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Results for “Masticatory Muscles”

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At least 1,135 records · Page 63Linked to original sources

PubMed1997

Prevention of temporomandibular disorder-related signs and symptoms in orthodontically treated adolescents. A 3-year follow-up of a prospective randomized trial.

Recommendations about the need for occlusal adjustment after malocclusion therapy are inconclusive. A total of 123 orthodontically treated healthy adolescents (88 girls, 35 boys; 14.8 +/- 1.7 years old) agreed to participate in the present study. The subjects were interviewed and examined for signs and symptoms related to temporomandibular disorder (TMD) and were randomly allocated to intervention (n = 63) and control (n = 60) groups. At base line, occlusal adjustment was carried out for the intervention group and repeated every 6 months thereafter as needed. Mock adjustments were performed for the control group. At the end of the 3rd year 118 subjects (96%) turned up for re-examination. The number of subjects with palpatory pain of the masticatory muscles, and with occlusal centric slides decreased significantly in the intervention group but not in the control group (P < 0.001). In conclusion, occlusal adjustment therapy may prevent the occurrence of TMD signs in orthodontically treated healthy adolescents.

Adolescent↗

PubMed2001

Oral jaw behaviors in TMD and bruxism: a comparison study by severity of bruxism.

The purpose of this study was to document the prevalence of oral jaw behaviors concomitant to bruxism in TMD+bruxing behavior patients and in nonbruxer controls. Clinical examination, questionnaires, and specific criteria to allocate patients to mild, moderate, and severe groups of TMD and bruxers were used. The sample consisted of 274 TMD+bruxing behavior patients and 52 control non-bruxing behavior groups evaluated at the Center for the Study of TMD. The mean age of the TMD+bruxing behavior group was about 33.11 years old (range 16.66, SD = 11.52) as compared to 34.90 years old (range 17-67, SD = 14.26) in the control group. Oral jaw behaviors were assessed in the mild, moderate, and severe TMD+bruxing groups, and in the corresponding control group. It was found that the prevalence of oral jaw behaviors was higher in the TMD+bruxing behavior group as compared to the control. Hence, concomitant oral jaw behaviors predominated in bruxers and increased with its severity. The data reinforce the need to assess TMD patients in terms of the presence of bruxism, its severity, and concomitant oral jaw habits. Such approach will enable the clinician to have better understanding about the role of these behaviors in TMD. Epidemiological data was also provided regarding jutting the jaw forward (a rarely-described oral jaw habit) in a relatively large sample of TMD+bruxing patients, suggesting a more clinical intervention in children and adolescents. This study is the first to document the prevalence of specific oral jaw habits in a relatively large sample of TMD+bruxing behavior classified by degree of severity. Results suggest that TMD+bruxing patients may present many other additional oral jaw habits which may concur to increase masticatory muscle activity thus leading to TMD signs and symptoms. Factors responsible for the increased frequency of oral jaw habits with the severity of bruxism behavior remain unknown and therefore further studies are needed.

Adolescent↗

PubMed1997

Headache and cranio-mandibular disorders during adolescence.

A clinical and epidemiological investigation was performed on 62 adolescents, 21 males and 41 females, with recurring headaches, in order to analyze the connections between the cephalalgia and the signs and symptoms of mandibular dysfunction. The anamnestic and objective data were reviewed with the aid of the Helkimo indices and compared to data on a control group of comparable age who were not headache sufferers. The most statistically significant signs encountered (p < 0.001) were: pain on palpation of masticatory muscles (61%), altered (43%) or reduced (27%) mandibular movement, preauricular tenderness (19%); the high incidence of parafunctions indicated the behavioral substrate. This pilot study reveals a link between the two pathologies and the need for early diagnosis, preventive identification of the subjects at risk and interdisciplinary cooperation.

Adolescent↗

PubMed1995

Tumor necrosis factor in synovial fluid of patients with temporomandibular disorders.

PURPOSE: To assess tumor necrosis factor (TNF) activity in synovial fluid from patients with temporomandibular disorders. PATIENTS AND METHODS: Tumor necrosis factor (TNF) activity in synovial fluid from 27 patients with temporomandibular disorders (TMDs) was studied using the MTT tetrazolium WEHI 164 clone 13 cell cytotoxicity assay. RESULTS: No detectable TNF levels were found in five patients with a masticatory muscle disorder, but elevated TNF levels were found in 5 of 11 patients with TMJ disc displacement, and in 9 of 11 patients with degenerative joint disease. CONCLUSION: The findings of biologically active TNF in the synovial fluid of these patients suggests that it may play a role in the pathogenesis of certain temporomandibular disorders.

Adolescent↗

PubMed1999

[A comprehensive study of the mechanical effects of the long-term and regular use of chewing gum].

The results of regular gum chewing (30 min 3 times a day after meals for 4 weeks) were assessed in 46 volunteers by the functional diagnosis methods. Chronometry of food chewing and arbitrary gum chewing for 30 min was carried out before the investigation. Daily duration of food chewing is about 33 min. During gum chewing, the number of masticatory strikes on the inert side is higher during the first 5 min and then levels. This leads to levelling of mechanical loading of the lateral parts of the jaws and of bioelectrical activity in the masticatory muscles proper. The gum is bit 3-5 times more often with frontal teeth than with lateral teeth. Regular use of chewing gum notably increases the blood supply to the periodontium, and the regulatory mechanisms fail to cope with it in periodontal diseases; this leads to venous congestion in the regional vascular system.

Adult↗

PubMed1994

Surgical versus nonsurgical treatment of unilateral dislocated low subcondylar fractures: a clinical study of 52 cases.

To compare open versus closed reduction of unilaterally dislocated low subcondylar fractures in adults, 101 consecutive dentulous patients were treated either by closed reduction with a median of 4 weeks of maxillomandibular fixation, or with a median of 6 weeks of maxillomandibular fixation after surgical repositioning and transosseous wiring of the dislocated condylar fragment. No selection of patients was done for either treatment. Fifty-two patients were seen at a median of 2 years postoperatively. Complications such as malocclusion, mandibular asymmetry, impaired masticatory function, and pain located to the affected joint or masticatory muscles were seen significantly more frequent in patients treated with closed reduction compared with those treated surgically (P = .005). Neither the degree of dislocation of the proximal fragment, concomitant mandibular fractures, nor the absence of posterior occlusal support seemed to influence the results.

Adolescent↗

PubMedDate not supplied

Combat and warfare in the early paleolithic and medically unexplained musculo-facial pain in 21st century war veterans and active-duty military personnel.

In a series of recent articles, we suggest that family dentists, military dentists and psychiatrists with expertise in posttraumatic stress disorder (especially in the Veterans Health Administration) are likely to see an increased number of patients with symptomatic jaw-clenching and early stages of tooth-grinding (Bracha et al., 2005). Returning warfighters and other returnees from military deployment may be especially at risk for high rates of clenching-induced masticatory muscle disorders at early stages of incisor grinding. The literature we have recently reviewed strongly supports the conclusion that clenching and grinding may primarily be a manifestation of experiencing extreme fear or severe chronic distress (respectively). We have recently reviewed the clinical and paleoanthropological literature and have noted that ancestral warfare and ancestral combat, in the early Paleolithic Environment of Evolutionary Adaptedness (EEA) may be a neglected factor explaining the conservation of the archaic trait of bite-muscle strengthening. We have hypothesized that among ancestral warriors, jaw clenching may have rapidly strengthened the two primary muscles involved in biting, the masseter muscles and the much larger temporalis muscles. The strengthening of these muscles may have served the purpose of enabling a stronger, deeper, and therefore more lethal, defensive bite for early Paleolithic humans. The neuroevolutionary perspective presented here may be novel to many dentists. However, it may be useful in patient education and in preventing progression from jaw-clenching to chronic facial pain.

Biological Evolution↗

PubMedDate not supplied

Light and scanning electron microscopic report of four fractured implants.

Although they are fortunately rare, implant fractures can cause significant problems for both clinicians and patients. The authors present a light and scanning electron microscopic study of four fractured implants in two patients. Both patients had parafunctional habits (bruxism), hypertrophic masticatory muscles, and wear of occlusal surfaces. The scanning electron microscopic study of the fractured surfaces of all four implants showed the presence of fatigue striations. Bending overload was probably created by a combination of parafunctional forces, bone resorption, posterior location of the implants, and implant diameter.

Aged↗

PubMed1998

Correlation between cervical spine and temporomandibular disorders.

Neuroanatomical interconnections and neurophysiological relationships between the orofacial area and the cervical spine have been documented earlier. The present single-blind study was aimed at screening possible correlations between clinical signs of temporomandibular disorders (TMD) and cervical spine disorders. Thirty-one consecutive patients with symptoms of TMD and 30 controls underwent a standardised clinical examination of the masticatory system, evaluating range of motion of the mandible, temporomandibular joint (TMJ) function and pain of the TMJ and masticatory muscles. Afterwards subjects were referred for clinical examination of the cervical spine, evaluating segmental limitations, tender points upon palpation of the muscles, hyperalgesia and hypermobility. The results indicated that segmental limitations (especially at the C0-C3 levels) and tender points (especially in the m. sternocleidomastoideus and m. trapezius) are significantly more present in patients than in controls. Hyperalgesia was present only in the patient group (12-16%).

Adolescent↗

PubMed1994

Effect of unilateral bite splint on mastication in the miniature pig.

Unilateral premature occlusal contacts are known to alter masticatory activity levels during clenching, but whether natural chewing is similarly affected is not known. The purpose of this study was to analyse the effects of a unilateral bite splint on mastication. Eleven experiments were carried out using three miniature pigs. Electromyography of the masticatory muscles and movements of the jaw were recorded during natural chewing before and after inserting a bite splint on the second and third deciduous premolars. In contrast to human clenching, the integrated activities of the jaw-closing muscles increased, especially on the contralateral side. The increases were mainly due to the prolongation of the burst durations. Jaw opening activity was increased as well. The frequency of mastication fell slightly and the animal preferred to chew food on the bite splint side. These results demonstrate the importance within the particular experimental conditions of the occlusal condition in regulating chewing behaviour.

Animals↗

PubMed1991

Jaw dystonia triggered by biting into hard food.

We report an unusual case of eating dystonia induced by attempts to bite into hard food and resulting in prolonged jaw opening spasms. Mastication was severely impeded. Simultaneous bilateral electromyogram (EMG) of the masticatory muscles during mastication of hard food showed an abnormal prolonged activity in the anterior digastrics with an abnormal cocontraction of these muscles during contraction of the jaw-closers and a prolonged inhibition of the jaw-closers until the hard bolus was softened. This action dystonia seems to be triggered when more than a certain pressure is exerted on the peridontal mechanoreceptors and could result from a defective central command control of their sensory inputs. Local injections of botulinum toxin had little effect.

Bite Force↗

PubMed2003

The efficacy of appliance therapy in patients with temporomandibular disorders of mainly myogenous origin. A randomized, controlled, short-term trial.

AIMS: To compare the short-term efficacy of treatment with a stabilization appliance compared with that of a non-occlusal, control appliance in patients with temporomandibular disorders (TMD) of mainly myogenous origin. METHODS: A randomized, controlled trial was performed with 60 patients suffering from myofascial pain. Patients were randomly assigned to a treatment or a control group. The treatment group was treated by means of a stabilization appliance and the control group by means of a non-occlusal appliance. Symptoms and signs were registered before and after 10 weeks of treatment. RESULTS: Improvement of overall subjective symptoms was reported in both groups, but significantly more often in the treatment group than in the control group (P = .000). The prevalence of daily or constant pain showed a significant reduction in the treatment group (P = .028) compared with the control group. There was a significant decrease in the number of tender masticatory muscles in the treatment group (P = .018) compared with the control group. CONCLUSION: The results of this short-term evaluation suggest that the stabilization appliance is more effective in alleviating symptoms and signs in patients with TMD of mainly myogenous origin than a control, non-occlusal appliance. The stabilization appliance can therefore be recommended for the therapy of these patients.

Adolescent↗

PubMed2001

Type A botulinum toxin in the treatment of chronic facial pain associated with temporo-mandibular dysfunction.

In an open-label study 41 patients suffering from the muscular form of temporo-mandibular dysfunction were treated with botulinum toxin type A injections into masticatory muscles (average of 200 U on each side) and followed for an average of 6.7 months. Eighty percent of patients improved by a mean reduction of 45% on a visual analogue pain scale. During the observation period, 17% of patients had to receive a second injection because of recurrent pain. Reversible speech and swallowing difficulties occurred in only 1 patient. These encouraging results need to be confirmed by a randomized controlled trial.

Botulinum Toxins, Type A↗

PubMed1975

The human mandible: lever or link?

The mammalian mandible, and in particular the human mandible, is generally thought to function as a lever during biting. This notion, however, has not gone unchallenged. Various workers have suggested that the mandible does not function as a lever, and they base this proposition on essentially two assertions: (1) the resultant of the forces produced by the masticatory muscles always passes through the bite point; (2) the condylar neck and/or the temporomandibular joint is unsuited to withstand reaction forces during biting. A review of the electromyographic data and of the properties of the tissues of the temporomandibular joint do not support the non-lever hypothesis of mandibular function. In addition, an analysis of the strength of the condylar neck demonstrates that this structure is strong enough to withstand the expected reaction force during lever action. Ordinarily the human mandible and the forces that act upon it are analyzed solely in the lateral projection. Moments are then usually analyzed about the mandibular condyle; however, some workers have advocated taking moments about other points, e.g., the instantaneous center of rotation. Obviously it makes no difference as to what point is chosen since the moments about any point during equilibrium conditions are equal to zero. It is also useful to analyze the forces acting on the mandible in the frontal projection, particularly during unilateral biting. The electromyographic data suggest that during powerful unilateral molar biting the resultant adductor muscle force is passing between the bite point and the balancing (non-biting side) condyle. Therefore, in order for this system to be in equilibrium there must be a reaction force acting on the balancing condyle. This suggests that reaction forces are larger on the balancing side than on the working side, and possibly explains why individuals with a painful temporomandibular joint usually prefer to bite on the side of the diseased joint.

Biomechanical Phenomena↗

PubMed2006

Anatomy of the equine temporomandibular joint: study by gross dissection, vascular injection and section.

REASONS FOR PERFORMING STUDY: The minute anatomy of the temporomandibular joint (TMJ) in horses is poorly documented in the literature. OBJECTIVES: To examine in detail the anatomy of the normal equine TMJ and the relationship of the joint to adjacent structures. METHODS: The anatomy of the TMJ was examined in 12 equidae using dissections, synovial and vascular injections and frozen and plastinated sections. Relevant structures were photographed. RESULTS: Rostral and caudal compartments were identified in the dorsal and ventral synovial pouches of the TMJ. Lateral and caudal ligaments were identified and attachments of the masticatory muscles over the TMJ were documented. Direct relationships between the TMJ and components of the ear were found, and the vascular supply described. CONCLUSIONS: This joint is related to some components of the ear as in man, and has its own peripheral vascular supply. POTENTIAL RELEVANCE: A knowledge of the detailed anatomy of the equine TMJ is a prerequisite to interpreting the imaging techniques, and will enable improved diagnosis of TMJ pathologies.

Animals↗

PubMed1990

Investigations on prevalence and treatment of fingernail biting.

Numerous investigations indicate that there is a parallel between emotional stress and hyperactivity of the masticatory muscles connected with mandibular parafunctions. Elimination of mandibular parafunctions is difficult and almost impossible, therefore, this paper proposed a treatment whereby nonharmful motor habits are substituted for the parafunction. Questionnaire investigations were carried out in 2905 subjects, with an attempt at treatment in the youngest group of 222 pupils. It was found that good results were obtained through adult supervision and cooperation.

Adolescent↗

PubMed2005

[CT and MRI features of diseases involving masticator spaces].

OBJECTIVE: This is a study on the CT and MRI features of diseases involving the masticator spaces; the purpose is to improve the diagnostic accuracy. METHODS: Fifty-seven cases involving the masticator spaces were collected, among which, 11 cases were originated from the masticator space, another 46 cases were secondary invasion from the adjacent structures, including 18 cases from the buccal mucosa, 10 from the nasopharynx, 5 from the gingiva, 3 from the parotid gland, 6 from the maxillary sinus, 1 from the intracranial location, 2 from the palate and 1 from the orbit. The CT and MRI features of the masticator space involvement were analysed. RESULTS: Masticator space involvement is visualized on CT and MRI as effacement of the fat plane, swelling of the masticatory muscles, and erosion of the mandibular ramus. Disease from surrounding structures can invade the masticator space via the pterygopalatine fossa, the buccal space immediately anterior to the ramus, the foramen ovale, or by way of direct invasion. CONCLUSION: Masticator space involvement is not uncommon in the maxillofacial diseases, which must be noticed in the imaging diagnosis.

Adolescent↗

PubMed1990

Craniomandibular stiffness toward maximum mouth opening in healthy subjects: a clinical and experimental investigation.

A new technique for measuring craniomandibular stiffness during mouth opening to the border position was tested. A small force transducer and a jaw tracking device were used to calculate the stiffness in a healthy group of male and female students. Simultaneous EMG recordings were taken from the masticatory muscles to observe the EMG activity during the experimental tests. The craniomandibular stiffness curves of the male group exhibited a stiffer behavior than those of the female group (P less than 0.05). The clinically obtained "endfeel" distance exhibited a significant correlation with different stiffness sections in the stiffness curves (P less than 0.05). Enhanced muscular involvement during mouth opening to the border position was shown as an increase in the clinical endfeel distance.

Electromyography↗