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PubMedDate not supplied

From bite to mind: TMD--a personal and literature review.

PURPOSE: The purpose of this study was to present a personal view of the development of prevailing opinions about temporomandibular disorders (TMD) during the last half century from a mechanistic to a psychosomatic concept. It also presents some hypotheses concerning: (1) the role of stress in the etiology of human oral parafunctions and its relationship to oral stereotypies in domestic animals; and (2) the pathogenetic mechanisms of masticatory muscle pain. MATERIALS AND METHODS: The basis for this article was a review of personal experiences derived from clinical and research work with TMD patients. Studies of both older and more recent literature on TMD and related disorders--especially in the fields of stress research, psychosocial medicine, occupational medicine, and etiology--were also used. RESULTS: A clear line is found in the development of the ideas on etiology, pathogenesis, and therapy of TMD, from the mechanistic attitude of Costen syndrome through the introduction of psychologic and psychophysical theories by the Columbia and Chicago schools to the now increasingly accepted biopsychosocial concept and the view of refractory TMD as a chronic pain condition. CONCLUSION: The formerly dominant bite-centered therapies--including intraoral appliances, the effects of which still are unexplained--appear to be increasingly banished to the domain of placebo Hence, to an ever-increasing extent occlusal treatments are replaced by physiotherapy and cognitive behavior therapy. The presented hypotheses may have implications for the understanding of the origin of oral parafunction and masticatory muscle pain.

Animals↗
PubMed2003

Longitudinal results of mandibular distraction osteogenesis in hemifacial microsomia.

The aim of this study was to evaluate mandibular distraction therapy by three-dimensional (3-D) computed tomography (CT) imaging so as to be able to improve the treatment results. The study group consisted of eight children (3 male and 5 female) with hemifacial microsomia. For each child, CT scans of the head were available (Pro Speed S Fast Spiral scanner; General Electric). Longitudinal measurements of the mandible, bony and soft tissue 3-D reconstructions, and masticatory muscles were demonstrated. Three-dimensional CT scans provide important data concerning the results of mandibular distraction therapy and should be used in treatment evaluation. In some patients and for some muscles only, a small increase in the volume of the affected side of the masticatory muscles in comparison to the normal side was found 3 years after mandibular distraction. In around 50% of the cases, there seems to be a relapse occurring 1 year after distraction osteogenesis, and this relapse has a progressive character when seen 3 years after distraction osteogenesis in comparison to 15 weeks after distraction osteogenesis.

Adolescent↗
PubMed2006

Efficacy of physical therapy in the treatment of masticatory myofascial pain: a literature review.

The term temporomandibular disorders (TMD) is used to indicate a heterogeneous group of painful conditions involving masticatory apparatus and its related structures whose complicated etiology involves a number of diagnostic and taxonomical matters. The prevalence of TDM has remarkably increased in the last years, such that, at present, these clinical conditions represent the most frequent cause of orofacial pain in the general population: in particular, among these disorders, pathologies affecting masticatory muscles have a considerable clinical and epidemiological relevance. Due to the high prevalence of masticatory myofascial pain, as well as the taxonomical issue that emerges from literature data, the wide range of treatment modalities proposed for this condition seems to be justifiable. Among the various therapeutic solutions employed in the management of masticatory myofascial pain, it is interesting to focus on the efficacy of the different kinds of physical therapy. In fact, due to the difficulties related with the attempt to isolate a sole etiological factor, at the beginning should be carried out reversible and noninvasive interventions: in these terms, the use of physical therapy seems to be reasonable. The aim of the present paper is to provide a critical review of the literature about the use of physical therapy approaches in relieving pain symptoms that often accompany masticatory muscles disorders. This study seems to suggest that the employ of physical therapy could be useful in the treatment of myogenous TDM, even though further studies are needed to assess the efficacy of this tool.

Humans↗
PubMed1989

Physiological identification and property of afferents from the masseter muscle to the caudal part of the trigeminal nucleus in rat.

The present study was to identify the physiological properties of the afferent fibers from the masseter muscle to the caudal part of the spinal trigeminal nucleus of rat using a microelectrode technique. When electrical stimulation was applied to the masseter muscle, the evoked potentials were recorded with a shorter latency (the S-response) or a longer latency (the L-response). The threshold current intensity of the S-response was lower than that of the L-response. There were statistical significant differences between the S-response and the L-response in latency and in threshold current intensity. Both the S- and L-responses could follow by stimulation of low frequencies (10 to 30 Hz), indicating that the evoked responses were the component of the secondary neuron activities. On the anatomical and physiological assumption, the conduction velocities of the S- and the L-responses were calculated and they were in the range of that of A-delta fibers. We also observed that both the S- and the L-responses could not follow high frequency stimulation of the masseter muscle. This effect may reflect the phenomenon of fatigue in the finely myelinated fibers or polymodal nociceptors. Thus, the present study suggested the involvement of the afferents from the masseter muscle to the spinal trigeminal nucleus in the transmission and the relay of the masticatory muscle pain.

Afferent Pathways↗
PubMed2000

Masticatory and skeletal muscle myositis in canine leishmaniasis (Leishmania infantum).

Twenty-four dogs with a parasitologically and serologically established diagnosis of leishmaniasis were studied to investigate the atrophy of the masticatory muscles which commonly occurs in this disease, and to compare the lesions in the masticatory muscles with those in the cranial tibial muscles. The 24 animals were divided into three groups of eight, group A dogs with no muscular atrophy, group B dogs with different degrees of atrophy in the masticatory and skeletal muscles, and group C dogs with similar degrees of atrophy in the masticatory and skeletal muscles. Increased activities of creatine phosphokinase and lactate dehydrogenase were recorded in only some of the dogs in groups B and C, but there were no significant differences between the mean activities in the three groups. Electromyographic changes indicating myopathy and involving both the temporalis and cranial tibial muscles, were observed in two of the dogs in group A, seven of those in group B, and in all the dogs in group C. Muscle histopathology revealed a variable degree of muscle fibre necrosis and atrophy, mononuclear infiltrates and neutrophilic vasculitis in all the dogs except two in group A. Leishmanial amastigotes were found within macrophages and myofibres in 16 of the dogs, some in each group. IgG immune complexes were detected in muscle samples, and circulating antibodies against myofibres were detected in serum samples from all the 24 dogs.

Animals↗
PubMed1992

Sex differences in signs and symptoms from masticatory and other muscles in 19-year-old individuals.

Pain and tenderness of masticatory muscles are often related to muscle tenderness elsewhere in the body. It has been shown that women are more prone to musculoskeletal disorders than men. We sought to determine whether sex differences of muscular symptoms were established by the age of 19. The subjects comprised 51 boys and girls who received a questionnaire regarding the function of their masticatory system, frequency of headache, and neck, shoulder and low back pain. Their masticatory system was examined, and neck and shoulders were palpated. For all variables in the questionnaire girls reported symptoms more often than the boys. Of the subjects 50% had tender chewing muscles upon palpation. Again the girls had the most. There was good correlation between reports of pain in one area as compared to others. The number of clinically tender neck and shoulder muscles correlated with the number of tender masticatory muscles. It was concluded that girls presented more muscular symptoms than boys.

Adult↗
PubMed2004

Effects of increased muscle mass on mouse sagittal suture morphology and mechanics.

The purpose of this study is to test predicted form-function relationships between cranial suture complexity and masticatory muscle mass and biomechanics in a mouse model. Specifically, to test the hypothesis that increased masticatory muscle mass increases sagittal suture complexity, we measured the fractal dimension (FD), temporalis mass, and temporalis bite force in myostatin-deficient (GDF8(-/-)) mice and wild-type CD-1 mice (all male, 6 months old). Myostatin is a negative regulator of muscle mass, and myostatin-deficient mice show a marked increase in muscle mass compared to normal mice. We predicted that increased sagittal suture complexity would decrease suture stiffness. The data presented here demonstrate that increased suture complexity (measured as FD) was observed in a hypermuscular mouse model (GDF8(-/-)) with significantly increased temporalis muscle mass and bite forces. Hypermuscular mice were also found to possess suture connective tissue that was less stiff (i.e., underwent more displacement before failure occurred) when loaded in tension. By decreasing stiffness, suture complexity apparently helps to dissipate mechanical loads within the cranium that are related to chewing. These results suggest that cranial suture connective tissue locally adapts to functional demands of the biomechanical suture environment. As such, cranial sutures provide a novel model for studies in connective tissue mechanotransduction.

Animals↗
PubMed1987

Signs and symptoms of mandibular dysfunction in patients with suspected oral galvanism.

Fifty-four consecutive patients were examined by means of a self-administered questionnaire with questions related to general health and subjective symptoms. In addition, a clinical stomatognathic evaluation was carried out including palpation of the temporomandibular joints (TMJ) and the masticatory muscles and functional analysis of occlusion and mandibular mobility. High frequencies of general diseases were reported. The dominant subjective symptom was headache (62%), which often appeared daily. Symptoms such as pain from the teeth, pain in the face/jaws, and burning sensations in the tongue or oral cavity all appeared in more than half of the sample. The patients were frequently aware of parafunctions such as clenching of the teeth and tongue press. None of the investigated persons were completely free of clinical signs of dysfunction. The most frequent clinical finding was palpation tenderness in the masticatory muscles (96%), generally located in the masseter, temporal, and lateral pterygoid muscles. In more than half of the material TMJ findings were recorded, and more than one-third had TMJ pain. In 35% mandibular mobility was reduced. Occlusal interferences on retrusion and on the mediotrusion side were frequent findings. Impaired general state of health and multiple signs and symptoms of mandibular dysfunction were thus frequent findings in these polysymptomatic patients. Three-fourths of the patients needed treatment for mandibular dysfunction, indicating that great consideration must be made for the functional status of the masticatory system in clinical evaluation of so-called 'oral galvanists'.

Adult↗
PubMed2005

The masticatory system--an overview.

Masticatory muscle physiology has been evaluated mostly from electromyographic recordings. However, electromyography coupled with jaw-tracking devices has provided much more information of the correlation between jaw movements and muscle activity. Knowledge of how the mandible moves during mastication has greatly influenced procedures in clinical dentistry. The aim of this overview is to give basic description of the classical studies of the physiology, function and neural control principles of the mastication. Mastication is the action of breaking down of food, preparatory to deglutition. This breaking-down action is highly organized complex of neuromuscular and digestive activities. The duration and forces developed in the power stroke vary within and between individuals and for the type of the food being chewed. It has been suggested that the observation of masticatory movements may be of diagnostic value for assessing disorders of the stomatognathic system, but there is not clear evidence to show significant differences. The action of masticatory muscles during chewing varies between subjects in amplitude, onset timing, and duration of the chewing cycle. Since tooth guidance has an enormous influence on muscle activity during chewing and swallowing, it is advisable to make restorations compatible with the functional movement patterns of the patient rather than expect the patterns of the mastication to adapt to the new made restorations.

Brain Stem↗
PubMed1991

[Clinical-experimental study of muscle activity of complete denture wearers with various prostheses before and after equilibration].

The present electromyographic investigations, which were carried out by patients with full dentures should show if the activity-situation of the masticatory muscles would change either using a new full denture without equilibration or using new full dentures with equilibration. Other questions were: Is it possible to classify the patients in such, who prefer the masseter muscles or the temporalis muscles during mastication? Exist a correlation between the preferred masticatory side and an increased activity of the same side masticatory muscles?

Adult↗
PubMed2005

Flexure deformation in temporomandibular joint disk displacement without reduction may predict treatment outcome.

To identify whether the direction of disk flexure deformation predicts the prognosis in cases of anterior disk displacement without reduction of painful temporomandibular joint (TMJ), the relationship between the direction of flexure, observed on pseudodynamic magnetic resonance (MR) images, and the outcome of conservative treatment using a flat occlusal splint was analysed in 40 female patients who perceived occasional or constant pain at unilateral TMJ with disk displacement without reduction. From the MR findings, 20 patients were classified as having upward flexure deformation of the disk and 20 as having downward flexure deformation. Patients' TMJ pain, masticatory muscle pain, amount of maximal mouth opening, and MR findings were evaluated before treatment. All patients were treated with a flat occlusal splint for 6 months. The patients' signs and symptoms were analysed statistically within each group before treatment and 3 and 6 months afterwards, and were also compared between the upward and downward flexure groups. There was no statistical difference between the groups before treatment, except in the amount of maximal mouth opening and the extent of disk displacement. The upward flexure group had persistent TMJ pain and tendency of delayed alleviation of masticatory muscle pain compared with the downward flexure group, although maximal opening gradually increased in both groups. Thus, the direction of the flexure in deformation of the disk, which can be observed only with pseudodynamic MR imaging, may predict the prognosis of painful disk displacement without reduction following treatment with a flat occlusal splint.

Adolescent↗
PubMed2002

A randomized clinical trial using research diagnostic criteria for temporomandibular disorders-axis II to target clinic cases for a tailored self-care TMD treatment program.

AIMS: To carry out a randomized clinical trial (RCT) contrasting usual conservative treatment of TMD by clinical TMD specialists with a structured self-care intervention, targeted to clinic cases independent of TMD physical diagnosis, who were reporting minimal levels of psychosocial dysfunction; the intervention was delivered by dental hygienists in lieu of usual treatment. METHODS: The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) was used to target subjects who exhibited minimal TMD-related psychosocial interference. Criteria for study inclusion were: (1) self-report of facial and/or masticatory muscle pain discomfort for which usual care was prescribed by the clinic TMD specialist; (2) RDC/TMD Axis II graded scale of chronic pain (GCP) score of 0, I, or II-Low. (3) Age 18 to 70 years. RESULTS: On 1-year follow-up, while both groups showed improvement in all clinical and self-report categories measured, patients in the tailored self-care treatment program compared to usual TMD treatment showed significantly; (a) decreased TMD pain, (b) decreased pain-related interference in activity; (c) reduced number of masticatory muscles painful; (d) fewer additional visits for TMD treatment. Groups were comparable with regard to measures of vertical range of motion. The self-care program was associated with consistent, but non-statistically significant, trends towards lower levels of depression and somatization. Ability to cope with TMD, knowledge concerning TMD and patient satisfaction was significantly enhanced for the self-care group. No participating patients experienced physical or personal adverse effects during the 1-year post-treatment follow-up period. CONCLUSION: Use of RDC/TMD psychosocial assessment criteria can contribute to successful clinical decision-making for the management of TMD.

Adult↗
PubMed1995

Effects of fatigue and chewing training on maximal bite force and endurance.

The purpose of the study was to evaluate the effects of chewing training on the strength and resistance to fatigue of the masticatory muscles. Twenty-five healthy adults were divided into an experimental group (7 men, 10 women) and a control group (4 men, 4 women). The experimental group chewed a special hard chewing gum one hour daily for 28 days. Maximal bite force and endurance were measured. The maximal bite force already showed a significant increase in the experimental group by the middle of the experimental period (p < 0.05), reached the highest values by the end of the training period (p < 0.001), and also remained at high levels 2 weeks after (p < 0.001). Subjects with weak initial maximal bite force values showed the highest increase in their strength after training (r = -0.66, p < 0.01). This type of training did not influence the endurance time during maximal clenching or the reduction in this endurance time after a dynamic fatigue test. No significant differences were found between the maximal bite force before and that after the fatigue test under either untrained or trained conditions. In the control group no significant differences were found between the recording sessions. In conclusion, 4 weeks training with a hard chewing gum seems to influence the functional capacity of the masticatory muscles and increase their strength.

Adult↗
PubMed1986

Comparison of tests for dysfunction of the stomatognathic system.

As part of a validating process, tests and indices for dysfunction of the temporomandibular joints and masticatory muscles were compared and correlated in 211 persons with an almost complete or complete natural dentition. Helkimo's Clinical Dysfunction Index (CDI), the Mandibular Dysfunction Symptoms (MDS) scale from the "Erweiterter Giessener Beschwerdebogen", the Modified Half-Minute (MHM) test and the palpation test for the stomatognathic system (PALP-test) were compared. The PALP-test had the highest internal consistency (coefficient alpha = 0.92) and the highest intercorrelation with the CDI. Furthermore, it was found that the PALP-test and the CDI probably yield the most realistic distribution of persons in the three classes no symptoms, mild to moderate and severe, and also show the highest percentage of absolute correspondence. The MDS-scale and MHM-test scores showed little dispersion and probably indicated too much or too little pathology. The correspondence between the last two measures is mainly due to an overrepresentation of the middle scoring class (mild to moderate indication of dysfunction of the temporomandibular joints and masticatory muscles). In screening procedures this can easily result in an overrepresentation of people with supposed pathology.

Facial Pain↗
PubMed1999

Does the sequence of onset of rigor mortis depend on the proportion of muscle fibre types and on intra-muscular glycogen content?

We examined the postmortem changes in the levels of ATP, glycogen and lactic acid in two masticatory muscles and three leg muscles of rats. The proportion of fibre types of the muscles was determined with NIH image software. The ATP levels in the white muscles did not decrease up to 1 h after death, and the ATP levels 1 and 2 h after death in the white muscles were higher than those in the red muscles with a single exception. The glycogen level at death and 1 h after death and the lactic acid level 1 h after death in masticatory muscles were lower than in the leg muscles. It is possible that the differences in the proportion of muscle fibre types and in glycogen level in muscles influences the postmortem change in ATP and lactic acid, which would accelerate or retard rigor mortis of the muscles.

Adenosine Triphosphate↗
PubMed1997

Identification of rat brainstem multisynaptic connections to the oral motor nuclei in the rat using pseudorabies virus. II. Facial muscle motor systems.

The present experiments continue our investigations of the higher order afferent systems controlling the orofacial musculature. Pseudorabies virus (PRV) was injected into the buccinator, platysma, posterior digastric, and zygomatic muscles in bilaterally sympathectomized rats. Injection volumes ranged from 6 to 12 microl with average titers of 7 x 10(8) pfu/ml and maximum survival times of 96 h. The labeling patterns and distributions were similar across the individual muscles and between muscle groups (perioral vs. posterior digastric), as well as in comparison to the results from previous masticatory muscle injections. Injections produced a predictable myotopic labeling pattern in the facial motor nucleus (Mo 7) and transneuronally in regions known to project directly to Mo 7 including the red nucleus, ventrolateral parabrachial region, principal trigeminal sensory nucleus, supratrigeminal area, and the parvicellular reticular formation. Maximum survival times revealed more distant connections from a variety of nuclear zones including the periaqueductal gray, laterodorsal and pedunculopontine tegmental areas, and the substantia nigra in the midbrain, ventromedial reticular regions including the gigantocellular region and pars alpha and ventralis in the pons and medulla, and the nucleus of the solitary tract, spinal trigeminal nucleus caudalis, paratrigeminal region, and paramedian field in the medulla. The similarity of the labeling patterns and distributions of the higher order afferents resulting from PRV facial and masticatory muscle injections identifies the neural circuits that may coordinate the activity of these muscle groups during oral motor behavior.

Animals↗
PubMed2004

Efficacy of tizanidine hydrochloride in the treatment of myofascial face pain.

AIM: The aim of the present investigation was to evaluate the usefulness of tizanidine hydrochloride in the treatment of myofascial pain of the masticatory muscles. METHODS: This work is a preliminary report of clinical experience with the use of tizanidine hydrochloride at the Section of Prosthetic Dentistry, Department of Neuroscience, University of Pisa, Pisa, Italy. During the period from January 2000 to March 2003, 145 patients were given Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I group I diagnosis of myofascial pain in the absence of any painful temporomandibular joint condition. Seventy-eight subjects agreed to suspend any kind of treatment they had undergone and to start assuming tizanidine hydrochloride (SIRDALUD) 4 mg/die per os (2 2- mg tablets a day, 1 in the morning and 1 after dinner) for 2 weeks. All underwent a clinical assessment according to RDC/TMD guidelines at baseline time and were re-evaluated at the end of the treatment period. RESULTS: At the end of the treatment period all patients had improved; 42/78 patients (53.8%) showed absence of clinical symptoms; 18/78 (23.1%) showed a good improvement, still presenting a low number of painful sites, but not satisfying RDC/TMD parameters for diagnosis of myofascial pain; 18/78 (23.1%) showed only a slight improvement, still presenting a high number of painful sites and satisfying RDC/TMD parameters for diagnosis of myofascial pain. CONCLUSION: Given the absence of papers on the use of tizanidine hydrochloride in the treatment of myofascial pain of the masticatory muscles, the present investigation could provide some preliminary data about its possible efficacy. Randomized and controlled clinical trials are needed to confirm these results.

Adult↗
PubMed1989

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.

Adult↗