The effects of an occlusal splint on the electromyographic activities of the temporal and masseter muscles during maximal clenching in patients with a habit of nocturnal bruxism and signs and symptoms of craniomandibular disorders

The effects of a full arch maxillary plane occlusal splint on the level of electromyographic (EMG) activity in the anterior temporal and masseter muscles during maximal clenching were studied in 31 patients with a habit of nocturnal bruxism and signs and symptoms of craniomandibular disorders, before and after occlusal splint therapy. The results showed, before treatment, that the occlusal splint changed significantly (in 71% of patients) the level of EMG activity during maximal clenching. However, these changes were not consistent and differed between patients and even, in some patients, between muscles. After long-term occlusal splint therapy and improvement of the signs and symptoms of craniomandibular disorders, the number of patients who had an identical level of EMG activity during maximal clenching in the intercuspal position and on the occlusal splint tended to increase. Moreover, in these patients the level of symmetry of action in pairs of muscles during maximal clenching was strong, and the splint did not change this level of symmetry.     

The effects of stabilization splint treatment on the volume of masseter muscle in sleep bruxism patients

Objective: The aim of this study was to evaluate, quantitatively, the volumetric effects of stabilization splint therapy on the masseter muscle of sleep bruxism (SB) patients.

Methods: The magnetic resonance (MR) images of 16 SB patients diagnosed by polysomnography (PSG) who used stabilization splints for four months were obtained before and after the therapy. The masseter muscle volume was calculated using Cavalieri’s principle on the MR images.

Results: After the splint therapy, the mean volume of the masseter muscle did not reduce significantly. The fat and/or water content of the muscles did not change either.

Discussion: The stabilization splint therapy had no effect on the volume, fat and/or water content of the masseter muscle; however the discomfort was reduced in the patients. Although the effect of splint therapy is not fully understood, the non-invasive and reversible stabilization splint can be used in SB patients because of its relaxation effect on muscles.     

An electromyographic study of the immediate effect of an occlusal splint on the postural activity of the anterior temporal and masseter muscles in different body positions with and without visual input

With the mandible at rest, the clinical postural position was measured and electromyographic recordings (in seated and supine position, eyes open and eyes closed, before as well as 15 min after insertion of an occlusal splint) were from the anterior temporal and masseter muscles in thirty-one patients with signs and symptoms of mandibular dysfunction and nocturnal bruxism. The results indicated that when the patients were seated upright, there was a distinct postural activity in the anterior temporal and in some patients also in the masseter muscles. This postural activity decreased significantly with closure of the eyes and in supine position. Fifteen minutes after insertion of an occlusal splint, the postural activity in the temporal muscles decreased in 52%, increased in 22% and remained unchanged in 26% of the patients. Moreover, the postural activity reached its lowest level in supine position. The results indicate that the supine position is the body position to be preferred for centric relation recording as well as for occlusal and splint adjustment.     

肌位咬合板对颅颌功能紊乱者下颌运动影响的研究

研究肌位咬合板对颅颌功能紊乱患者下颌运动的影响。方法：采用下颌运动轨迹描记信,记录99例患者戴板前和即刻置入咬合板后自姿势位（MPP）至牙尖交错（ICO）、自然张闭口及最大最快张闭口运动;孪-吞个月后复查（不戴板）。结果：戴板后87．8％CMD患者由MPP闭合至ICO侧后移消失,自然张闭口轨迹一致率由戴板前4％提高到78.8％,最大最快张闭口运动轨迹规则度由15.2％提高至89.9％,速度也显著增加（P＜0.05）.复查显示:咬合正常者MPP至ICP侧后消失,张闭口轨迹一致,速度轨迹规则,速度增加,咬合异常者下颌运动与治疗前相比无变化.结论:肌位咬合板对CMD治疗机理之一是调整异常的下颌运动.     

肌位咬合板对颅颌功能紊乱者咀嚼肌肌电图的影响

目的：研究肌位咬合板对颅颌功能紊乱（ Ｃ Ｍ Ｄ）患者咀嚼肌肌电的影响,探讨其作用机理。方法：采用美国 Ｅ Ｍ２ 型肌电仪记录１０２ 例患者带咬合板前后的姿势位（ Ｍ Ｐ Ｐ）及牙尖交错位（ Ｉ Ｃ Ｐ）最大紧咬时的肌电变化。结果：（１）即刻戴入咬合板后颞肌前束（ Ｔ Ａ）与嚼肌（ Ｍ Ｍ）的 Ｍ Ｐ Ｐ高电位明显降低（ Ｐ＜ ０．０５）;治疗后不戴咬合板复查, Ｔ Ａ、颞肌后束（ Ｔ Ｐ）和 Ｍ Ｍ 肌紧张缓解。（２）戴咬合板紧咬双侧 Ｔ Ａ、 Ｔ Ｐ 和 Ｍ Ｍ 的肌电活动显著减小（ Ｐ＜ ０．０５）, Ｍ Ｍ 的肌电活动对称性明显提高（ Ｐ＜ ０．０５）,活动指数显著增加（ Ｐ＜０．０５）。结论：肌位咬合板能明显降低升颌肌最大紧咬的肌电活动,提高嚼肌的肌电活动对称性及活动指数。     

The silent period in the masseter and the anterior temporal muscles at repeated registrations

Three dental nurses took part in an investigation of the reproducibility of the EMG silent period. The latency and duration of the silent period after tooth tapping and jaw jerk were found to be rather stable within the same day and between recordings every other day for 10 days. No differences in the SP variables between right and left side were found. Differences in the latency and duration of the silent period between the masseter and anterior temporal muscles during tooth tapping and jaw jerk were registered. The findings suggest functional difference between the two muscles.     

A clinical and electromyographic study of the long-term effects of an occlusal splint on the temporal and masseter muscles in patients with functional disorders and nocturnal bruxism

The postural activity of the temporal and masseter muscles in thirty-one patients with signs and symptoms of functional disorders were studied: before, during and after 3-6 months of occlusal splint therapy. The fluctuating signs and symptoms, as well as the postural activity of the temporal and masseter muscles were significantly reduced after treatment. Further, the coefficients of correlation within pairs of postural activity of the right and left muscles increased significantly. After cessation of the splint therapy the signs and symptoms recurred to the pre-treatment level within 1-4 weeks in about 80% of the patients. The results indicate that an occlusal splint can eliminate or diminish signs and symptoms of functional disorders and re-establish symmetric and reduced postural activity in the temporal and masseter muscles, which can facilitate procedures, such as functional analysis and occlusal adjustment.     

Temporalis and masseter muscle activity in patients with anterior open bite and craniomandibular disorders

Abstract – Activity in temporalis and masseter muscles, and traits of facial morphology and occlusal stability were studied in 22 patients (19 women, 3 men; 15–45 yr of age) with anterior open bite and symptoms and signs of craniomandibular disorders. Facial morphology was assessed by profile radiographs, occlusal stability by tooth contacts, and craniomandibular function by clinical and radiological examination. Electromyographic activity was recorded by surface electrodes after primary treatment with a reflex-releasing, stabilizing splint. Maximal voluntary contraction was reduced compared to reference values, particularly in subjects with muscular affection, but maximal activity increased significantly when biting on the splint. Maximal voluntary contraction was positively correlated to molar contact and negatively to anterior face height, mandibular inclination, vertical jaw relation and gonial angle. Relative loading of the muscles was markedly increased during resting posture. It was concluded that reduced occlusal stability and long-face morphology were associated with weak elevator muscle activity with disposition overload and tenderness. The results also indicated that increase of occlusal stability might lead to increased muscle strength and possibly reduce risk of physical strain.     

Temporalis and masseter muscle activity in patients with anterior open bite and craniomandibular disorders

Activity in temporalis and masseter muscles, and traits of facial morphology and occlusal stability were studied in 22 patients (19 women, 3 men; 15-45 yr of age) with anterior open bite and symptoms and signs of craniomandibular disorders. Facial morphology was assessed by profile radiographs, occlusal stability by tooth contacts, and craniomandibular function by clinical and radiological examination. Electromyographic activity was recorded by surface electrodes after primary treatment with a reflex-releasing, stabilizing splint. Maximal voluntary contraction was reduced compared to reference values, particularly in subjects with muscular affection, but maximal activity increased significantly when biting on the splint. Maximal voluntary contraction was positively correlated to molar contact and negatively to anterior face height, mandibular inclination, vertical jaw relation and gonial angle. Relative loading of the muscles was markedly increased during resting posture. It was concluded that reduced occlusal stability and long-face morphology were associated with weak elevator muscle activity with disposition overload and tenderness. The results also indicated that increase of occlusal stability might lead to increased muscle strength and possibly reduce risk of physical strain.     

Surface EMG frequency dependence on force in the masseter and the anterior temporal muscles

Myoelectric power spectrum analysis was used to study isometric contractions, 10-15 s long, of the masseter muscles and the anterior temporal muscles. Surface EMG activity was recorded from these muscles for nine females while biting on a bite force transducer up to maximal effort (100% maximal voluntary contraction; MVC). The mean frequency (MF) was calculated as a single estimate of the myoelectric power spectrum. Regression analyses were made of MF versus bite force (0-100% MVC). The mean MF values of all females' masseter muscles increased up to 55-60% MVC. For the anterior temporal muscles no increase in mean MF was found above 20-25% MVC. The increase in MF was possibly dependent on recruitment of type I fibers and low-pass tissue filtering effects. The slope of regression for the force level 0-60% MVC was intraindividually steeper for the masseter muscles than for the anterior temporal muscles. A similar decrease in mean MF was found for the masseter muscles and the anterior temporal muscles for the force level 60-100% MVC. The possibility of muscular fatigue was discussed.     

Surface EMG frequency dependence on force in the masseter and the anterior temporal muscles

Abstract – Myoelectric power spectrum analysis was used to study isometric contractions, 10–15 s long, of the masseter muscles and the anterior temporal muscles. Surface EMG activity was recorded from these muscles for nine females while biting on a bite force transducer up to maximal effort (100% maximal voluntary contraction; MVC). The mean frequency (MF) was calculated as a single estimate of the myoelectric power spectrum. Regression analyses were made of MF versus bite force (0–100% MVC). The mean MF values of all females' masseter muscles increased up to 55–60% MVC. For the anterior temporal muscles no increase in mean MF was found above 20–25% MVC The increase in MF was possibly dependent on recruitment of type I fibers and low-pass tissue filtering effects. The slope of regression for the force level 0–60% MVC was intraindividually steeper for the masseter muscles than for the anterior temporal muscles. A similar decrease in mean MF was found for the masseter muscles and the anterior temporal muscles for the force level 60–100% MVC The possibility of muscular fatigue was discussed.     

Effect of muscle relaxation splint therapy on the electromyographic activities of masseter and anterior temporalis muscles

The purpose of this study was to compare the effectiveness of splint therapy on the electromyographic activity of masticatory muscles (anterior temporalis and masseter) before and after the application of a muscle relaxation splint. Electromyography recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in the intercuspal position both before and after treatment without a splint. Fourteen patients whose chief complaint was masticatory muscle pain were selected for the study. After the initial evaluations muscle relaxation splints were applied, and the patients were instructed to use the splints for 6 weeks. Surface electromyographic recordings were taken from each patient before the beginning of clinical therapy and after 6 weeks of wearing the splints. The data obtained were analyzed through paired sample t tests and Wilcoxon's signed rank tests. The results of the study were as follows: (1) the electromyographic activity of the two muscles during maximal biting was not markedly changed after the muscle relaxation splint was used; and (2) the changes observed in electromyographic activity of the involved and noninvolved sides were insignificant as well.     

Skin surface temperature over the temporomandibular joint and masseter muscle in patients with craniomandibular disorder

Skin surface temperature was measured over the temporomandibular joint (TMJ) and over the origin of the superficial portion of the masseter muscle in 59 patients with craniomandibular disorder of different character. Forty patients suffered from disorder of muscular origin, 11 from non-specific arthritis and 8 from symptomatic osteoarthrosis. The degree of mandibular dysfunction was estimated by the clinical dysfunction score and index. The temperature was measured by a thermistor applied to the skin. The clinical dysfunction score of the patients varied between 1 and 25 units. Eleven patients had a clinical dysfunction index of I, 22 had II and 26 had III. The temperature over the TMJ varied between 31.3 degrees C and 36.7 degrees C, and over the masseter muscle between 31.1 degrees C and 35.5 degrees C. The patients with unilateral tenderness to palpation of the TMJ and who were diagnosed to have TMJ arthritis had a higher skin surface temperature over the symptomatic than non-symptomatic joint. It was concluded that tenderness to palpation of the TMJ in patients with TMJ arthritis is associated with raised skin surface temperature over the joint.     

The temporal/masseter co-contraction: an electromyographic and clinical evaluation of short-term stabilization splint therapy in myogenous CMD patients

SUMMARY The short-term effect (3–6 weeks) of the use of a stabilization splint was investigated in a group of 35 myogenous craniomandibular disorder patients. The patients were clinically examined and surface EMG recordings of the temporal and masseter muscles were made during clenching in the intercuspal position (ICP), immediately after the insertion of the splint (SSP), and after at least 3 weeks of splint treatment (SSP 3). With the use of the error variance of the activity index changes in EMG activity were investigated. Three groups of patients were then recognized. One group showed a decrease in temporal muscle activity during splint treatment. Another group did not show any significant change during splint treatment. The third group showed an increase of temporal muscle activity. In general, significant reductions in the amount of static pain were found. In the group with a significant reduction of temporal muscle activity ( n =15) there was a greater decrease in the amount of static pain ( P ≤0.05) than in the group ( n =4) with a significant increase of temporal muscle activity. The results may indicate that the temporal muscle plays an important role in the perception of static pain in the masticatory system.     

肌位牙合板对颅颌功能紊乱者髁突位置及盘突关系异常影响的研究

目的　研究颅颌功能紊乱（ Ｃ Ｍ Ｄ） 者牙尖交错位（ Ｉ Ｃ Ｐ） 的髁位及戴入肌位牙合板后的改变, 对戴入肌位牙合板后颞颌关节（ Ｔ Ｍ Ｊ） 弹响消失者, 观察盘突关系的变化。方法　对１０２ 例 Ｃ Ｍ Ｄ 者在 Ｉ Ｃ Ｐ 及戴入肌位牙合板后咬合接触时, 在断层深度不变的情况, 分别进行双侧 Ｔ Ｍ Ｊ侧位中层摄影, 对其中９ 例戴板后弹响立即消失者行戴板前、即刻戴入牙合板后及治疗后, Ｔ Ｍ Ｊ上腔造影的断层摄影。结果　１０２ 例 Ｃ Ｍ Ｄ 者 Ｉ Ｃ Ｐ 时, 髁突一侧后位或双侧后位４３ 例, 中位４６ 例, 一中一前６ 例, 双侧前位７ 例。戴入牙合板后, 后位者３０ 例双侧居中, 中位者３６ 例前下移,而髁位异常在戴板后持不变者５ 例。９ 例盘突关系异常者, 戴入牙合板后全部恢复正常, 但３ ～６ 月后去板, 仅１ 例盘突关系正常,８ 例仍异常。结论　肌位牙合板可使后位的髁突居中, 居中者前下调位并纠正不对称的髁位, 而对盘突关系异常的调整作用有限。     

Electromyography of the masseter and anterior temporalis muscles in patients with temporomandibular dysfunction

The electromyograms of the masseter and anterior temporalis muscles of 31 patients with clinically definite temporomandibular joint dysfunction have been examined, both in the open-close-clench cycle and by elicitation of the jaw jerk. The results have been compared both metrically and non-metrically with the normal series previously reported (Griffin and Munro, 1969; Munro and Griffin, 1969, and 1971). The incidence of malocclusion was much higher than in the normal series, and centric slides were demonstrated in 24 of the 31 patients.     

Immediate electromyographic response in masseter and temporal muscles to bite plates and stabilization splints

Abstract— The immediate influence on masticatory muscle activity of bite plates and stabilization splints was investigated in control subjects and patients with craniomandibular disorders. Electromyographic surface recordings were performed from the masseter and temporal muscles bilaterally with and without the appliances in situ. In the rest position, no significant change in average activity was registered in any muscle with either appliance. Activity during maximal biting on stabilization splints was not different from that without the appliance while bite plates caused a decrease in activity in both muscles in both groups. The reduced maximal activity was probably due to the smaller number and exclusively anterior positioned occlusal contacts on the bite plate.     

Immediate electromyographic response in masseter and temporal muscles to bite plates and stabilization splints

The immediate influence on masticatory muscle activity of bite plates and stabilization splints was investigated in control subjects and patients with craniomandibular disorders. Electromyographic surface recordings were performed from the masseter and temporal muscles bilaterally with and without the appliances in situ. In the rest position, no significant change in average activity was registered in any muscle with either appliance. Activity during maximal biting on stabilization splints was not different from that without the appliance while bite plates caused a decrease in activity in both muscles in both groups. The reduced maximal activity was probably due to the smaller number and exclusively anterior positioned occlusal contacts on the bite plate.     

EMG power spectrum patterns of anterior temporal and masseter muscles in children and adults

The power spectrum of electromyograms (EMG) has been demonstrated to vary with muscles having different muscle fiber type compositions. This study investigated the variations in EMG power spectrum patterns of the masticatory muscles with age and gender by comparison of the mean power frequency (MPF) of the anterior temporal and masseter muscles in children and adults. Surface EMG signals were sampled bilaterally from the muscles when the subjects were performing maximum voluntary isometric clenches at maximal intercuspal position. The results indicated that MPF values were age-dependent (p less than 0.001), and sexual dimorphism was evident (p less than 0.001), with lower MPF values in male and adult muscles. While male adults had the lowest and female children had the highest MPF values, female adults had MPF values closer to values obtained from male children. These differences or similarities could be attributed to the degree of differentiation of the muscles during growth and development of the craniofacial morphology.