Biofeedback in the treatment of long-term temporomandibular joint pain: an outcome study

Advancing clinical understanding of surface electromyography biofeedback: bridging research, teaching, and commercial applications

INTRODUCTION

Expanding the use of surface electromyography-biofeedback (EMG-BF) devices in different therapeutic settings highlights the gradually evolving role of visualizing muscle activity in the rehabilitation process. This review evaluates their concepts, uses, and trends, combining evidence-based research.

AREAS COVERED

This review dissects the anatomy of EMG-BF systems, emphasizing their transformative integration with machine-learning (ML) and deep-learning (DL) paradigms. Advances such as the application of sophisticated DL architectures for high-density EMG data interpretation, optimization techniques for heightened DL model performance, and the fusion of EMG with electroencephalogram (EEG) signals have been spotlighted for enhancing biomechanical analyses in rehabilitation. The literature survey also categorizes EMG-BF devices based on functionality and clinical usage, supported by insights from commercial sectors.

EXPERT OPINION

The current landscape of EMG-BF is rapidly evolving, chiefly propelled by innovations in artificial intelligence (AI). The incorporation of ML and DL into EMG-BF systems augments their accuracy, reliability, and scope, marking a leap in patient care. Despite challenges in model interpretability and signal noise, ongoing research promises to address these complexities, refining biofeedback modalities. The integration of AI not only predicts patient-specific recovery timelines but also tailors therapeutic interventions, heralding a new era of personalized medicine in rehabilitation and emotional detection.

Behaviour Modification in Dentistry: a Review

The review evaluates the contribution which behaviour modification has made to the outstanding behavioural problems in dentistry: the treatment and management of the fear of routine conservation; the prevention of tooth and gum disease; the management of acute operative pain and chronic facial pain.

Investigations of dental fear and operative pain have been limited perhaps too much to patients, especially children, who attend for dental treatment. Behaviour modification has yet to help adequately those patients who avoid dentists and who may be the most acutely afraid and the most intolerant of dentistry. More adequate contributions here could be made if behavioural sciences were much more satisfactorily taught in dental undergraduate and postgraduate curricula than at present.

Useful contributions to preventive dentistry have already been made. The successful treatment of chronic facial pain will have to depend, at least in part, on a more adequate understanding of the psychophysiological mechanisms of the complaint. The nature of the placebo effect in treatment here also needs to be more thoroughly understood.

Treatment of Dental Fear: Systematic Desensitization or Coping?

Thirty-two extremely anxious dental patients were given a modified form of systematic desensitization. In order to evaluate the importance of cognitive factors, a procedure of cognitive coping was added to the therapy program for half of the patients. Results show that treatment outcome was significantly better for the group without the addition of coping elements. It is suggested that the adverse effect observed may reflect an interference by the cognitively-oriented therapeutic activities with an otherwise effective therapeutic process.

Long-term efficacy of biobehavioral treatment of temporomandibular disorders

This study evaluated the relative long-term efficacy of biofeedback, cognitive-behavioral skills training (CBST), combined biofeedback and CBST (Combined), and no-treatment comparison groups in 108 patients suffering from chronic temporomandibular disorder (TMD). After an initial evaluation, patients were assigned to one of the four treatment conditions. The three biobehavioral treatment interventions consisted of 12 standardized sessions. Patients were reevaluated 1 year after completing treatment. Results demonstrated that patients who received the biobehavioral treatments reported significant improvement in subjective pain, pain-related disability, and mandibular functioning 1 year after receiving treatment. The no-treatment comparison group did not demonstrate such improvements. The combined biofeedback and CBST treatment produced the most comprehensive improvements across all outcome measures. These results again demonstrate the heuristic value of adopting a biopsychosocial perspective to the assessment and treatment of chronic medical/dental disorders such as TMD.

The relative efficacy of three cognitive-behavioral treatment approaches to temporomandibular disorders

The purpose of this study was to evaluate the relative efficacy of different biopsychosocial treatment conditions on patients with chronic temporomandibular disorder. Ninety-four patients with chronic temporomandibular disorder were assigned to either a biofeedback treatment group, a cognitive-behavioral skills training (CBST) treatment group, a combined (combination of biofeedback/CBST) treatment group, or a no-treatment control group. Pain scores were analyzed pretreatment and posttreatment to determine group and within-subjects treatment effects. Results demonstrated that, in terms of a self-reported pain score, all three treatment groups had significantly decreased pain scores from pretreatment to posttreatment, while the no-treatment group did not. Moreover, patients in the biofeedback group were the most significantly improved compared to the no-treatment group. Finally, participants in the three treatment groups displayed significant improvement in mood states.

Temporomandibular disorders. 2. Non-surgical treatment

There are many treatment modalities for temporomandibular disorders (TMD), most of which are effective in controlling symptoms, at least in the short term. The non-surgical treatment of temporomandibular disorders continues to be the most effective way of managing over 80 per cent of patients who present with symptoms of temporomandibular pain and dysfunction. In this, the second article in the series, a general overview of the current non-surgical treatment strategies for TMD will be presented.

Negative affectivity, somatic complaints, and symptoms of temporomandibular disorders

This study examined the relationship between trait anxiety, subjective somatic symptoms, and pain associated with temporomandibular disorders (TMD) in a combined cross-sectional and prospective study. Compared with the initial measurements, a significant reduction in anxiety and pain was observed in the follow-up phase (two years after evaluation and therapy). No change in general somatic complaints was found. In both the initial phase and the follow-up phase, a consistent relationship between anxiety, somatic complaints, and TMD-related pain was demonstrated. The results are in agreement with a conceptualization of negative affectivity (e.g., anxiety, distress, tension) as a general dimension of somatopsychic distress. The best predictors of later TMD pain were general somatic complaints, followed by initial pain, and trait anxiety. Significant moderate correlations between anxiety, somatic complaints, and response to muscle palpation (feelings of tenderness) were also found. It is concluded that studies of TMD should incorporate measures of negative affectivity and general somatic complaints because these factors are important predictors of TMD pain, response to treatment, and chronicity.

Tinnitus: evaluation of biofeedback and stomatognathic treatment

Thirty-two patients with disabling tinnitus received stomatognathic treatment and biofeedback therapy according to a cross-over design. The evaluation of treatment outcomes showed some improvements at the group level: decrease of tinnitus intensity, mood improvement and reduction of clinical signs of dysfunction in the masticatory system. Qualitative observations indicated numerous positive changes in patients' emotional and cognitive orientation vis à vis tinnitus. Some possible predictors of positive treatment outcome were observed: comparatively low severity of tinnitus, normal hearing or compensated hearing loss, occlusal interferences, jaw fatigue, diurnal bruxism and fluctuations in tinnitus intensity. Left-sided tinnitus seemed to be a negative predictor of stomatognathic and biofeedback treatment outcome. Consequently, stomatognathic and biofeedback treatment seem to have some positive effects on subgroups of tinnitus patients.

Technological methods in the diagnosis and treatment of temporomandibular disorders

Although there have been numerous technological devices introduced for the diagnosis and treatment of temporomandibular disorders, many are either ineffective or are research tools without direct clinical application. This article reviews the various modalities and makes recommendations regarding their effectiveness based on the available clinical and scientific evidence.

Physical medicine procedures affect temporomandibular disorders: a review

This article reviews the literature on the effectiveness of physical medicine procedures for treatment of temporomandibular disorders (TMD). Brief descriptions of some commonly used dental appliances, and pharmacological and surgical treatment methods are provided.

Devices for the diagnosis and treatment of temporomandibular disorders. Part III: Thermography, ultrasound, electrical stimulation, and electromyographic biofeedback

This last article in the three-part series on devices for the diagnosis and treatment of temporomandibular disorders (TMD) compared the claimed diagnostic usefulness of thermography with the present scientific evidence. In a similar manner, the therapeutic efficacy of ultrasound, electrical stimulation, and electromyographic biofeedback was also reviewed. This evaluation concluded that the application of thermography to the diagnosis of TMD is limited by variations within and among subjects and by intrinsic problems with controls of the test environment. It also concluded that evidence that therapeutic ultrasound alone is useful for the treatment of TMD is lacking, that positive clinical results of electrical stimulation may not be due to specific therapeutic effects, and that it is doubtful that the use of electrical stimulation devices can produce a position of the mandible that has any diagnostic or therapeutic significance. There is evidence, however, that relaxation training, assisted by EMG biofeedback, can reduce daytime muscle activity.

Electromyographic biofeedback and rest position training of masticatory muscles in myofascial pain-dysfunction patients

Twenty-four women outpatients with myofascial pain-dysfunction were divided into three groups of eight. All received bilateral masseter electromyographic biofeedback training. One group received biofeedback only; one group received additional instructions and modeling to place their jaw in the "rest" position; and one group was given a prosthetic guide that spaced the incisors 6.8 mm apart. Two 15-minute training sessions were conducted at a 1-week interval, with posttreatment assessment 2 weeks later. The instruction and prosthesis groups obtained significantly greater electromyographic reductions in masseter activity and increases in mandibular range of motion compared with the biofeedback-only group. Subjects with pain obtained a significant reduction in therapist and self-report pain ratings. The results suggest that short-term biofeedback treatment may be meaningfully augmented by procedures that place the mandible in the rest position.

Electromyographic studies of craniomandibular disorders: a review of the literature

Craniomandibular disorders have been investigated from many points of view, structurally and functionally. To evaluate the behaviour of the masticatory muscles, electromyography (EMG) has been widely used and the studies have emanated from many different paradigms. The purpose of this paper is to review articles in which EMG has been used to study symptomatic subjects. Findings from sleep studies and basic laboratory studies seem to support the hypothesis of a correlation between masticatory muscle hyperactivity and symptoms. Experimentally induced stress studies consistently show an increased activity in symptomatic subjects. Investigations of motor pauses, the often lengthened silent period, are summarized and discussed. Several different treatment strategies, particularly splints and biofeedback, have been evaluated using EMG, indicating a normalization, but controlled outcome studies are sparse. The use of EMG has thus substantially increased our knowledge of dysfunction of the masticatory system.

Stress as a factor in muscle and temporomandibular joint pain

Stress-induced muscle hyperactivity has been proposed as a major aetiological factor in the production of pain in the muscles of mastication and the temporomandibular joints. In the present study, a total of fifty-two patients with joint or muscle pain were evaluated for stress with the Derogatis Stress Profile (DSP). The muscle pain group (n = 24) had higher clinician ratings of psychological factors, stress and chronicity. The muscle-pain group also had higher Environmental Stress scores on the DSP, more intense pain, and more activity impairment than the joint-pain group (n = 28). The results of multiple regression analysis suggest an association between pain, depression, and impairment of activity in the muscle-pain group but not in the joint-pain group. The overall results further suggest that muscle pain develops at 'normal' levels of stress.

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.

Stress-induced muscular activity in mandibular dysfunction: effects of biofeedback training

Surface electromyographic (EMG) recordings from the left and right masseteric areas during physical and psychological induced stress were obtained from 20 patients with mandibular dysfunction and 20 healthy controls. Integrated electromyographic activity was not significantly different for the two sides but was higher for patients than for controls during both stress and relaxation. Anxiety level, as measured with the Taylor Manifest Anxiety Scale, was higher for patients. Biofeedback treatment for the patients resulted in significantly reduced signs and symptoms of mandibular dysfunction. When the test procedures were repeated, the controls had not changed in their electromyographic responses during stress, whereas the patients showed a significant decrease in this respect. The results obtained are discussed in terms of a systems-oriented etiological concept.

Treatment of mandibular dysfunction: the clinical usefulness of biofeedback in relation to splint therapy

The long-term treatment effects of biofeedback and occlusal splints on mandibular dysfunction were compared. Thirty female patients were randomly divided into two treatment groups. One group had full coverage splints, the other group received biofeedback training. At the re-examinations 1 and 12 months after completion of therapy, the subjective and clinical symptoms were significantly reduced in both groups. No significant differences between the groups were found. A stepwise analysis of regression indicated that biofeedback training may be a useful alternative to splint therapy in cases where night time bruxing is not the dominating feature.

Clinical and electromyographic effects of biofeedback training in mandibular dysfunction

Twenty patients with mandibular dysfunction, 10 acute and 10 chronic, were trained with electromyographic biofeedback from either m. masseter or m. frontalis area. The electromyographic activity in both muscle areas were recorded during six training sessions. The mean electromyographic activity decreased significantly within the sessions for both muscle areas, progressively more often for the m. masseter area. The activity did not decrease significantly between sessions for any muscle area. The clinical and subjective symptoms of mandibular dysfunction improved significantly after the training. No differences, electromyographically or clinically, among acute, chronic, m. masseter area, or m. frontalis area feedback patients could be observed. No correlation between decrease in electromyographic activity and symptoms could be established. Since a simplistic neuromuscular learning model for biofeedback training gains little support from these results, alternative views are discussed.

Temporomandibular joint disfunction syndrome and myofascial pain dysfunction syndrome: a critical review

Temporomandibular joint (TMJ) dysfunction syndrome and myofascial pain dysfunction (MPD) syndrome have been primarily viewed as dental problems and have only recently received close attention by psychologists. The literature reviewed in the present paper reveals that a substantial portion of the population is affected by these disorders. There is, however, a great deal of confusion that exists in relation to the aetiology and treatment of these syndromes. In an attempt to clarify the current understanding of these disorders, the present review first presents a discussion of the symptoms which comprise each of these syndromes and the proposed physiological mechanisms associated with each symptom. Next, the aetiological theories for each of these syndromes are reviewed and critically evaluated. Treatments which have been derived from the theoretical models are then discussed. Finally, methodological considerations involving classification, assessment and treatment issues are presented and future research needs are outlined.

Factors associated with successful outcome from behavioral therapy for chronic temporomandibular joint (TMJ) pain

A total of 42 chronic temporomandibular joint pain patients completed behavioral therapy for their pain. The role of clinical, sociodemographic, and psychosocial factors was examined in relation to treatment outcome (immediately following treatment and at 2-yr follow-up). Psychosocial factors were better predictors of treatment outcome than clinical and demographic factors. Patients who had the most successful outcomes (both short- and long-term) were more motivated and less depressed than other patients and were internal with respect to their health locus of control.

Evaluation of occlusal splint therapy and relaxation procedures in patients with temporomandibular disorders

Twenty-four patients were selected to participate in this study. Twelve patients were randomly selected to receive occlusal splint therapy and the other 12 to receive a simplified relaxation therapy technique. Observable pain scores, maximum comfortable interincisal distance, and maximum interincisal distances were recorded for each group before and after treatment. The occlusal splint group showed a significant decrease in total mean observable pain scores (decrease score of 10.5, t = 3.124; P less than 0.1). The relaxation group showed no significant decrease in total mean observable pain scores (decrease score of 1.8, t = 0.888; P = ns). The occlusal splint group showed a significant increase in the mean maximum comfortable opening (an increase of 12.4 mm, t = 5.085; P less than .01). The relaxation group showed no significant increase in the mean maximum comfortable opening (an increase of 2.3 mm, t = 0.734; P = ns). The occlusal splint group showed a significant increase in the mean maximum opening (an increase of 6.0 mm, t = 2.471; P less than .05). The relaxation group showed no increase in the mean maximum opening (decrease of 0.7 mm, t = 0.343; P = ns). This study suggests that occlusal splint therapy is a more effective treatment for the pain, tenderness, and limited mandibular opening associated with temporomandibular disorders than relaxation therapy. In this study, the relaxation technique used had no significant effect on the patients' pain, tenderness, or limited opening.

Assessment and treatment of stress in myofascial pain-dysfunction syndrome: a model for analysis

Myofascial pain dysfunction (MPD) syndrome has received widespread attention in the dental and psychological literature. The present paper considers issues concerning a stress-related muscular hyperactivity theory of MPD syndrome. A review of the empirical evidence as well as methodological problems evident in these studies has been noted. In addition, definition aspects of stress and a conceptual model of stress in clinical use is presented. A functional analysis of the problem components will help determine a proper treatment protocol for patients suffering from stress-related myofascial pain. A discussion of the conceptual model for assessment and treatment purposes is presented and its implications for future research noted.

The comparative efficacy of relaxation training and masseter EMG feedback in the treatment of TMJ dysfunction

The present series of single case studies was designed to evaluate the comparative efficacy of masseter EMG feedback with progressive relaxation training in the treatment of TMJ dysfunction. Study 1 employed a multiple baseline design across the symptoms of jaw pain, jaw tension and shoulder pain in a patient with chronic TMJ problems. The results indicated that relaxation training was the treatment responsible for improvements in subjective ratings of jaw pain and tension, whereas masseter EMG feedback provided little additional benefit. Trapezius EMG feedback was necessary to provide improvements in ratings of shoulder pain. Study 2 consisted of four single case designs in which masseter EMG feedback and relaxation training were compared with four TMJ patients. Results indicated that relaxation produced clear improvements in pain and tension ratings for two patients, a combination of EMG feedback and relaxation training resulted in slight improvements in one patient, and neither treatment procedure was effective for the final patient. The possibility of wide-scale application of relaxation training with TMJ patients and the need for further controlled research of masseter EMG feedback were discussed.

Comparison of effects of electromyographic biofeedback and occlusal splint therapy on mandibular dysfunction

In order to evaluate and compare the effects of biofeedback and occlusal splint therapy on mandibular dysfunction, 30 patients were randomly divided into two treatment groups. The patients were women aged 20--40 years without any obvious organic reasons for their symptoms. There were no significant differences between the two groups before the start of treatment in respect of signs and symptoms of mandibular dysfunction. One group used full coverage splints at night for 6 weeks. The other group received biofeedback training up to six times, 30 min per session. One month after completion of the therapy the patients were re-examined. Both groups showed a significant reduction in symptoms, both subjectively and clinically. No significant differences between the groups were found. The two treatments were thus equally effective in the short-term perspective in patients with signs and symptoms of mandibular dysfunction.

Myofascial pain-dysfunction syndrome: a psychobiological perspective

Myofascial pain-dysfunction (MPD) syndrome is a muscle-contraction headache-like pain of the face. In the past this has also been called temporomandibular joint syndrome. This syndrome is thought to be, in part, a stress-related pain. This paper discusses and evaluates the following topics: (1) patient characteristics, (2) etiological hypotheses, (3) experimental models of the syndrome, (4) psychological characteristics of the patients, (5) psychophysiological characteristics of the patients, and (6) relaxation therapies. Future research is also discussed.

Primary fibromyalgia (fibrositis): clinical study of 50 patients with matched normal controls

Detailed clinical study of 50 patients with primary fibromyalgia and 50 normal matched controls has shown a characteristic syndrome. Primary fibromyalgia patients are usually females, aged 25-40 yr, who complain of diffuse musculoskeletal aches, pains or stiffness associated with tiredness, anxiety, poor sleep, headaches, irritable bowel syndrome, subjective swelling in the articular and periarticular areas and numbness. Physical examination is characterized by presence of multiple tender points at specific sites and absence of joint swelling. Symptoms are influenced by weather and activities, as well as by time of day(worse in the morning and the evening). In contrast, symptoms of psychogenic rheumatism patients have little fluctuation, if any, and are modulated by emotional rather than physical factors. In psychogenic rheumatism, there is diffuse tenderness rather than tender points at specific sites. Laboratory tests and roentgenologic findings in primary fibromyalgia are normal or negative. Primary fibromyalgia should be suspected by the presence of its own characteristic features, and not diagnosed just by the absence of other recognizable conditions. This study has also shown that primary fibromyalgia is a poorly recognized condition. Patients were usually seen by many physicians who failed to provide a definite diagnosis despite frequent unnecessary investigations. A guideline for diagnosis of primary fibromyalgia, based upon our observations, is suggested. Management is usually gratifying in these frustrated patients. The most important aspects are a definite diagnosis, explanation of the various possible mechanisms responsible for the symptoms, and reassurance regarding the benign nature of this condition. A combination of reassurance, nonsteroidal antiinflammatory drugs, good sleep, local tender point injections, and various modes of physical therapy is successful in most cases.

Factors associated with nocturnal bruxism and its treatment

Using a single-subject design, two methods of treating nocturnal bruxism were evaluated. Neither technique was successful; both resulted in a rebound effect when treatment was stopped. In addition, the role of anxiety in bruxing behavior was evaluated. Contrary to most theoretical beliefs, bruxing resulting from anxiety was not as important as "anticipatory" anxiety resulting in bruxing.

Treatment of the myofascial pain-dysfunction syndrome: psychological aspects

Myofascial pain-dysfunction syndrome is a stress-related disorder that involves muscle hyperactivity. Psychological treatments should: reduce muscle tension by relaxation procedures, modify the psychological antecedents to the muscle tension, and modify the psychological consequences to the muscle hyperactivity. The scope of the treatment for the myofascial pain-dysfunction syndrome should be commensurate with the scope of the problem. Patients with brief transient pain, usually associated with discrete problems, should have commensurate, brief, limited interventions, such as a relaxation therapy practiced at home via a tape recording. Patients with long-term problems should have commensurate, longer, more extensive interventions that perhaps include modifying the behavior, the antecedents, and the consequences. These issues may be those that predict failure of treatment by the dentist who uses an occlusal therapy as well as the psychologist who uses a relaxation therapy.

Myofascial pain of the temporomandibular joint: a review of the behavioral-relaxation therapies

This paper reviews the behavioral-relaxation treatments of myofascial pain-dysfunction syndrome. The evidence indicates that this pain (located around the oral cavity) is due to muscle hyperactivity, most commonly of the lateral pterygoids. Research concerning relaxation techniques (i.e. progressive muscle relaxation and electromyographic feedback) has indicated the following: (a) in analogue research, normal healthy controls can learn to relax their muscles of mastication profoundly even during stress, and (b) in case reports, relaxation treatments are helpful clinical interventions, especially for pain patients who are not depressed, and who have not had the pain for more than a few years. Well controlled research is the next, essential step.

The use of temperature biofeedback in the treatment of chronic pain due to causalgia

A patient with chronic pain due to a reflex sympathetic dystrophy in his hand and arm was successfully treated with temperature biofeedback after several months of conservative standard medical care brought little relief. Over the 18 treatment sessions the patient learned to emit a reliable handwarming response of 1 to 1.5 degrees C. Coincident with his learning, the pain in his hand and arm decreased markedly and remained absent at 1-year follow-up.

Frustration and temporomandibular joint pain

The significance of frustration as a cause of temporomandibular joint pain is investigated through the use of bilateral electromyographic recording. Interpretation of both parametric and nonparametric data indicates the lack of relationship. The need for careful controls and the problems of psychologizing are discussed.