Electromyographic and computer analyses of patients suffering from chronic myofascial pain-dysfunction syndrome: before and after treatment with immediate complete anterior guidance development.

Seven women patients at Tufts University School of Dental Medicine were evaluated for the subjective symptoms of a myofascial pain dysfunction. Each patient was evaluated by an occlusal analysis of the T-Scan computer to determine posterior disclusion time during excursive movements, and EMG analysis of the masseter and temporalis muscles. Each patient was then treated occlusally by developing immediate complete anterior guidance. This adjustment process involved the removal of all lateral and protrusive interferences prior to habitual closure adjustments. No attempt was made to retrude the mandible in centric relation, and splints were not used to deprogram the musculature before adjustment. In this study, protrusive movements and interferences were not examined, and there was no control group. Posttreatment EMG and T-Scan computer analyses revealed that by shortening disclusion times to less than 0.5 second in any lateral excursions, muscle function returned to normal in all seven patients in approximately 1 month's time. A direct correlation seemed to exist between contractile muscle activity and disclusion time. Lengthy disclusion time leads to excessive muscle activity that introduces spasm and fatigue of the masseter and temporal muscles. These results indicated that a partial explanation of the etiology of MPDS may be the time the molars and nonworking premolars remain in contact during excursive movements--a phenomenon termed "disclusion time."     

Reducing chronic masseter and temporalis muscular hyperactivity with computer-guided occlusal adjustments

Muscle hyperactivity is a potential source of symptomatology in patients with temporomandibular disorders. Various occlusal adjustment procedures have been advocated to reduce hyperactivity. A new, measurement-driven, occlusal adjustment procedure, known as immediate complete anterior guidance development (ICAGD), has been shown through nonsimultaneous electromyography to lessen masticatory muscle hyperactivity effectively by reducing posterior disclusion time to <0.4 sec in all mandibular excursions. This reduction, in turn, lessens the volume of periodontal ligament compressions that create additive and excessive functional muscle contractions via a feedback mechanism involving the trigeminal nerve. This case report describes the treatment of chronic muscular hyperactivity with a computer-guided ICAGD enameloplasty and simultaneously recorded electromyography. Follow-up visits showed that after reduction, the pretreatment levels of excursive muscular hyperactivity were lessened and lasting. This result is caused by the shorten ed posterior disclusio time resulting in an equally reduced time to muscle shutdown.     

Comparison of treatment options for myogenous temporomandibular dysfunction

A randomized clinical trial which included a follow-up of one year was applied to 118 myogenous TMD-patients. The therapies investigated were: physiotherapy of the masticatory system or splint therapy for patients without occlusal interferences, and occlusal adjustment therapy or the combination of splint and occlusal adjustment therapy for patients with pronounced occlusal interferences. Counseling, which yielded a reduction of 27% of the scored pain intensity, will most likely eliminate any further need for treatment of patients with a low level of myogenous TMD signs and symptoms. Otherwise, physiotherapy might be preferred as a starting option with respect to splint therapy because of 1. A similar efficacy; 2. A shorter treatment duration so that either chronic facial pain is earlier relieved or a patient can undergo a second type of therapy earlier; and 3. Lower costs. One third of the patients selected had pronounced occlusal interferences. Using stringent criteria it might be possible to apply occlusal adjustment therapy without involvement of splint therapy yielding a similar therapy efficacy and with advantages of a shorter treatment duration and lower costs. All types of therapy diminished not only facial pain but also pain of neck and shoulder areas.     

应用(牙合)分离时间延长理论治疗肌筋膜疼痛综合征

目的 :　研究新的调牙合方法治疗肌筋膜疼痛综合征 (MPD)。方法 :　以牙合分离时间延长理论为指导、计算机为辅助手段 ,对 2 5例MPD患者进行调牙合治疗。结果 :　多数病例的症状在 2～ 3周内缓解或消失 ,无明显不良反应 ,关节区不适疼痛、咬肌区不适疼痛和颞肌区头疼不适等三大症状治疗有效率分别达到 89%和 10 0 %,观察一年疗效稳定。结论 :　对保守治疗无效的MPD患者 ,可以考虑使用新的调牙合方法治疗。     

磨牙症患者（牙合）接触特征的研究

目的 :研究磨牙症患者牙合接触的特征 ,探索牙合因素与磨牙症的关系。方法 :用T -scanII型咬合分析仪对 2 3名磨牙症患者与 13名对照者分别进行正中牙合位、前伸及侧方运动的咬合检查 ,测量闭合接触时间、前伸与侧方牙合分离时间 ,观察平衡侧牙合干扰出现的情况。结果 :磨牙症患者的闭合时间小于对照组 ;侧方牙合分离时间比对照组长 ;与对照组相比多数磨牙症患者出现平衡侧牙合干扰。结论 :平衡侧牙合干扰可能是与磨牙症有密切关系的重要的牙合因素     

T-ScanⅢ应用于牙根纵裂患者咬合特征分析的初步研究

目的:探讨牙根纵裂(vertical root fractures,VRF)发生的牙合因素。方法:应用T-ScanⅢ咬合分析仪对8例VRF患者及个别正常牙合者分别进行正中及侧方咬合记录,定量数据牙合力百分比值(tooth occlusal force percent-ages,T-FP)、双侧牙合力百分比值(two sides force percentages,TS-FP)、牙合力不对称指数(asymmetry index of occlusal force,AOF)、闭合时间(occlusion time,OT)、侧方牙合分离时间(disclusion time,DT)采用配对资料的符号秩和检验分析,定性数据早接触、牙合力中心点 (center of force,COF) 位置及偏移方向采用Fisher确切概率法检验分析,检验水准α=0.05,P<0.05差异有统计学意义。结果:VRF组T-FP、AOF、OT、DT大于正常对照组,差异具有统计学意义(P<0.05);2组COF位置差异具有统计学意义(P<0.05),TS-FP、早接触发生率、COF偏移方向差异无统计学意义(P>0.05)。结论:VRF患者全口牙合力分布不均衡,双侧 牙合力分布不对称,牙合接触稳定性差。     

TMD患者咬合板治疗后接触变化的研究

目的:比较咬合板治疗颞下颌关节紊乱病(TMD)前后异常因素的变化情况,探讨咬合板治疗TMD的机理。方法:选取34名用咬合板治疗的TMD患者,记录其戴用咬合板后2个月时的咬合特征及临床症状,并与治疗前进行比较。结果:TMD患者治疗后的力中心距中线距离减小,闭合时间与侧方分离时间明显较治疗前缩短,早接触出现率较治疗前降低,但前伸分离时间、非工作侧干扰及前伸干扰的出现率与治疗前相比无显著性差异。结论:咬合板对于纠正力中心位置、减小早接触的发生率、缩短闭合时间及侧方分离时间具有明显的作用,能够使TMD患者的关系向着更加协调、稳定的方向发展,是其有效治疗TMD的重要机理。     

伴颞下颌关节紊乱病症状的偏侧咀嚼者咬合分析

目的 采用TeeTester数字化咬合系统比较分析伴颞下颌关节紊乱病（TMD）症状的偏侧咀嚼者和非偏侧咀嚼者的咬合情况。方法 根据调查问卷和口腔检查筛查出80名受试者,分为4组：伴TMD症状的偏侧咀嚼者20名,不伴TMD症状的偏侧咀嚼者20名,伴TMD症状的非偏侧咀嚼者20名,不伴TMD症状的非偏侧咀嚼者20名。使用TeeTester数字化咬合系统测定4组对象的全牙列最大接触面积、全牙列最大咬合力、力不对称指数、咬合力中心点、咬合接触时间、分离时间等。采用SPSS 25.0软件进行统计分析。结果 牙尖交错位时,4组的全牙列最大咬合力、最大咬合接触面积差异有统计学意义（P<0.05）;伴/不伴TMD症状的偏侧咀嚼组习惯侧与非习惯侧咬合力分布比较差异有统计学意义（P<0.05）;4组的咬合力中心点、中心点偏移方向、中心点距中线垂直距离差异有统计学意义（P<0.05）。经Spearman相关性分析,习惯侧最大咬合力、习惯侧最大接触面积、咬合力中心点与偏侧咀嚼呈正相关（P<0.05）,全牙列最大咬合力、最大接触面积与TMD呈负相关（P<0.05）。结论 1）伴T...     

青年夜磨牙症患者经弹性牙合垫治疗前后咬合变化特征的研究

目的：：测量并分析夜磨牙症患者使用弹性垫治疗前后各项咬合数据变化。方法：使用弹性垫对青年夜磨牙症患者(n=10)进行治疗,并在治疗前和治疗后6个月使用T-Scan咬合检测仪进行咬合检测,观察和记录实验组闭合时间、分离时间、力中心位置、力不对称指数的变化,与对照组( n=10)进行对比和研究,并观察临床疗效。结果：治疗前实验组闭合时间及左、右侧分离时间均比对照组长(P<0.05),治疗后均无统计学差异(P>0.05);治疗前、后2组前伸分离时间差别无统计学意义(P>0.05);治疗前实验组和对照组力中心位置左右向偏移和右侧力百分比及力不对称指数比较均有统计学差异(P<0.05),治疗后比较均无统计学差异(P>0.05)。实验组治疗后闭合时间及左、右侧分离时间均比治疗前缩短(P<0.05);实验组治疗前、后右侧力百分比值有统计学差异(P<0.05),前伸分离时间、力中心位置偏移、左侧力百分比及力不对称指数治疗前后比较均无统计学差异(P>0.05)。结论：早接触、侧方干扰、全牙列力中心的偏移等咬合因素与磨牙症有十分密切的关系。使用弹性垫治疗磨牙症,可以有效地改善上述问题,使关系更加协调和稳定。     

Masticatory muscle activity before and after elimination of balancing side occlusal interference

The activity of the masseter and anterior and posterior temporal muscles was studied by electromyography (EMG) in thirteen subjects with unilateral balancing side interferences and in twelve control subjects without such interferences. In both groups the EMG recordings were made during postural activity and various functions of the masticatory system and in the interference group they were repeated on two occasions following occlusal adjustment. The postural muscle activity was significantly lower in the interference than in the control group while there was no difference during maximal bite. The number of chewing cycles was greater and the act of chewing was somewhat longer in the interference than in the control group. During swallowing of water the maximal mean voltage amplitude was smaller in the interference than in the control group. The findings are discussed in relation to previous results and the conflicting ideas concerning occlusal factors in the aetiology of mandibular dysfunction.     

The influence of immediate complete anterior guidance development technique on subjective symptoms in Myofascial pain patients: Verified using digital analysis of occlusion (Tek-scan) for analysing occlusion: A 3 years clinical observation

Objectives:

The purpose of this study is to evaluate the effect of occlusal equilibration using immediate complete anterior guidance development (ICAGD) technique by Kerstein and Farrell on the subjective symptoms of myofascial pain. This technique is the most advanced verifiable and measurable way of digitally analyzing the occlusion using T-scan technology. The primary objective is to reduce the anterior disclusion time to <0.4 s and the secondary objective is to reduce the signs and symptoms of myofascial pain.

Materials and Methods:

This study is to assess the reducing effects of subjective symptoms of 100 patients diagnosed as myofascial pain patients treated by ICAGD technique as described by Kerstein and Farrell. The common complaints of the patients were a pain in the masseter and temporal muscles, jaw tiredness in the mornings, night bruxing and difficulty in chewing. In this technique occlusal equilibration involves removal of posterior interferences and establish anterior guidance. The patients were treated over three visits 1-week apart and followed for 3 years with an interval of 3 months for the subsequent visits. A visual analog ordinal scale is used to rate the symptoms. The symptoms reduction occurred for all the patients after the first correction in about 5–10 days. In about a period of 3 years review, no recurrence was seen of the chronic myofascial symptoms.

Results:

In spite of the chronic nature of the patient''s symptoms, symptom reduction occurred in a week''s time. This was assessed by the results of the ordinal scale values. This agrees with the studies of Kerstein and Farrell.

Conclusion:

Equilibration of occlusion using digital analysis by T-scan in which force is quantified against time, should be done to establish free functional movements without any interference; otherwise the disturbances in the excursive movements may lead to muscle dysfunction at later years.Key Words: Digital analysis of occlusion, electromyography, enameloplasty, immediate complete anterior guidance development, joint vibratography, myofascial pain, occlusal discrepancy, T-scan     

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.     

Effect of occlusal splints on the electromyographic activities of masseter muscles during maximum clenching in patients with myofascial pain-dysfunction syndrome

Integrated EMG activities of masseter muscles during maximum voluntary isometric contraction with and without full-arch maxillary stabilization splints were observed in patients with MPD syndrome having occlusal interferences and in healthy subjects having no occlusal interferences. The masseter muscle activity was more significantly reduced in patients with MPD syndrome during maximum clenching with splints than in those patients without splints. In healthy subjects, such a significant difference could not be observed with and without splints. This finding suggests that the elimination of the occlusal interferences by means of occlusal splints could reduce the degree of sensory information from the periodontal receptors during nocturnal clenching or grinding. This could result in a decrease in masseter muscle activity giving rise to muscular relaxation.     

EMG and pain severity evaluation in patients with TMD using two different occlusal devices

PURPOSE: The purpose of this study was to compare the electromyographic (EMG) activity level and signs and symptoms in patients with myogenous temporomandibular disorders (TMD) treated with two different types of occlusal devices. MATERIALS AND METHODS: Eleven TMD patients were treated with maxillary occlusal devices. The first group received a flat-plane stabilization occlusal device, while the second group received an anatomic occlusal device that maintained the anatomy of the original occlusal surfaces. The severity of signs and symptoms and the masseter EMG activity were recorded and evaluated before treatment and at 72 hours, 2 weeks, and 4 weeks following the delivery of the occlusal device. EMG activity was measured during maximum clenching and during chewing on the right and left sides. The EMG was also recorded for seven normal subjects as a control group. RESULTS: All patients showed reduction of reported and clinically found muscle pain, with no statistically significant differences between the two groups. A reduction in the EMG activity level at maximum clenching was seen in both patient groups, but was significant only with the anatomic occlusal device. Mean EMG activity during chewing was highly variable within and between groups. CONCLUSION: The subjective and objective improvements with both types of occlusal devices suggest that either type of occlusal device can be beneficial to TMD patients.     

The relationship between the occlusal interference side and the symptomatic side in temporomandibular disorders

This study aimed to investigate the relationship between the facial side of pain or clicking symptoms and the side of occlusal interference, and to examine the features of pain and clicking patients in terms of frequencies of occlusal interferences in relation to the symptomatic side. Occlusal conditions in 31 pain patients and 40 clicking patients were investigated just after the relief of pain or clicking solely by means of bite plane therapy. The symptomatic side did not associate with the side of fewer occlusal contacts in intercuspal position, no canine contact on the working side, occlusal contact on the non-working side, or unilateral contact in retruded contact position. The results of this study suggest that pain or clicking does not necessarily tend to appear on the side of these occlusal interferences. Additionally, characteristic inclination for pain and clicking patients in terms of frequencies of occlusal interferences in relation to the symptomatic side was not identified.     

Effects of occlusal adjustment on the periodontal condition and on the symptoms of masticatory dysfunction in patients treated with fixed prosthesis–a one-year follow-up study

A total of fifty-nine patients treated with a fixed prosthesis 4 years previously were recalled for a clinical and radiological examination. The subjects studied consisted of two groups: in group A the teeth of the patients with TMJ symptoms were selectively ground, whereas no grinding was performed in group B. At the first examination, occlusal interferences were found in 43.0% of the crowns and in 29.0% of pontics in group A before occlusal adjustment. At the second examination 1 year later, the percentage of occlusal interferences was decreased in this group (33.0% of the crowns and 25.8% in the pontics). In group B no changes in occlusal interferences were found after the 1-year follow-up period. The results of the investigation suggested that the frequency of interferences related to occlusal adjustment is important and the effect of occlusal adjustment to periodontal condition and TMJ symptoms is beneficial.     

Short-term effect of occlusal adjustment on craniomandibular disorders including headaches

The aim of this study was to assess the short-term effect of occlusal adjustment on craniomandibular disorders. Fifty patients were randomly selected and divided into a treatment (T) and a control (C) group. The initial clinical examination and the follow-up were made by one observer and the occlusal adjustment by another. There were no significant differences between groups with regard to frequency of headaches, facial pain, pain on mandibular function, or duration of headaches and facial pain. Fifty-two percent of the patients in the treatment group and 20% of the patients in the control group reported reduced subjective symptoms overall at follow-up examination. The improvement was statistically significant within the T group and significantly greater than in the C group. There was no significant change within or between groups with regard to frequency of headaches, facial pain, or pain on mandibular movements. There was an almost significant difference between groups after treatment with regard to changes in the number of tender muscles. The results of this study indicate that occlusal adjustment provides a general subjective improvement of craniomandibular disorders.     

Muscular activity disorders in relation to intentional occlusal interferences

The electromyographic activity (EMG) of the anterior temporal (AT), masseter (M), trapezius (T) muscles and anterior aspect of the digastric (D) was measured in 50 subjects, during six seconds of maximum contraction, bilaterally with and without unilateral premature contacts and individually for each tooth. Special occlusal interferences were designed to assess muscular activity. Muscular activity was measured simultaneously by placing premature contacts on each tooth, under T-Scan monitoring. Premature contacts reduced EMG activity during maximum contraction of the AT, D and M muscles, the highest disruption is in the AT muscle, at the level of upper right 2nd molar, with a 56% reduction in activity. Conversely, there was an increase of activity of the T muscle in all teeth when placing artificial occlusal premature contacts, with the highest difference in the upper right 1st bicuspid. Therefore, occlusal interferences can cause neuromuscular disruptions, thus inducing important muscular discrepancy. Both the EMG and T-Scan monitoring can be considered suitable methods to use in daily dental practice to identify premature contacts and to measure EMG activity.     

颞下颌关节紊乱病患者牙合接触特征的研究

目的　研究颞下颌关节紊乱病 (tempromandibulardisorders,TMD)患者的牙合接触特征。方法　应用T ScanII咬合分析仪对 32例TMD患者进行牙尖交错位、前伸及侧方运动的咬合检查并与正常组对照。结果　TMD患者的牙合力中心偏离中线的程度大于对照组 ,闭合时间与牙合分离时间明显较对照组延长 ,早接触出现率明显高于对照组 ,但非工作侧牙合干扰及前伸牙合干扰的出现率与对照组差异无显著性。结论　早接触是与TMD发病有密切关系的牙合因素 ,牙合力中心、闭合时间与牙合分离时间可作为判断TMD病变程度及治疗效果的参考依据。     

Myofascial temporomandibular disorder pain, parafunctions and psychological stress

Associations of evening and morning masticatory muscle pain and nocturnal electromyography (EMG) activity with psycho-behavioural factors and occlusal splint therapy were studied during a 20-week study-protocol. Over a period of almost 2 years, only eight of the 120 eligible patients were willing to enroll the study protocol. Further, four of the eight participants dropped out during the study, and approximately 20-30% of the nocturnal EMG recordings failed. Because of the impractical and unworkable nature of the protocol, the study was prematurely terminated and the results of the four remaining individuals are reported here as single-patient clinical trials. Univariate and multiple regression analyses revealed that in three of the four patients, changes in nocturnal EMG activity were associated with the period of splint therapy. However, no associations were found between the changes in nocturnal EMG activity and the observed changes in muscle pain. In two patients, the changes in muscle pain were associated with the period of splint therapy and with the changes in psychological stress. Within the limitations of single-patient clinical trials, it can be concluded that changes in chronic masticatory muscle pain seem to be more related to changes in psychological stress than to those in parafunctional activities.