Masticatory muscle sleep background electromyographic activity is elevated in myofascial temporomandibular disorder patients

Despite theoretical speculation and strong clinical belief, recent research using laboratory polysomnographic (PSG) recording has provided new evidence that frequency of sleep bruxism (SB) masseter muscle events, including grinding or clenching of the teeth during sleep, is not increased for women with chronic myofascial temporomandibular disorder (TMD). The current case–control study compares a large sample of women suffering from chronic myofascial TMD (n = 124) with a demographically matched control group without TMD (n = 46) on sleep background electromyography (EMG) during a laboratory PSG study. Background EMG activity was measured as EMG root mean square (RMS) from the right masseter muscle after lights out. Sleep background EMG activity was defined as EMG RMS remaining after activity attributable to SB, other orofacial activity, other oromotor activity and movement artefacts were removed. Results indicated that median background EMG during these non‐SB event periods was significantly higher (P < 0·01) for women with myofascial TMD (median = 3·31 μV and mean = 4·98 μV) than for control women (median = 2·83 μV and mean = 3·88 μV) with median activity in 72% of cases exceeding control activity. Moreover, for TMD cases, background EMG was positively associated and SB event‐related EMG was negatively associated with pain intensity ratings (0–10 numerical scale) on post‐sleep waking. These data provide the foundation for a new focus on small, but persistent, elevations in sleep EMG activity over the course of the night as a mechanism of pain induction or maintenance.     

Ultrasonography as a tool for evaluating treatment of the masseter muscle in temporomandibular disorder patients with myofascial pain

Objectives This study clarified ultrasonography (US) changes after splint therapy and investigated the use of this modality for evaluating treatment of the masseter muscle in temporomandibular disorder (TMD) patients with myofascial pain. Methods Twenty-five female TMD patients with myofascial pain were examined with US before and after splint therapy. The thickness and internal appearance of the masseter muscle were evaluated. Results No differences in thickness were found before and after treatment in either “Improved” or “Not improved” patients. Twelve patients showed changes in the internal appearance. A significant difference was observed in the distributions of types of internal appearance before and after treatment. Three representative cases are presented. Conclusions US has potential for evaluating the masseter muscle in TMD patients with myofascial pain, especially muscles that appear edematous before treatment.     

Effect of experimental jaw muscle pain on EMG activity and bite force distribution at different level of clenching

Bite force at different levels of clenching and the corresponding electromyographic (EMG) activity in jaw‐closing muscles were recorded in 16 healthy women before, during and after painful stimulation of the left masseter muscle. Experimental pain was induced by infusion of 5·8% hypertonic saline (HS), and 0·9% isotonic saline (IS) was infused as a control. EMG activity was recorded bilaterally from the masseter and temporalis muscles, and static bite force was assessed by pressure‐sensitive films (Dental Pre‐scale) at 5, 50 and 100% of maximal voluntary contraction (MVC) during each session. Visual feedback was applied by showing EMG activity to help the subject perform clenching at 5, 50 and 100% MVC, respectively. EMG activity at 100% MVC in left and right masseter decreased significantly during painful HS infusion (1·7–44·6%; P < 0·05). EMG activity at 5% and 50% MVC was decreased during HS infusion in the painful masseter muscle (4·8–18·6%; P < 0·05); however, EMG activity in the other muscles increased significantly (18·5–128·3%; P < 0·05). There was a significant increase in bite force in the molar regions at 50% MVC during HS infusion and in the post‐infusion condition (P < 0·05). However, there were no significant differences in the distribution of forces at 100% MVC. In conclusion, experimental pain in the masseter muscle has an inhibitory effect on jaw muscle activity at maximal voluntary contraction, and compensatory mechanisms may influence the recruitment pattern at submaximal efforts.     

Treatment for TMD with occlusal splint and electromyographic control: application of the FARC protocol in a Brazilian population

The purpose of this study was to apply Functional Anatomy Research Center (FARC) Protocol of TMD treatment, which includes the use of a specific type of mandibular occlusal splint, adjusted based on the electromyographic index, in a group of 15 patients with disc displacement, classified according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and then analyzing the results compared with the control group. The clinical evaluations were completed both before and after the treatment. Electromyographic (EMG) data was collected and recorded on the day the splint was inserted (visit 1), after one week (visit 2) and after five weeks of treatment (visit 3). The control group consisted of 15 asymptomatic subjects, according to the same diagnostic criteria (RDC/TMD), who were submitted to the same evaluations with the same interval periods as the treatment group. Immediately after splint adjustment, masseter muscle symmetry and total muscular activity were significantly different with than without the splint (p < 0.05), showing an increased neuromuscular coordination. After treatment, significant variations (p < .05) were found in mouth opening and in pain remission. There were no significant differences among the three sessions, either with or without the splint. There were significant differences between the TMD and control groups for all analyzed indices of muscular symmetry, activity and torque, with the exception of total muscular activity. The use of the splint promoted balance of the EMG activities during its use, relieving symptoms. EMG parameters identified neuromuscular imbalance, and allowed an objective analysis of different phases of TMD treatment, differentiating individuals with TMD from the asymptomatic subjects.     

2种咬合板治疗颞下颌关节紊乱病的临床疗效分析

目的：研究松弛型咬合板和稳定型咬合板治疗颞下颌关节紊乱病(TMD)的疗效。方法：选择以口颌面部疼痛为主诉的TMD患者68例(急性30例,慢性38例),每组分别戴用松弛型咬合板和稳定型咬合板,比较分析治疗前、后颞肌前束(TA)、咬肌(MM)肌电值及关节疼痛强度的变化。采用SPSS 11.0 软件包对数据进行方差分析和t检验。结果：①静息状态下,2种咬合板治疗后,患者双侧TA及MM肌电电位均较治疗前显著下降(P<0.05)。②紧咬状态下,松弛型咬合板治疗的急性组患者双侧TA及MM肌电电位均较治疗前显著上升,而慢性组患者仅双侧MM肌电电位较治疗前显著上升(P<0.05);稳定型咬合板治疗组患者双侧TA肌电电位治疗前后无显著差异,仅双侧MM肌电电位较治疗前显著上升。③2种咬合板治疗后,患者疼痛指数均较治疗前显著下降;但松弛型咬合板治疗后,在功能状态下,急性组患者疼痛缓解的程度更显著。结论：松弛型和稳定型咬合板均对咀嚼肌有松弛作用,能缓解TMD疼痛,但松弛型咬合板治疗急性TMD患者的疗效更加显著。     

Efficacy of stabilisation splint therapy combined with non‐splint multimodal therapy for treating RDC/TMD axis I patients: a randomised controlled trial

Stabilisation splint therapy has long been thought to be effective for the management of temporomandibular disorders (TMD). However, the superiority of stabilisation splint therapy compared to other TMD treatments remains controversial. The aim of this study was to determine the efficacy of stabilisation splint therapy combined with non‐splint multimodal therapy for TMD. A total of 181 TMD participants were randomly allocated to a non‐splint multimodal therapy (NS) group (n = 85) or a non‐splint multimodal therapy plus stabilisation splint (NS+S) group (n = 96). Non‐splint multimodal therapy included self‐exercise of the jaw, cognitive–behavioural therapy, self‐management education and additional jaw manipulation. Three outcome measurements were used to assess treatment efficacy: mouth‐opening limitation, oro‐facial pain and temporomandibular joint sounds. A two‐factor repeated‐measures analysis of variance (anova ) was used to evaluate the efficacy of the two treatment modalities (NS vs. NS+S), and Scheffe's multiple comparison test was used to compare the treatment periods. Subgroup analyses were performed to disclose the splint effects for each TMD diagnostic group. All three parameters significantly decreased over time in both groups. However, there were no significant differences between the two treatment groups in the total comparison or subgroup analyses; an exception was the group with degenerative joint disease. No significant difference between the NS and NS+S treatment approaches was revealed in this study. Therefore, we conclude that the additional effects of stabilisation splint are not supported for patients with TMD during the application of multimodal therapy.     

Two repetitive bouts of intense eccentric‐concentric jaw exercises reduce experimental muscle pain in healthy subjects

High‐intensity eccentric‐concentric contractions of the jaw‐closing muscles induce muscle soreness, fatigue and functional impairment of the jaw, resembling the symptoms of myalgia, according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). However, it is claimed that repetition of similar exercises can minimise these detrimental effects. This study aimed to evaluate the response of jaw‐closing muscles following two series of intense eccentric‐concentric exercises of the masticatory muscles in healthy subjects. Twelve pain‐free participants underwent 2 sessions of intense eccentric‐concentric jaw exercises, with 1‐week interval in between. Each session of jaw exercises comprises 6 sets of 5‐minute‐long bouts of concentric‐eccentric contractions. Self‐reported muscle fatigue and pain, maximum mouth opening without pain (MMO), pain pressure thresholds (PPTs) of temporalis and masseter muscles and maximum voluntary bite force (MVBF) were recorded before, immediately after, 24 and 48 hours after each bout of exercises. ANOVA for repeated measurements was used to analyse the data. During session 2, muscle pain and fatigue were statistically significantly decreased (P < .05) as compared to session 1. Furthermore, statistically significant increases of MVBF (P < .005), MMO (P < .005) and PPTs (P < .005) were found at session 2 as compared to session 1. Within the limitations of the study, is can be concluded that the repetition of eccentric‐concentric jaw‐closing exercises results in signs of muscle training. Future studies can elucidate whether this motor training might be useful for the treatment of myalgia.     

Correlation of splint therapy outcome with the electromyography of masticatory muscles in temporomandibular disorder with myofascial pain

Abstract

Objectives. The aim of this study was to assess the effect of occlusal splint therapy on the electromyographic amplitude records (μV) of masticatory muscles in temporomandibular disorder (TMD) with myofascial pain and to detect a possible existence of a relationship between this effect and the treatment outcome. Materials and methods. Forty patients (23 females and 17 males) having TMD with myofascial pain were included in this study. They were randomly divided into two equal groups (20 of each). The first group (A) was treated by occlusal splints for 6 months while the second group (B) acted as a control. A clinical assessment and surface electromyography (EMG) for the masticatory muscles were performed at the beginning of the study, then 6 months later. The collected data were statistically analyzed using paired t-test. The differences were considered significant at p < 0.05. Results. The results showed that 85% of group A either completely recovered (35%) or clinically improved (50%) while only 20% of group B had a spontaneous improvement. In group A, the means of the electromyographic amplitude records (μV) of the monitored muscles have decreased after 6 months. However, the decrease was statistically insignificant (p > 0.05) in the patients (15%) who had no clinical changes. In group B, the means of the muscles' records (μV) in the left side slightly increased while those of the right side slightly decreased. These changes were statistically insignificant (p > 0.05). Conclusions. Occlusal splint could eliminate or improve the signs and symptoms of TMD patients with myofascial pain. It reduces the electromyographic amplitude records (μV) of the masticatory muscles. The splint therapy outcome has a correlation with the electromyographic amplitude changes of the masticatory muscles.     

Temporomandibular disorder symptoms and their association with quality of life,emotional states and sleep quality in South‐East Asian youths

Population studies on the prevalence of temporomandibular disorders (TMD) and their associations with quality of life (QoL), emotional states and sleep quality in South‐East Asian youths are not available. This cross‐sectional study assessed the presence of TMD and their relationships to QoL, depression, anxiety, stress and sleep quality in a cohort of South‐East Asian adolescents/young adults. Three hundred and sixty‐two students from a polytechnic were enrolled in the study and completed an online questionnaire consisting of the Fonesca's Anamnestic Index (FAI), Oral Health Impact Profile for TMD (OHIP‐TMD), Depression, Anxiety and Stress Scales‐21 (DASS‐21) and Pittsburgh Sleep Quality Index. The FAI appraises TMD severity while OHIP‐TMD determines the effect of TMD on oral health‐related QoL. Statistical analysis was performed using chi‐square test for categorical data whilst one‐way ANOVA/post hoc Bonferroni's tests were employed for numerical scores (P < 0.05). Of the 244 participants who completed the questionnaires in their entirety (37 males; 207 females, mean age 20.1 ± 3.2 years), 32.4% had mild TMD, 9.4% had moderate TMD and 58.2% were TMD free. The total prevalence of TMD was 41.8% (n = 102) and most OHIP‐TMD domains including functional limitation (P = 0.000), physical pain (P = 0.000), handicapped (P = 0.000) and psychological discomfort (P = 0.001) showed significant differences in mean scores depending on TMD severity. A similar trend was observed for DASS‐21. The majority of participants with TMD (69.6%; n = 71) had poor sleep quality (P = 0.004). TMD appear to be prevalent in South‐East Asian youths with varying severity. Severity of TMD had some bearing on QoL, emotional states as well as sleep quality.     

Differential diagnosis of jaw pain using informatics technology

This study aimed to deduce evidence‐based clinical clues that differentiate temporomandibular disorders (TMD)‐mimicking conditions from genuine TMD by text mining using natural language processing (NLP) and recursive partitioning. We compared the medical records of 29 patients diagnosed with TMD‐mimicking conditions and 290 patients diagnosed with genuine TMD. Chief complaints and medical histories were preprocessed via NLP to compare the frequency of word usage. In addition, recursive partitioning was used to deduce the optimal size of mouth opening, which could differentiate TMD‐mimicking from genuine TMD groups. The prevalence of TMD‐mimicking conditions was more evenly distributed across all age groups and showed a nearly equal gender ratio, which was significantly different from genuine TMD. TMD‐mimicking conditions were caused by inflammation, infection, hereditary disease and neoplasm. Patients with TMD‐mimicking conditions frequently used “mouth opening limitation” (P < .001), but less commonly used words such as “noise” (P < .001) and “temporomandibular joint” (P < .001) than patients with genuine TMD. A diagnostic classification tree on the basis of recursive partitioning suggested that 12.0 mm of comfortable mouth opening and 26.5 mm of maximum mouth opening were deduced as the most optimal mouth‐opening cutoff sizes. When the combined analyses were performed based on both the text mining and clinical examination data, the predictive performance of the model was 96.6% with 69.0% sensitivity and 99.3% specificity in predicting TMD‐mimicking conditions. In conclusion, this study showed that AI technology‐based methods could be applied in the field of differential diagnosis of orofacial pain disorders.     

Association between painful temporomandibular disorders and sleep quality: A systematic review

This review aimed to systematically evaluate the association between painful temporomandibular disorders (TMD) and sleep quality in adults. Observational case-control studies using either RDC/TMD or DC/TMD for TMD diagnostic and validated questionnaires for sleep quality were selected by two reviewers in a two-phase process. A systematic review was conducted in accordance with the PRISMA statement. The search was performed in PubMed/MEDLINE, LILACS, SCOPUS, PsycINFO, Web of Science and Grey literature (ProQuest, Google Scholar and OpenGrey). To be eligible, studies had to include adults (>18 years old), with no language, gender or time of publication restrictions. The quality of the papers was assessed using the Newcastle-Ottawa Scale (NOS). Eight case-control studies were included, with high (4) and moderate (4) quality assessment. Seven studies reported a significant association between the presence of painful TMD and sleep quality (P < .05), while the other found impaired sleep in participants with higher sensitivity to heat pain (P < .001). When pain levels were concerned, using different pain scales, six studies found differences when compared to control groups. One study showed that in non-painful TMD, the PSQI values were not different when compared to the control group. An association exists between painful TMD and sleep quality. The presence of pain seems to strongly impact the sleep quality in TMD patients.     

Efficacy of stabilisation splint treatment on facial pain – 1‐year follow‐up

The aim of this randomised controlled trial was to assess the efficacy of stabilisation splint treatment on TMD‐related facial pain during a 1‐year follow‐up. Eighty patients were randomly assigned to two groups: splint group (n = 39) and control group (n = 41). The patients in the splint group were treated with a stabilisation splint and received counselling and instructions for masticatory muscle exercises. The controls received only counselling and instructions for masticatory muscles exercises. The outcome variables were the change in the intensity of facial pain (as measured with visual analogue scale, VAS) as well as the patients' subjective estimate of treatment outcome. The differences in VAS changes between the groups were analysed using variance analysis and linear regression models. The VAS decreased in both groups, the difference between the groups being not statistically significant. The group status did not significantly associate with the decrease in VAS after adjustment for baseline VAS, gender, age, length of treatment and general health status. The only statistically significant predicting factor was the baseline VAS, which was also confirmed by the mixed‐effect linear model. After 1‐year follow‐up, 27·6% of the patients in the splint group and 37·5% of the patients in the control group reported ‘very good' treatment effects. The findings of this study did not show stabilisation splint treatment to be more effective in decreasing facial pain than masticatory muscle exercises and counselling alone in the treatment of TMD‐related facial pain over a 1‐year follow‐up.     

Posterior scissors‐bite: masticatory jaw movement and muscle activity

Scissors‐bite is a malocclusion characterised by buccal inclination or buccoversion of the maxillary posterior tooth and/or linguoclination or linguoversion of the mandibular posterior tooth. This type of malocclusion causes reduced contact of the occlusal surfaces and can cause excessive vertical overlapping of the posterior teeth. This case–control study is the first to evaluate both masticatory jaw movement and masseter and temporalis muscle activity in patients with unilateral posterior scissors‐bite. Jaw movement variables and surface electromyography data were recorded in 30 adult patients with unilateral posterior scissors‐bite malocclusion and 18 subjects with normal occlusion in a case–control study. The chewing pattern on the scissors‐bite side significantly differed from that of the non‐scissors‐bite side in the patients and of the right side in the normal subjects. These differences included a narrower chewing pattern (closing angle, P < 0·01; cycle width, P < 0·01), a longer closing duration (P < 0·05), a slower closing velocity (P < 0·01) and lower activities of both the temporalis (P < 0·05) and the masseter (P < 0·05) muscles on the working side. In 96% of the patients with unilateral posterior scissors‐bite, the preferred chewing side was the non‐scissors‐bite side (P = 0·005). These findings suggest that scissors‐bite malocclusion is associated with the masticatory chewing pattern and muscle activity, involving the choice of the preferred chewing side in patients with unilateral posterior scissors‐bite.     

Isotonic resistance jaw exercise alters jaw muscle coordination during jaw movements

The aim was to investigate the effects of isotonic resistance exercise on the electro‐myographic (EMG) activity of the jaw muscles during standardised jaw movements. In 12 asymptomatic adults surface EMG activity was recorded from the anterior temporalis and masseter muscles bilaterally and the right anterior digastric muscle during right lateral jaw movements that tracked a target. Participants were randomly assigned to a Control group or an Exercise group. Jaw movement and EMG activity were collected (i) at baseline, before the exercise task (pre‐exercise); (ii) immediately after the exercise task (isotonic resistance at 60% MVC against right lateral jaw movements); (iii) after 4 weeks of a home‐based exercise programme; and, (iv) at 8‐weeks follow‐up. There were no significant within‐subject or between‐group differences in the velocity and amplitude of the right lateral jaw movements either within or between data collection sessions (P > 0·05). However, over the 8 weeks of the study, three of the tested EMG variables (EMG Duration, Time to Peak EMG from EMG Onset, and Time to Peak EMG activity relative to Movement Onset) showed significant (P < 0·05) differences in the five tested muscles. Many of the significant changes occurred in the Control group, while the Exercise group tended to maintain the majority of the tested variables at pre‐exercise baseline values. The data suggest a level of variability between recording sessions in the recruitment patterns of some of the muscles of mastication for the production of the same right lateral jaw movement and that isotonic resistance exercise may reduce this variability.     

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.     

Does breathing type influence electromyographic activity of obligatory and accessory respiratory muscles?

Craniomandibular electromyographic (EMG) studies frequently include several parameters, e.g. resting, chewing and tooth‐clenching. EMG activity during these parameters has been recorded in the elevator muscles, but little is known about the respiratory muscles. The aim of this study was to compare EMG activity in obligatory and accessory respiratory muscles between subjects with different breathing types. Forty male subjects were classified according to their breathing type into two groups of 20 each: costo‐diaphragmatic breathing type and upper costal breathing type. Bipolar surface electrodes were placed on the sternocleidomastoid, diaphragm, external intercostal and latissimus dorsi muscles. EMG activity was recorded during the following tasks: (i) normal quiet breathing, (ii) maximal voluntary clenching in intercuspal position, (iii) natural rate chewing until swallowing threshold, (iv) short‐time chewing. Diaphragm EMG activity was significantly higher in the upper costal breathing type than in the costo‐diaphragmatic breathing type in all tasks (P < 0·05). External intercostal EMG activity was significantly higher in the upper costal breathing type than in the costo‐diaphragmatic breathing type in tasks 3 and 4 (P < 0·05). Sternocleidomastoid and latissimus dorsi EMG activity did not show significant differences between breathing types in the tasks studied (P > 0·05). The significantly higher EMG activity observed in subjects with upper costal breathing than in the costo‐diaphragmatic breathing type suggests that there could be differences in motor unit recruitment strategies depending on the breathing type. This may be an expression of the adaptive capability of muscle chains in subjects who clinically have a different thoraco‐abdominal expansion during inspiration at rest.     

A novel vibratory stimulation‐based occlusal splint for alleviation of TMD painful symptoms: a pilot study

This pilot study introduces a novel vibratory stimulation‐based occlusal splint (VibOS) for management of pain related to temporomandibular disorders (TMD). The study sample consisted of 10 patients (mean age: 40·5 ± 13·7 years, male/female: 3/7) who were using stabilisation splints for more than 2 months prior to the study onset and still complained of pain. Patients utilised the active and inactive VibOS during 15 days in a crossover designed clinical trial. The analysed variables were self‐reported VAS pain levels and number of painful sites to palpation (PSP). Statistical analysis was performed with repeated measures anova . At baseline, mean VAS pain levels for group I and II were 45·6 ± 21·0 mm and 37·4 ± 16·3 mm, respectively. Comparison between these baseline values showed no statistical difference (P > 0·05, unpaired t‐test). In group I, the inactive VibOS caused a slight increase in VAS pain levels, whereas the active VibOS promoted a significant decrease in VAS pain levels and PSP (P < 0·01). In group II, which received the active VibOS first, a significant decrease in VAS levels (P < 0·05) and in PSP (P < 0·01) was observed. No significant decrease in VAS pain levels or PSP (P > 0·05) was observed with the use of the inactive VibOS. In conclusion, this study demonstrated a good tendency of this novel VibOS in the alleviation of painful symptoms related to TMD after a 15‐day management period compared to control VibOS.     

Electromyogram biofeedback training for daytime clenching and its effect on sleep bruxism

Bruxism contributes to the development of temporomandibular disorders as well as causes dental problems. Although it is an important issue in clinical dentistry, no treatment approaches have been proven effective. This study aimed to use electromyogram (EMG) biofeedback (BF) training to improve awake bruxism (AB) and examine its effect on sleep bruxism (SB). Twelve male participants (mean age, 26·8 ± 2·5 years) with subjective symptoms of AB or a diagnosis of SB were randomly divided into BF (n = 7) and control (CO, n = 5) groups to undergo 5‐h daytime and night‐time EMG measurements for three consecutive weeks. EMG electrodes were placed over the temporalis muscle on the habitual masticatory side. Those in the BF group underwent BF training to remind them of the occurrence of undesirable clenching activity when excessive EMG activity of certain burst duration was generated in week 2. Then, EMGs were recorded at week 3 as the post‐BF test. Those in the CO group underwent EMG measurement without any EMG BF training throughout the study period. Although the number of tonic EMG events did not show statistically significant differences among weeks 1–3 in the CO group, events in weeks 2 and 3 decreased significantly compared with those in week 1, both daytime and night‐time, in the BF group (P < 0·05, Scheffé's test). This study results suggest that EMG BF to improve AB tonic EMG events can also provide an effective approach to regulate SB tonic EMG events.     

Subjective, clinical and EMG effects of biofeedback and splint treatment

Patients suffering from myofascial pain dysfunction (MPD) were trained to maintain constant levels of EMG masseter activity with the aid of biofeedback. Treatment effects were compared with the effects of a nightly full-coverage splint and with a no-treatment control group. The biofeedback group showed significantly more improvement in clinical dysfunction and subjective symptoms related to pain and mandibular movement than either the splint group or the control group. The results of the splint group were not substantially different from the control group. The EMG results indicate that during biofeedback the ratio between EMG activity of the trained and the non-trained masseter shifted towards a higher contribution of the trained muscle. This effect was significant at high task levels. During biofeedback EMG task performance improved but this effect did not generalize to non-feedback situations. It is suggested that the treatment effects of biofeedback depend upon the increase in perceived control reported by the biofeedback group.     

Questionable effect of lavage for treatment of painful jaw movements at disc displacement without reduction: a 3‐year randomised controlled follow‐up

The present randomised controlled study compared the 3‐year outcome of local anaesthetics with anaesthetics and lavage in patients suffering from painful temporomandibular joint (TMJ) locking. The study included 45 patients referred for treatment of temporomandibular disorders (TMD) to the Department of Orofacial Pain and Jaw Function, Faculty of Odontology, Malmö University, Malmö, Sweden. All patients received a history questionnaire and clinical examination according to the Research Diagnostic Criteria for TMD, panoramic radiographs and magnetic resonance imaging at baseline. Twenty‐five patients were randomised to anaesthetics alone and 20 patients to anaesthetics and lavage. Three years after treatment, we sent the 37 patients who were available for follow‐up a questionnaire that evaluated pain intensity, physical and emotional functioning, and global improvement. Thirty‐four patients responded. The primary outcome was defined as ≥ 30% pain relief. In an intention‐to‐treat analysis, 28 of 45 patients (62%) reported ≥ 30% pain relief at the follow‐up. At 3 years, improvement in pain relief, physical functioning, emotional functioning and global improvement differed non‐significantly between local anaesthetics and anaesthetics and lavage. Compared with baseline, significant improvements (P < 0·05) in pain intensity, physical functioning, emotional functioning and global changes had occurred in both groups after 3 years. Because outcome measurements in the local anaesthetics and lavage and the local anaesthetics groups differed non‐significantly 3 years after treatment of painful TMJ disc displacement without reduction, use of lavage (50 mL saline) has an equivalent effect as local anaesthetics.