pressure pain threshold (PPT) test were performed on forty dental students by both of a male and a female experimenter separately with 1 day interval. The obtained results were as follows : There were no differences in pain threshold and pain tolerance between males and females when they were examined by the same gender experimenter in the cold pressor test, but when they were examined by the opposite gender experimenter the pain threshold of males was significantly higher than females. When the pain threshold was measured by the same gender experimenter, using a algometer, there was no differences in PPT between males and females. However, when the same measurements were done by the opposite gender experimenter, the PPT of males was significantly higher than females at anterior temporalis and inferior masseter. For cold pressor test, females tended to report lower levels of pain threshold and pain tolerance to a male experimenter than a female, but the differences were not significant. Although both pain threshold and pain tolerance were increased when males were examined by a female experimenter in the cold pressor test, the statistical significance was found only in pain tolerance. When subjects were examined by the opposite gender experimenter in the PPT text, females reported significantly higher levels of pain at inferior masseter and males reported significantly lower levels of pain at anterior temporalis and inferior masseter.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.137-143
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• 1997

두개하악장애는 가장 흔히 발병하는 질병중의 하나이다. 이때 저작계에 흔히 호소하는 주소가 근육의 통증이다. 통증의 정도를 측정하는 방법으로 촉진이 가장 널리 사용되고 있으나 정량화하기 어렵다는 단점이 있다. 따라서 통증 측정기 등과 같이 다양한 시도가 진행되고 있다. 근육이나 관절의 병적 소견은 해당조직의 혈액순환장애나 염증반응과 종종 관련이 있다. 이러한 상태는 신체의 표면과 밀접한 관계가 있어 피부온도에 영향을 미치며, 따라서 thermography로 측정할 수 있다. 피부온도의 측정은 질병의 활성 상태를 평가하는 데 유익하며, 또한 치료결과를 평가하는 데에도 효과적이다. 객관적 피부온도 측정장치가 있다면 턱관절이나 저작근의 이상상태를 평가하는데 매우 도움이 될 것이다. 따라서 본 연구의 목적은 경제적이면 양측성으로 특정 부위의 피부온도를 측정할 수 있는 기기를 사용하여 검사자내 및 검사자간 신뢰도를 측정하고 좌우 온도차이를 확인함으로써 향후 질환 및 치료 겨오가에 대한 임상적 평가시 객관적 측정방법의 하나가 될 수 있는 지를 알고자 하는 데 있다. 구강내 염증이나 이상이 없으며 두개하악장애가 없는 치과대학생 15명을 대상으로 조사하였다. 평균연령은 24.9세, 범위는 24-30세이었다. 사용한 기기는 미국산 YSI Precision 4000이다. 18-2$0^{\circ}C$의 일정한 실내온도에서 두 검사자가 각각의 검사를 알지 못하는 상태에서 별도로 정해진 부위에 검사를 시행하고, 약 1주일후 이전 검사에 대한 기억이 없어진 상태에서 두 검사자중 한 검사자가 다시 동일한 검사를 시행하였다. 측정치들을 이용하여 상관관계를 계산하고 이에 대한 유의성을 검정하였다. 1. 검사자내 상관관계(r)는 좌 .798(p=<.0001), 우 .757(p=<.0001)이었다. 2. 두검사자간 상관관계(r)는 좌 .958(p=<.0001), 우 .951(p=<.0001)이었다. 3. 좌우 측정치간의 차이는 유의한 차이가 없었다. 4. 근육부위별 측정에서는 inferior masseter muscle의 검사자간에서만 유의한 상관관계가 없었을 뿐 anterior masseter muscle, anterior temporalis 모두 검사자내 및 간에 유의한 상관관계를 나타내었다. 이상의 결과로 보아 정상인에 있어 근육내 발통점의 피부온도는 검사자간에는 특정부위에 따라 다소 차이가 있을 수 있으나 일반적으로 높은 재현성을 보여줌으로서 향후 교근 및 측두근의 임상연구 평가에 피부온도조사는 도움이 되리라 사료된다.

• 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.