Postural activity in subjects with functional disorders of the chewing apparatus.
TL;DR: The individual variation of the electromyographic findings pointed to a differentiated etiology more than to a general increase of activity for emotional reasons, as its location differed among patients and was limited to single muscles in most cases.
Abstract: — In 39 patients with functional disorders of the temporomandibular joint and the muscles of mastication and in 45 dental students without such disorders, the activity in the temporal and masseter muscles was recorded with the subjects seated upright and the mandible at rest. On the average, the level of postural activity in the patients was significantly stronger than in the control group. The increase was not a general trait including all muscles under study, as its location differed among patients and was limited to single muscles in most cases. In the temporal muscles, increased activity was associated with tenderness by palpation. Strong postural activity in the masseter muscles was associated with pain in the cheek and tenderness of the deep part of the muscle. The individual variation of the electromyographic findings pointed to a differentiated etiology more than to a general increase of activity for emotional reasons.
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TL;DR: It is suggested that the "dysfunction" that is characteristic of several types of chronic musculoskeletal pain is a normal protective adaptation and is not a cause of pain.
Abstract: Articles describing motor function in five chronic musculoskeletal pain conditions (temporomandibular disorders, muscle tension headache, fibromyalgia, chronic lower back pain, and postexercise mus...
986 citations
Journal Article•
TL;DR: The literature in which craniofacial muscle pain has been induced by experimental techniques in animals and human volunteers and in which the effects on somatosensory and motor function have been assessed under standardized conditions is reviewed.
Abstract: Epidemiologic surveys of temporomandibular disorders (TMD) have demonstrated that a considerable proportion of the population--up to 5% or 6%--will experience persistent pain severe enough to seek treatment. Unfortunately, the current diagnostic classification of craniofacial muscle pain is based on descriptions of signs and symptoms rather than on knowledge of pain mechanisms. Furthermore, the pathophysiology and etiology of craniofacial muscle pain are not known in sufficient detail to allow causal treatment. Many hypotheses have been proposed to explain cause-effect relationships; however, it is still uncertain what may be the cause of muscle pain and what is the effect of muscle pain. This article reviews the literature in which craniofacial muscle pain has been induced by experimental techniques in animals and human volunteers and in which the effects on somatosensory and motor function have been assessed under standardized conditions. This information is compared to the clinical correlates, which can be derived from the numerous cross-sectional studies in patients with craniofacial muscle pain. The experimental literature clearly indicates that muscle pain has significant effects on both somatosensory and craniofacial motor function. Typical somatosensory manifestations of experimental muscle pain are referred pain and increased sensitivity of homotopic areas. The craniofacial motor function is inhibited mainly during experimental muscle pain, but phase-dependent excitation is also found during mastication to reduce the amplitude and velocity of jaw movements. The underlying neurobiologic mechanisms probably involve varying combinations of sensitization of peripheral afferents, hyperexcitability of central neurons, and imbalance in descending pain modulatory systems. Reflex circuits in the brain stem seem important for the adjustment of sensorimotor function in the presence of craniofacial pain. Changes in somatosensory and motor function may therefore be viewed as consequences of pain and not factors leading to pain. Implications for the diagnosis and management of persistent muscle pain are discussed from this perspective.
288 citations
TL;DR: It is concluded that patients with osseointegrated oral implant bridges have a masticatory muscle function equal to or approaching that of patients with natural teeth, or with tooth-supported bridges, with the same number of chewing units as the OIB-patients.
Abstract: The function of the masticatory system of 13 women, aged 42-59 years, with osseointegrated oral implant bridges (OIB) made within the last seven years was compared with that of 10 matched dentate controls by means of a questionnaire, clinical examination, bite force measurements and electromyographic recordings of biting and of postural muscle activity. Both groups were satisfied with their masticatory capacity according to the questionnaire. The clinically determined state of the masticatory system, as judged from the clinical dysfunction index, was normal in both groups. Three levels of bite force 1) gentle biting, 2) biting as when chewing and 3) maximal biting, were recorded with a bite force apparatus and electromyographically. There was no statistically significant difference between the groups at any level of bite force for any of the methods of registration. Nor was there any difference of the two groups in the activity of the masticatory muscles with the mandible in the postural position. It is concluded that patients with osseointegrated oral implant bridges have a masticatory muscle function equal to or approaching that of patients with natural teeth, or with tooth-supported bridges, with the same number of chewing units as the OIB-patients.
181 citations
TL;DR: Clinically, the determination of the presence or absence of TMD does not appear to be enhanced by the use of SEMG, but the modality may be useful in a meticulously controlled research setting.
Abstract: Background This article presents a comprehensive review of the recent literature regarding the scientific support for the use of surface electromyography (SEMG) in diagnosing and treating temporomandibular disorders (TMDs). Types of Studies Reviewed The authors conducted a Medline search involving human studies using the key words “surface electromyography or electromyography” and “masticatory muscles or temporomandibular disorders or craniomandibular disorders.” They also reviewed relevant articles regarding the clinical usefulness of SEMG based on reliability, validity, sensitivity and specificity, as well as additional references included in some of the articles. Results The clinical use of SEMG in the diagnosis and treatment of TMD is of limited value when one considers reliability, validity, sensitivity and specificity as measurement standards. SEMG does not appear to contribute any additional information beyond what can be obtained from the patient history, clinical examination and, if needed, appropriate imaging. Conclusions Clinically, the determination of the presence or absence of TMD does not appear to be enhanced by the use of SEMG. However, the modality may be useful in a meticulously controlled research setting. Clinical Implications SEMG has limited value in the detection or management of TMD and in some instances may lead to unnecessary dental therapy as a solution for those disorders.
144 citations
TL;DR: Technology advances in signal detection and processing have improved the quality of the information extracted from the surface EMG and furthered the understanding of the anatomy and physiology of the stomatognathic apparatus.
Abstract: Surface electromyography (EMG) allows the non-invasive investigation of the bioelectrical phenomena of muscular contraction. The clinical application of surface EMG recordings has been long debated. This paper reviews the main limitations and the current applications of the surface EMG in the investigation of jaw elevator muscles. Methodological factors associated with the recording of the surface EMG may reduce the reliability and sensitivity of this technique and may have been the cause of controversial results reported in different studies. Despite these problems, several clinical applications of surface EMG in jaw muscles are promising. Moreover, technological advances in signal detection and processing have improved the quality of the information extracted from the surface EMG and furthered our understanding of the anatomy and physiology of the stomatognathic apparatus.
136 citations
References
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TL;DR: According to the psychophysiologic theory, masticatory muscle spasm is the primary factor in myofascial pain-dysfunction syndrome as mentioned in this paper, and emotional rather than mechanical factors are the prime etiologic agents in stimulating chronic oral habits that produce muscle fatigue.
Abstract: According to the psychophysiologic theory, masticatory muscle spasm is the primary factor in the myofascial pain-dysfunction syndrome. Emotional, rather than mechanical, factors are the prime etiologic agents in stimulating chronic oral habits that produce muscle fatigue.
716 citations
TL;DR: The myofascial Genesis of Pain this article is a well-known work in the field of pain management, which is also related to our work, but different in many ways.
Abstract: (1952). The Myofascial Genesis of Pain. Postgraduate Medicine: Vol. 11, No. 5, pp. 425-434.
429 citations
TL;DR: The occlusal stability in centric relation was found to be of extreme importance for muscle harmony during swallowing, and electromyographic evidence of muscle balance in rest position could be obtained in more than one-half of the patients in spite of Occlusal interference and temporomandibular joint pain.
Abstract: The relationship between occlusal disharmony and pain in the temporomandibular joint and adjacent muscles was tested clinically and electromyographically before and after occlusal adjustment on 32 patients. Various degrees of bruxism associated with psychic tension and occlusal interferences were observed in all of the patients. Clinically, all patients experienced relief of the pain and discomfort after complete occlusal adjustment. Electromyographically, a harmonious and well-synchronized contraction pattern of the temporal and masseter muscles was recorded after the adjustment. Any type of occlusal interference was found to trigger muscle spasms and pain, but the most consistent and significant interference was a discrepancy between centric relation and centric occlusion. The muscle disharmony was displayed electromyographically mainly in swallowing. The second most significant occlusal disharmony was balancing side interference. The balancing side contact had to be lighter than the working side contacts to establish a harmonious masticatory pattern. The patients' symptoms subsided without altering the vertical dimension. A close correlation was observed between the clinical and electromyographic recordings of occlusal interferences and muscle disharmony. However, electromyographic evidence of muscle balance in rest position could be obtained in more than one-half of the patients in spite of occlusal interference and temporomandibular joint pain. Masticatory contacts were seldom observed posterior to centric occlusion. However, the occlusal contacts in swallowing apparently occurred between centric occlusion and centric relation. The occlusal stability in centric relation was found to be of extreme importance for muscle harmony during swallowing. Rest position determined by conventional clinical methods did not always correspond to minimal, harmonious muscle activity electromyographically. A slight opening from the clinically determined rest position often facilitated the recording of an even, minimal contraction of the temporal and masseter muscles. The mandible could be opened from this position about 1/2 inch further (a resting range) without eliciting any increased muscle activity from these muscles.
219 citations
TL;DR: Reasonable grounds exist for asserting that there is a significant relationship of psychological factors to nonorganic TMJ dysfunction, that these factors can be treated, and that this treatment results in relief of physical symptoms as well.
Abstract: Reasonable grounds exist for asserting that there is a significant relationship of psychological factors to nonorganic TMJ dysfunction, that these factors can be treated, and that this treatment results in relief of physical symptoms as well.
146 citations