Effects of breathing type on electromyographic activity of respiratory muscles at different body positions

Aim: To compare the effect of breathing type on the activity of respiratory muscles at different body positions.

Methodology: Two groups of 20 subjects each, one with upper costal and the other with costodiaphragmatic breathing, were studied. Electromyographic activity of sternocleidomastoid (SCM), diaphragm (DIA), external intercostal (EIC), and latissimus dorsi (LAT) muscles was recorded at standing and lateral decubitus positions during swallowing and maximal voluntary clenching.

Results: All muscles showed higher activity during standing in upper costal breathing subjects except the SCM muscle. EIC activity was higher during standing in the costodiaphragmatic breathing group. Subjects with upper costal breathing showed higher DIA activity than subjects with costodiaphragmatic breathing at both body positions and higher SCM activity at lateral decubitus position, whereas, EIC activity was only higher during swallowing.

Conclusions: Subjects with upper costal breathing presented higher respiratory effort than subjects with costodiaphragmatic breathing, being most prominent at the lateral decubitus position.     

Effect of breathing type on electromyographic activity of respiratory muscles during tooth clenching at different decubitus positions

Objective: To compare the effect of breathing type on electromyographic (EMG) activity of respiratory muscles during tooth clenching at different decubitus positions.

Methods: Forty young men participants were included, 11 with upper costal, 9 with mixed, and 20 with costo-diaphragmatic breathing type. EMG recordings of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM), and latissimus dorsi (LAT) muscles during tooth clenching in the intercuspal position were performed in dorsal, left lateral, and ventral decubitus positions.

Results: DIA EMG activity was higher in subjects with upper costal or mixed than with costodiaphragmatic breathing type (p = 0.006; 0.021, respectively), whereas it was similar between upper costal and mixed breathing types. EIC, SCM, and LAT activity was similar among breathing types.

Conclusion: Higher DIA activity would be a risk factor to exceed the adaptive capability of healthy subjects with upper costal or mixed breathing type.     

Effect of natural mediotrusive contact on electromyographic activity of jaw and cervical muscles during chewing

Abstract

Objective. This study evaluated the effect of a natural mediotrusive contact on the electromyographic (EMG) activity of the anterior temporalis and sternocleidomastoid muscles during chewing in healthy subjects. Materials and methods. The study sample included two groups of 15 subjects each (Group 1: with natural mediotrusive contact; Group 2: without natural mediotrusive contact). Bilateral surface EMG activity was recorded on anterior temporalis and sternocleidomastoid muscles during unilateral chewing of a half cookie and unilateral chewing of a piece of apple. Anterior temporalis and sternocleidomastoid muscle activity was normalized against activity recorded during maximal voluntary clenching in intercuspal position and maximal intentional isometric head–neck rotation to each side, respectively. The partial and total asymmetry indexes were also calculated. Data were analyzed using Mann-Whitney, Wilcoxon and unpaired t-test. Results. EMG activity of anterior temporalis and sternocleidomastoid muscles showed no significant difference between the groups. EMG activity of anterior temporalis was similar between working and non-working sides during chewing in both groups. EMG activity of sternocleidomastoid muscle was higher in the working side than in the non-working side in Group 2 subjects. Asymmetry indexes were not significantly different between groups. Conclusions. The similar EMG pattern and asymmetry indexes observed suggest the predominance of central nervous control over peripheral inputs on anterior temporalis and sternocleidomastoid motor neuron pools.     

Occlusal force, electromyographic activity of masticatory muscles and mandibular flexure of subjects with different facial types

Objective

The aim of this study was to evaluate whether vertical facial patterns influence maximal occlusal force (MOF), masticatory muscle electromyographic (EMG) activity, and medial mandibular flexure (MMF).

Material and Methods

Seventy-eight dentate subjects were divided into 3 groups by Ricketts''s analysis: brachyfacial, mesofacial and dolychofacial. Maximum occlusal force in the molar region was bilaterally measured with a force transducer. The electromyographic activities of the masseter and anterior temporal muscles were recorded during maximal voluntary clenching. Medial mandibular flexure was calculated by subtracting the intermolar distance of maximum opening or protrusion from the distance in the rest position. The data were analyzed using ANOVA followed by Tukey''s HSD test. The significance level was set at 5%.

Results

Data on maximum occlusal force showed that shorter faces had higher occlusal forces (P<0.0001). Brachyfacial subjects presented higher levels of masseter electromyographic activity and medial mandibular flexure, followed by the mesofacial and dolychofacial groups. Additionally, dolychofacial subjects showed significantly lower electromyographic temporalis activities (P<0.05).

Conclusion

Within the limitations of the study, it may be concluded that maximum occlusal force, masticatory muscle activity and medial mandibular flexure were influenced by the vertical facial pattern.     

正畸与正颌联合治疗成人骨性反后咀嚼肌肌电变化

目的 :检查对比分析成人骨性反牙合正畸与正颌手术联合矫治前后的主要咀嚼肌肌电 ,揭示正畸与正颌手术联合矫治后咀嚼肌功能的变化规律。方法 :2 0名正畸与正颌手术联合治疗的成人骨性反牙合患者 ,利用肌电图仪测试治疗前后咬肌、颞肌前束、二腹肌前腹在功能活动中肌电变化。结果 :正畸与正颌手术联合矫治对咬肌、颞肌前束、二腹肌前腹的功能活动均有不同程度的影响 ,其中对咬肌的功能影响最明显。结论 :正畸与正颌手术联合治疗成人骨性反牙合 ,咀嚼肌的异常肌张力多数得到纠正 ,但咀嚼肌的功能未能得到满意的恢复 ,咀嚼肌的功能恢复是一个复杂而长期的过程 ,还需要较长的功能锻炼恢复期     

实验性咬合高点诱发头面部疼痛时的肌电分析研究

目的:探讨咬合高点对咀嚼肌肌电活动的影响。方法:在10名个别正常牙合志愿者的右下第一磨牙上赋予牙尖交错位的咬合高点,赋予前以及赋予后第3天利用表面肌电图记录咬肌、颞肌前后束的肌电活动, 并用可视性疼痛示意尺记录受试者的头面颈部疼痛症状。采用秩和检验统计方法比较咬合高点赋予前后肌电活动的变化以及双侧肌电活动的不对称性变化,并进行疼痛症状和肌电活动变化之间的相关性分析。结果:赋予咬合高点后息止位右侧颞肌前束的肌电幅值和积分值显著增加;大力咬合时咬肌、颞肌前后束的肌电幅值和积分值明显减小,同时双侧颞肌前束的肌电活动不对称性指数显著增大(P<0. 05)。受试者出现了不同程度的口颌面痛症状,右侧颞部的疼痛程度与右侧颞肌前束息止位的肌电幅值以及积分值的增加倍数呈正相关(P=0. 001)。结论:赋予实验性咬合高点后干扰侧息止位颞肌前束的紧张度增加,大力咬合时双侧颞肌前束的肌电活动明显不对称,提示了肌电活动的变化与干扰侧颞部疼痛的发生有一定关系。     

正常骨面型儿童、成人上气道形态的X线头影测量分析

目的 比较正常骨面型儿童和成人的上气道形态,为不同年龄上气道正常参考值的建立和颅面部生长发育的研究提供一定的参考.方法 采用计算机辅助X线头影测量技术,对120名正常骨面型儿童、成人的X线头颅定位侧位片进行测量,并对上气道各水平测量值进行统计学分析.结果 儿童上气道各水平测量值无显著性别差异,成人上气道各段除喉咽段V-LPW外也无性别差异.从替牙期、恒牙早期到恒牙期,男性上气道PNS-R、PNS-AD2、V-LPW逐渐增大,而SPP-SPPW、U-MPW、TB-TPPW变化不显著,PNS-UPW从替牙期到恒牙早期变化显著,而从恒牙早期到恒牙期基本无变化;女性上气道PNS-R、PNS-AD2逐渐增大,而SPP-SPPW、U-MPW变化不显著,PNS-UPW、TB-TPPW、V-LPW从替牙期到恒牙早期变化显著,而从恒牙早期到恒牙期基本无变化.结论 儿童与成人的上气道形态具有一定差异,应该分年龄建立上气道正常参考值范围,为OSAS的诊断和治疗提供有力的依据.     

口呼吸与鼻呼吸儿童上气道矢状径差异的研究

目的 比较口呼吸与鼻呼吸儿童上气道矢状径的差异,探讨呼吸方式与上气道矢状径的关系。方法 通过口鼻气流同步测定系统的随机检测,选择鼻呼吸比例≤70％（口呼吸组）及≥95％（鼻呼吸组）的11－14岁儿童各34人,比较其头颅定位侧位片中上气道矢状径的差异。结果 口呼吸儿童骨性鼻咽（PNS－Ba）、舌咽部的最小距离（P－T）较鼻呼吸儿童明显减小。结论 鼻咽部骨性狭窄和扁桃体肥大是口呼吸的形态学原因,反映呼吸方式受遗传和环境两方面的影响。     

Effect of mouth breathing on masticatory muscle activity during chewing food

The aim of this study was to examine the effect of mouth breathing on masticatory muscle activity during chewing food. Masseter muscle activity during chewing of a rice ball was recorded in 45 adult volunteers (three women), identified as nose breathers. Surface electrodes were placed on the skin according to the orientation of the masseter muscle to record the activity of this muscle while the subjects chewed the food until swallowing. Each activity was recorded twice, once with nose breathing and once with mouth breathing induced by nasal obstruction. The integrated and mean electromyography values for mouth breathing were significantly lower than the values for nose breathing (P < 0·05). The resting and total duration of chewing were significantly prolonged (P < 0·05) and the active duration significantly shorter (P < 0·05) when breathing through the mouth compared with the nose. Significantly more chewing strokes were counted for mouth breathing compared with nose breathing (P < 0·05). Taken together, the results indicate that mouth breathing decreases chewing activity and reduces the vertical effect upon the posterior teeth.     

Effect of conventional TENS on pain and electromyographic activity of masticatory muscles in TMD patients

Temporomandibular disorders (TMD) are characterized by several signs and symptoms, such as pain and changes in the electrical activity of masticatory muscles. Considering that transcutaneous electrical nerve stimulation (TENS) is a resource indicated to promote analgesia, the objective of this study was to evaluate the effect of TENS on pain and electromyographic (EMG) activity of the jaw elevator muscles in TMD patients. This study evaluated 35 female volunteers: 19 TMD patients (mean age = 23.04 +/- 3.5) and 16 normal subjects (mean age = 23.3 +/- 3.0). Transcutaneous electrical nerve stimulation (conventional mode, 150 Hz) was applied once to each group for 45 minutes. Surface electromyography (gain of 100 times and 1 kHz sampling frequency) and the visual analogue scale (VAS) were applied before and immediately after TENS application. Both VAS data and root mean square (RMS) values were analyzed using Student's t-test. The TMD group, compared to the control group, showed higher EMG activity of the jaw elevator muscles at rest. No difference was observed between the groups regarding maximum voluntary clenching (MVC). In TMD patients, TENS reduced both pain and EMG activity of the anterior portion of the temporal muscle, increasing the activity of the masseter muscles during MVC. It is possible to conclude that a single TENS application is effective in pain reduction. However, it does not act homogeneously on the features of the electric activity of the muscles evaluated.     

Effect of unilateral posterior crossbite on the electromyographic activity of human masticatory muscles.

Studies dealing with the electromyographic activity of masticatory muscles in patients with unilateral posterior crossbite are infrequent. The purpose of this study was to assess the electromyographic pattern of masticatory muscles at rest position, during swallowing, and during mastication, in 30 subjects with right posterior crossbite and to compare them to 30 normocclusive subjects. The 2 groups were matched according to age, gender, skeletal Class I, and mesofacial growth pattern. Electromyographic activity of right and left anterior temporalis, posterior temporalis, masseter, and anterior digastric muscles was recorded at rest position, while swallowing water, and while chewing. Disposable bipolar surface electrodes were used in both groups. Data were compared between groups and between right and left sides within each group. The results revealed that the posterior temporalis of the non-crossbite side was more active than that of the same side in subjects with crossbite at rest position and during swallowing. The activity of both anterior digastrics was higher in the crossbite subjects during swallowing. During chewing the right masseter muscle was less active in the crossbite patients than in normocclusive subjects. The results obtained during chewing indicate a bilateral masticatory pattern in both groups.     

Effect of a prefabricated anterior bite stop on electromyographic activity of masticatory muscles.

STATEMENT OF PROBLEM: Patients are often treated for signs and symptoms in the masticatory musculature, which may be manifested as pain and/or conditions that cause difficulty in recording jaw relation records. A quick, easy method to alleviate these signs and symptoms would be helpful. PURPOSE: This study measured the effect of a prefabricated anterior bite stop on the electromyographic activity of the anterior temporalis, posterior temporalis, masseter and anterior digastric during clenching, and grinding tasks. MATERIAL AND METHODS: A prefabricated anterior bite stop was fabricated for 30 randomly selected subjects. Electromyographic surface electrodes were placed on the right and left sides of these muscles. Electromyographic activity was measured during clenching and grinding both with and without the anterior bite stop. RESULTS: The anterior bite stop had a significant effect in decreasing electromyographic activity for both clenching and grinding for all the tested muscles, except the anterior digastric. CONCLUSIONS: For this patient population, the ready-made anterior bite stop reduced electromyographic muscle activity for the anterior and posterior temporalis and the masseter muscles during both clenching and grinding.     

口呼吸与鼻呼吸儿童牙弓、基骨形态差异的研究

目的：比较口呼吸与鼻呼吸儿童牙弓、基骨形态的差异，探讨呼吸方式与牙弓、基骨形态的关系。方法：通过口鼻气流同步测定系统的随机检测，选择鼻呼吸比例≤70％(口呼吸组)及≥95％(鼻呼吸组)的11～14岁儿童各34人，测量石膏模型，比较其牙弓、基骨形态的差异。结果：①口呼吸儿童与鼻呼吸儿童相比腭盖较高，上颌基骨较窄，形态相对窄长。②口呼吸儿童比鼻呼吸儿童的上颌中、后段牙弓较长，牙弓形态相对窄长，下颌牙弓后段形态也相对窄长。结论：口呼吸可以引起儿童牙弓、基骨形态的改变。     

Effect of a nociceptive trigeminal inhibitory splint on electromyographic activity in jaw closing muscles during sleep

The nociceptive trigeminal inhibitory (NTI) splint has been claimed to decrease the electromyographic (EMG) activity of jaw-closing muscles and relieve symptoms of various types of temporomandibular disorders (TMD) and bruxism. The present study was designed to address the question about EMG-changes during sleep. Ten patients (age: 23-39 years) with a self-report of tooth-grinding during sleep were recruited. Patients were examined at baseline and after each treatment period with the use of the Research Diagnostic Criteria for TMD. A portable EMG-device was used to record EMG-activity from the masseter muscle during sleep. The patients received two 2-week splint treatments in a randomized cross-over fashion; an NTI splint and a standard flat occlusal splint (OS). EMG data were analysed according to published criteria. Using a 10% of maximum clenching EMG-activity cut-off threshold to determine the number of EMG-events h(-1) of sleep, the NTI splint was associated with a significant reduction (9.2 +/- 3.2 events h(-1)) compared with baseline EMG (19.3 +/- 4.0; anova: P = 0.004, Tukey post hoc: P = 0.006), whereas there were no differences between the OS (16.2 +/- 4.7) and baseline EMG (19.2 +/- 4.1; P = 0.716). There were no effects of either NTI or OS on clinical outcome measures (anovas: P > 0.194). This short-term study indicated a strong inhibitory effect on EMG-activity in jaw closing muscles during sleep of the NTI, but not the OS. However, the EMG-activity was not directly related to clinical outcome. Further studies will be needed to determine long-term effects and possible side effects of the NTI splint.     

健康人下颌运动时头颈肩部肌电活动的研究

目的　研究健康人的下颌息止位及运动时头颈肩部肌的协同活动。方法　用肌电积分值记录分析的方法调查 1 0名健康成人的下颌息止位和各种运动时颞肌前后腹、胸锁乳突肌和斜方肌的肌电活动。结果　无论在下颌息止位还是下颌运动中 ,胸锁乳突肌和斜方肌均有相应活动 ,胸锁乳突肌活动的增加倍数与颞肌前后腹活动的增加倍数有密切的正相关关系。斜方肌在不伴咬合的各种下颌运动时活动增加 ,而在大力咬牙和咀嚼时活动趋于停止。下颌不发生偏斜时 ,同一肌的左右两侧肌的活动有密切的正相关关系。结论　颞肌前后腹、胸锁乳突肌和斜方肌均参与维持下颌息止位及下颌运动。下颌功能和头颈肩部肌功能有密切关系     

不同垂直颅面结构年轻女性嚼肌超声厚度及肌电活动的相关性研究

目的:探讨不同垂直颅面结构的嚼肌超声厚度和肌电活动之间的关系.方法:根据SN-MP、FH-MP和FHI.将30名女大学生分为2组(高角14例、低角16例),应用B超测量姿势位和紧咬位的嚼肌厚度,表面电极测量姿势位和紧咬位的嚼肌肌电活动.采用SPSSI1.0软件包对数据进行分析,以独立样本t检验比较高、低角组间各项测量值的差异,Pearson相关分析评价嚼肌超声厚度和肌电活动之间的相关性.结果:低角组浅层嚼肌厚度在姿势位(P=0.009)和紧咬位(P=0.000)均大于高角组,具有显著性差异;在姿势位,低角组与高角组之间嚼肌肌电活动差异无统计学意义;在最大紧咬位,低角组的肌电活动显著大于高角组的肌电活动,差异有统计学意义(P=0.022);姿势位时,嚼肌厚度与最大紧咬位肌电活动呈正相关(低角组r=0.61,高角组r=0.38);紧咬位时,嚼肌厚度与最大紧咬位肌电活动也呈正相关(低角组r=0.73,高角组r=0.53).结论:不同垂直骨面型的嚼肌形态功能不同,低角骨面型的嚼肌超声厚度与肌电活动均大于高角组.     

Effects of endodontic instrument handle diameter on electromyographic activity of forearm and hand muscles

AIM: To determine the influence of the handle diameter of endodontic instruments on forearm and hand muscle activity using electromyographic (EMG) recording. METHODOLOGY: Size 45 K-type files were fitted with four different handle diameters; 3.5, 4.0, 5.0, and 6.0 mm. Seven dentists then attempted to negotiate to the working length acrylic resin root canals with each of the four handle sizes using a reaming motion. EMG activities were recorded from the flexor pollicis brevis muscle (f.p.b.), the flexor carpi radialis muscle (f.c.r.), and the brachioradialis muscle (b) with bipolar surface electrodes. The time taken to negotiate the canals, the area of integrated EMG that corresponded to the amount of EMG activity required during penetration and the maximum amplitude of EMG were measured using the EMG data. Results were analysed statistically using a one-way factorial ANOVA test and multiple comparison tests. RESULTS: Reaming time and integrated EMG area of each muscle decreased with an increase in handle diameter. The most significant difference in time and area of integrated EMG was detected between handles of 6 mm and 3.5 mm diameter (time: P < 0.01, area of the f.p.b.: P < 0.01, area of the f.c.r. and b: P < 0.05), and between handles of 5 mm and 3.5 mm diameter (P < 0.05). Both 5 mm and 6 mm handles significantly decreased the maximum amplitude of EMG recorded from the f.p.b. compared with 3.5 mm handles (between 3.5 mm and 6 mm: P < 0.01, between 3.5 mm and 5 mm: P < 0.05). CONCLUSION: The results indicate that handle diameter has an effect on reaming time as well as on muscle activity. As a consequence, handle diameter influenced operator performance during instrumentation.