骨性Ⅲ类错(牙合)畸形患者正颌手术前后咀嚼肌功能变化的初步研究

目的:应用肌电图仪评价骨性Ⅲ类错(牙合)畸形患者正颌手术前后咀嚼肌功能的变化.方法:收集16例骨性Ⅲ类错(牙合)畸形需正颌手术病例和20例正常(牙合)和二腹肌前腹的表面募集电位,并计算其肌不对称指数运动.病例组在术后3个月和6个月时重复测定,采用t检验进行统计学分析,并与对照组进行比较.结果:手术前病例组咀嚼肌电位小于对照组,尤以紧咬和咀嚼时差异显著(P＜0.05),肌不对称指数与对照组无差异.术后3个月时,部分肌功能恢复,但紧咬和咀嚼时募集电位下降显著(P＜0.001),肌不对称指数也增大,提示此时肌功能尚未完全恢复.术后6个月各种功能运动时的募集电位均大于术前水平,肌不对称指数则基本小于术前水平,说明肌功能有所改善.结论:骨性Ⅲ类错(牙合)畸形患者手术前咀嚼肌功能弱于对照组,正颌手术矫正了颌骨位置和咬合关系,改善了患者的咀嚼肌功能.     

不同牙合型人群咀嚼肌肌电活动的研究

目的:利用肌电图仪测量不同牙合型人群咀嚼肌肌电活动,分析比较各组人群的咀嚼肌肌电特点和差异。方法:1)选取符合实验标准的自愿者33人,平均年龄21.71岁。分组,正常对照组10人,安氏Ⅰ类错牙合组10人,安氏Ⅱ类错牙合组8人,安氏Ⅲ类错牙合组5人;2)用肌电图仪测量各组人群的测量不同牙合型的咀嚼肌肌电活动;3)用SPSS17.0软件进行统计学分析,得出各组人群的咀嚼肌肌电特点和差异。结果:1)静息状态下,显著性>0.05,各组人群咀嚼肌的电位变化没有显著性差异;2)咀嚼过程中,安氏Ⅲ类错牙合畸形组,与正常对照组、安氏Ⅰ类错牙合畸形组、安氏Ⅱ类错牙合畸形组相比,咬肌的电位值显著性<0.05,存在显著性差异;3)吞咽时,①安氏Ⅱ类错牙合畸形组人群,与正常对照组间咬肌的电位比较,显著性<0.05,存在显著性差异;②安氏Ⅲ类错牙合畸形组人群,与正常对照组、安氏Ⅰ类错牙合畸形组咬肌的电位相比较,显著性<0.05,存在显著性差异;③安氏Ⅲ类错牙合畸形组与其余3组二腹肌电位相比较,显著性<0.05,存在显著性差异。4)不同状态时各组人群两侧咀嚼肌肌电变化不同,存在相关性与差异性。结论:不同牙合型人群在咀嚼和吞咽过程中,咀嚼肌肌电活动有所不同,推断错牙合畸形可影响咀嚼肌的正常功能运动。     

单侧后牙反(牙合)患者的咀嚼肌肌电图分析

目的: 通过对单侧后牙反(牙合)患者咀嚼肌肌电检查,分析单侧后牙反(牙合)对咀嚼功能的影响.方法:用肌电图仪记录20 例(男11 例,女 9 例)单侧后牙反(牙合)患者和20 例(男10 例,女10 例)正常对照组在下颌姿势位、紧咬和双侧咀嚼时咬肌和颞肌前束的肌电数据.计算咬肌的活动不对称指数(ASMM)和颞肌前束的活动不对称指数(ASTA),然后进行统计学分析.结果:在紧咬和双侧咀嚼时,单侧后牙反(牙合)组咬肌和颞肌前束肌电值明显低于对照组(P＜0.05),反(牙合)侧明显低于非反(牙合)侧;单侧后牙反(牙合)组与对照组ASMM和ASTA在紧咬和双侧咀嚼时有显著性差异(P＜0.05);单个后牙反(牙合)组与多个后牙反(牙合)组ASMM和ASTA在紧咬和双侧咀嚼时有显著性差异(P＜0.05).结论:单侧后牙反(牙合)对咀嚼肌功能有明显的影响,应对其进行积极治疗.     

儿童替牙期骨性AngleⅢ类错(牙合)咀嚼肌肌电研究

目的:研究儿童替牙期骨性AngleⅢ类错(牙合)与正常(牙合)的咀嚼肌肌电变化规律.方法:对20例替牙期AngleⅢ类骨性错(牙合)儿童及20名正常(牙合)儿童进行咀嚼肌肌电图检查,测量嚼肌深浅层和颞肌前后束在姿势位、牙尖交错咬合位、前伸运动边缘位、后退运动边缘位的肌电活动,所得数据进行统计学分析.结果:骨性安氏Ⅲ类错(牙合)姿势位嚼肌与颞肌的肌电活动均大于正常(牙合);牙尖交错咬合位嚼肌、颞肌肌电位均较正常(牙合)小;下颌前伸时颞肌前束肌电显著性高于正常(牙合);下颌后退时,嚼肌显著性高于正常(牙合).结论:替牙期AngleⅢ类骨性错(牙合)肌电有其特征性,提示早期矫治替牙期AngleⅢ类骨性错(牙合)不仅能解决美观问题,更有利于改善咀嚼肌收缩功能,减少肌功能对颅面形态的不良影响.     

骨性III类错畸形患者正颌手术前后力变化的初步研究

目的:应用计算机咬合分析系统,评价正颌手术前后骨性III类错牙合患者牙合力的变化。方法:收集15例骨性III类错牙合需正颌手术病例,利用T-ScanII牙合诊断分析系统在术前1周内、术后3个月和术后6个月时对患者的牙合力进行测定,分析患者的总牙合力(TOF)、MIP/MAX指数、牙合力不对称指数(AOF)、牙合力中心点位置(COF)及咀嚼时最大位移距离(MCOF),应用配对t检验进行比较研究。结果:术后3个月时TOF有所上升,6个月时与术前水平相比已有显著差异(P<0.05),说明患者牙合力水平已有提高。MIP/MAX指数略有下降,但6个月时增大并超过术前水平。AOF术后呈下降趋势,在3个月和6个月时均比术前显著减小(P<0.01,P<0.001)。术后COF逐渐接近正常,MCOF减小,术后6个月时均较术前明显改善,说明患者牙合力水平已有提高。结论:正颌正畸联合治疗能够改善骨性III类错牙合患者的牙合力水平及力平衡性。     

骨性III类错畸形患者正颌手术前后下颌运动轨迹变化的初步研究

目的:应用下颌运动轨迹仪评价骨性III类错牙合畸形患者正颌手术前后下颌运动的变化。方法:对15例骨性III类错牙合畸形需正颌手术病例和20例正常牙合对照组,采用ARCUSDigma下颌运动轨迹仪测定受试者最大开口运动,前伸及左右侧边缘运动距离,记录由计算机通过切牙运动模拟的双侧髁突的运动轨迹间的最大差数(MRC)。通过自身比较以及与对照组比较,评价患者在术前、术后3个月及6个月时下颌运动的变化以及髁突运动的对称性。采用团体t检验和配对t检验进行统计学处理。结果:术前患者除开口度外,其他运动距离均小于对照组,前伸运动差异显著(P<0.05);开口时MRC值大于对照组(P<0.05)。术后3个月时,开口度及左侧运动距离下降,前伸和右侧运动略有增加;MRC呈上升趋势。术后6个月时,下颌运动距离均有所增加,除开口度外其余均超过术前水平,与对照组无统计学差异;MRC小于术前水平且与对照组差异无显著性。结论:骨性III类错牙合畸形患者下颌运动水平与正常牙合存在差异,髁突运动对称性较差。正颌手术能够有效地改善患者的下颌运动功能。     

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     

正畸与正颌联合治疗成人骨性反(牙合)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:20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.     

Forsus矫治恒牙期安氏Ⅱ类错(牙合)下颌后缩的肌电图研究

目的 Forsus应用于已过生长发育高峰期安氏Ⅱ类错(牙合)下颌后缩恒牙期患者,观察比较治疗前后咬肌肌电图的变化规律,探讨肌功能平衡与骨组织改建的关系.方法 临床选择19例(男9例,女10例)青少年晚期安氏Ⅱ类错(牙合)下颌后缩患者,年龄在14～16.5岁,恒牙(牙合).治疗前后分别进行咬肌开颌反射、下颌姿势位咬肌肌电图、牙尖交错(牙合)紧咬咬肌募集肌电图、咬肌咀嚼周期肌电图的检测.应用SPSS12.0统计软件对治疗前后的测量结果进行配对t检验.结果 肌电图测定:①开(牙合)反射潜伏期无明显变化,静止期由原来延长趋于正常;②下颌姿势位图形稳定,无异常波形出现;③牙尖交错位紧咬由原来异常的混合相趋于正常的干扰相,图形密集,波幅增高,波形趋于一致;④咀嚼周期食物粉碎相异常停顿消失或减少,图形较一致,开口相、闭口相无异常收缩出现;⑤咀嚼周期总时程有缩短趋势.结论 应用Forsus矫治器治疗已过生长发育高峰期安氏Ⅱ类错(牙合)下颌后缩患者,引导下颌向前改变颌位后,影响咬肌功能发挥的周围条件发生改变,咬肌肌功能活动增强,肌电图规律趋于正常.     

替牙期骨性安氏Ⅲ类错(牙合)下颌运动时咬肌及颞肌前束的肌电分析

咀嚼肌群作为口颌系统中重要的动力部分,其形态和功能直接影响颌面的生长发育[1].咀嚼肌功能的强弱,不仅可以改变颅颌骨骼周缘的血运及机械力学环境,使局部骨质发生改建,而且可以控制骨缝骨质沉积,影响整个面部的生长型[2,3].本研究拟通过对替牙期骨性AngleⅢ类错(牙合)患者的咬肌和颞肌前束在下颌边缘运动中肌电活动变化的研究,观察此类错(牙合)畸形患者与正常组的咀嚼肌肌电活动差别,为错(牙合)畸形矫治和病因研究提供依据.     

Influence of Variation in Jaw Posture on Sternocleidomastoid and Trapezius Electromyographic Activity

This study was conducted in order to determine the influence of variation in the occlusal contacts on electromyographic (EMG) cervical activity in 20 patients with myogenic cranio-cervical-mandibular dysfunction. EMG recordings during maximal voluntary clenching were performed by placing surface electrodes on the left sternocleidomastoid and upper trapezius muscles in the following conditions: intercuspal position; edge to edge left laterotrusive contacts (ipsilateral); edge to edge right laterotrusive contacts (contralateral); edge to edge protrusive contacts; and retrusive occlusal contacts. A significant higher EMG activity was recorded in both muscles during maximal voluntary clenching in retrusive occlusal contact position, whereas no significant differences in EMG activity were observed between intercuspal position, ipsilateral, contralateral and protrusive contact positions. The EMG pattern observed suggests that a more frequent intensity and duration of tooth clenching in retrusive occlusal contact position could result in more clinical symptomatology in these cervical muscles in patients with myogenic cranio-cervical-mandibular dysfunction.     

Anterior temporalis and suprahyoid EMG activity during jaw clenching and tooth grinding

The aim of this study was to evaluate the anterior temporalis and suprahyoid electromyographic (EMG) activity during jaw clenching and tooth grinding at different jaw posture tasks. The study included 30 healthy subjects with natural dentition and bilateral molar support, incisive protrusive guidance and bilateral laterotrusive canine guidance. Bipolar surface electrodes were located on the right anterior temporalis and suprahyoid muscles. Three EMG recordings in the standing position were performed in the following tasks: C. clenching in the intercuspal position (IP); P1. eccentric grinding from IP to protrusive edge-to-edge contact position; P2. clenching in protrusive edge-to-edge contact position; P3. concentric grinding from protrusive edge-to-edge contact position to IP; L1. eccentric grinding from IP to laterotrusive edge-to-edge contact position; L2. clenching in laterotrusive edge-to-edge contact position; L3. concentric grinding from laterotrusive edge-to-edge contact position to IP. EMG activity during protrusive and laterotrusive tasks was lower than intercuspal position in the anterior temporalis, whereas an opposite EMG pattern was observed in the suprahyoid muscles activity, excepting recorded activity in L2 (mixed model with unstructured covariance matrix). Anterior temporalis activity was higher during P3 than P1 and P2 tasks and during L3 than L1 and L2 tasks, whereas in the suprahyoid muscles, activity was higher during P1 than P2 tasks and during L1 than L2 and L3 tasks. These results could support the idea of a differential modulation of the motor neuron pools of anterior temporalis and suprahyoid muscles of peripheral and/or central origin.     

Influence of surgical orthodontic treatment on masticatory function in skeletal Class III patients

Skeletal Class III patients exhibit malocclusion characterised by Angle Class III and anterior crossbite, and their occlusion shows total or partially lateral crossbite of the posterior teeth. Most patients exhibit lower bite force and muscle activity than non‐affected subjects. While orthognathic surgery may help improve masticatory function in these patients, its effects have not been fully elucidated. The aims of the study were to evaluate jaw movement and the electromyographic (EMG) activity of masticatory muscles before and after orthognathic treatment in skeletal Class III patients in comparison with control subjects with normal occlusion. Jaw movement variables and EMG data were recorded in 14 female patients with skeletal Class III malocclusion and 15 female controls with good occlusion. Significant changes in jaw movement, from a chopping to a grinding pattern, were observed after orthognathic treatment (closing angle P < 0·01; cycle width P < 0·01), rendering jaw movement in the patient group similar to that of the control group. However, the grinding pattern in the patient group was not as broad as that of controls. The activity indexes, indicating the relative contributions of the masseter and temporalis muscles (where a negative value corresponds to relatively more temporalis activity and vice versa) changed from negative to positive after treatment (P < 0·05), becoming similar to those of control subjects. Our findings suggest that orthognathic treatment in skeletal Class III patients improves the masticatory chewing pattern and muscle activity. However, the chewing pattern remains incomplete compared with controls.     

Masticatory muscle activity in myotonic dystrophy patients

summary The aim of the study was to compare the masticatory pattern and the activity of the masticatory muscles of a group of myotonic dystrophy patients with those of a group of healthy individuals. The electromyographic (EMG) activity of the temporal and the masseter muscles was measured in the resting position, during maximal clenching, and while the patient was chewing five peanuts until swallowing. It was found that the patients had approximately 3 times less EMG activity in the masticatory muscles during maximal clenching. During chewing the patients had approximately half the activity in the anterior temporal and the masseter muscles, while the activity of the posterior temporal muscle did not differ significantly from that in healthy individuals. No differences were found in the muscle activity in the resting position or in the speed of chewing between the groups. The patients needed more time and more chewing cycles to bring the five peanuts to the swallowing threshold, but possibly this was an effect of the lower number of antagonizing teeth. Myotonic dystrophy thus influences the masticatory muscles, reducing their activity both at a maximal and a functional level.     

Clenching and Grinding: Effect on Masseter and Sternocleidomastoid Electromyographic Activity in Healthy Subjects

Abstract

This study compares the effect of clenching and grinding on masseter and sternocleidomastoid electromyographic (EMG) activity during different jaw posture tasks in the sagittal plane. The study included 34 healthy subjects with natural dentition, Class I bilateral molar Angle relationship, and absence of posterior occlusal contacts during mandibular protrusion. An inclusion criterion was that subjects had to be free of signs and symptoms of any dysfunction of the masticatory system. Bipolar surface electrodes were located on the right masseter and sternocleidomastoid muscles. EMG activity was recorded while the subjects were in standing position, during the following jaw posture tasks: A. maximal clenching in the intercuspal position; B. grinding from intercuspal position to edge-to-edge protrusive contact position; C. maximal clenching in the edge-to-edge protrusive contact position; D. grinding from edge-to-edge protrusive contact position to intercuspal position; E. grinding from retrusive contact position to intercuspal position. EMG activities in tasks B, C, D, and E were significantly lower than in task A in both muscles (mixed model with unstructured covariance matrix). EMG activity among tasks B, C, D, and E did not show significant differences in both muscles, except between tasks D and E in the masseter muscle. A higher effect was observed on the masseter than on the sternocleidomastoid muscle to avoid excessive muscular activity during clenching and grinding. The EMG patterns observed could be of clinical importance in the presence of parafunctional habits, i.e., clenching and/or grinding.     

Pain in the sternocleidomastoid muscle and occlusal interferences

The EMG of the sternocleidomastoid muscle and the masticatory muscles during function has been observed in relation to opposing occlusal contacts. The purpose was to investigate the possible developmental mechanism of pain which can occur in the muscles. Six subjects with normal function and ten patients were studied. EMG activities of temporal, masseter, sternocleidomastoid (insertion) and sternocleidomastoid (middle) were recorded by surface and needle electrodes. EMG activity was recorded from the insertion of the sternocleidomastoid during activity of the masticatory muscles in tapping, clenching, and mastication. On the other hand little activity was registered from the middle of the sternocleidomastoid. The amplitude of the EMG of SCM-I increased as the occlusal force increased. During chewing the sternocleidomastoid muscle was functioning more actively on the working side than on the non-working side. On the patients, EMG activities of the muscles were of low amplitude and low frequency with no synchronization with the chewing movement, suggesting hyperactivity of the muscle.     

Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prostheses

OBJECTIVES: To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures. MATERIAL AND METHODS: Nineteen subjects aged 45-79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls. RESULTS: During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left-right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found. CONCLUSION: Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition.     

Changes in masticatory jaw movement and muscle activity following surgical orthodontic treatment of an adult skeletal Class III case

This case report examines the masticatory jaw movements and electromyograph (EMG) recordings of anterior and posterior temporal and masseter muscles before and after surgical orthodontic treatment in an adult patient with incisor crossbite and skeletal Class III jaw base relationship. The prescribed treatment resulted in a good occlusion and skeletal and dental Class I relationship. The chopping type jaw movement pattern during gum chewing was transformed to more of a grinding motion after treatment. But this motion was not as broad as is normally seen. This observation is indicative of the difficulties associated with improving the masticatory jaw movements in an adult patient to a completely normal pattern even after retention. In this patient, the high frequency of silent periods on the EMG that were observed in the early intercuspal phase before treatment were decreased to normal low levels after treatment. A similar decrease was also seen in the mean duration of the chewing cycle. We conjecture that this patient unsuccessfully attempted to compensate for the silent periods by increasing the period of his chewing cycle.