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PubMedDate not supplied

Salivary cortisol level, salivary flow rate, and masticatory muscle activity in response to acute mental stress: a comparison between aged and young women.

BACKGROUND: Age-related effects on physiological stress reactions regarding changes in salivary cortisol concentration, saliva flow rate, and masticatory muscle activity, as well as the corresponding perceived mental stress and performance in response to acute stressors, have not yet been fully described. OBJECTIVE: Thus, the aim of this study was to assess the age-related variations in these variables in response to minor acute and naturalistic stressors in terms of computer tasks. METHODS: 13 aged (60-70 years old) and 13 young (20-30 years old) women with frequent practice and long experience with computer use were recruited by personal contact and flyers. The subjects were healthy and had full dental arches and no orofacial pain. The computer tasks were randomized and comprised a mentally demanding, modified Stroop colour-word test (CWT) and a less demanding reference test, both with a duration of 20 min and with equal physical demand. Visual analogue scales for global assessment of mental stress and perceived task difficulty and performance, measurements of saliva flow rate and cortisol concentration (unstimulated whole saliva), as well as surface electromyography of the temporalis and masseter muscles were used for assessment, and Spearman correlation analysis and Anova with repeated measures were used for statistical evaluation. RESULTS: The perceived task-related stress and task difficulty were significantly higher and the personal satisfaction with the task performance significantly poorer in the aged women. The cortisol concentration, indicating the stress level, showed a small, but significant increase in response to the tasks. Also the saliva flow rate increased. This response was most pronounced in the aged and during the CWT. The average electromyogram varied significantly between age groups and tasks, with higher levels and shorter relative periods with gaps in the aged women and in the CWT. In addition, the peak activity of the jaw elevator muscles at mouse clicking was significantly elevated as a form of co-activation or attention-related activity. CONCLUSIONS: The study showed marked differences in the response to mental demands in aged as compared with young women. The mental stress, reflected by increases of salivary cortisol concentration, saliva flow rate, visual analogue scale ratings, and activity level of the jaw elevator muscles, was more pronounced in the aged women in response to the computer tasks.

Adult↗
PubMed1997

Swelling of the temporal region: a case of benign masticatory muscle hypertrophy.

A 35-year-old Caucasian woman had bilateral indolent swelling of the temporal regions. Imaging studies with nuclear magnetic resonance, ultrasonography and histopathological investigation revealed enlargement of the temporal and masseter muscles, with no pathology in the skin or subcutaneous tissue. A small prolactinoma of the pituitary gland was incidentally found. The condition, designated benign masticatory muscle hypertrophy, should be distinguished from similar diseases affecting the skin and the subcutaneous tissue of the scalp. The cause remains unknown.

Adult↗
PubMed1990

Histomorphometrical analysis of the influence of soft diet on masticatory muscle development in the muscular dystrophic mouse.

The known difference in the severity of dystrophy between the masseter and the digastric muscle of the mouse (dy/dy C57BL/J6) may be attributed to the differences in muscle work load. This possibility was tested by subjecting 3-week-old mice (normal and dystrophic) to a soft diet for 4 weeks. Microscopic examination of haematoxylin-eosin stained sections of these muscles showed that the fibre size dispersion (a measure of disease severity) decreased slightly but significantly in the masseters of mice on a soft diet. It was thus possible to improve the condition of dystrophic masticatory muscles by changing their function. Body weight curves measured during the experimental period suggest that the dystrophic mice may have been under weight because of malnutrition due to lack of sufficient masticatory power.

Animals↗
PubMed2003

Myosin heavy chain composition in human masticatory muscles by immunohistochemistry and gel electrophoresis.

In this study we compared the immunohistochemically quantified fiber type area with the myosin heavy chain (MyHC) contents of a bundle of fibers from a human masticatory muscle. The total cross-sectional areas were determined immunohistochemically for the three major fiber types (I, IIA, and IIX) in bundles of fibers (n=42) taken from the anterior and posterior belly of the human digastric muscle (n=7). The relative MyHC contents of the same fiber bundles were determined electrophoretically (MyHC-I, -IIA, and -IIX; anterior, 32%, 35%, and 33%; posterior, 39%, 42%, and 19%) and compared with the immunohistochemical data (MyHC-I, -IIA, and -IIX; anterior, 32%, 31%, and 37%; posterior, 39%, 45%, and 15%). No significant differences were seen in the mean fiber type distribution between the two techniques; the correlation coefficient ranged from 0.71 to 0.96. The correlation coefficient was higher for MyHC type I and MyHC type IIX than for MyHC type IIA. The MyHC contents of single fibers taken from the posterior belly indicated that many fibers in this belly co-express MyHC-IIA and MyHC-IIX. Despite the presence of these hybrid fibers, the correspondence between both methods was relatively large.

Aged↗
PubMed1999

[Evaluation of the bioelectrical activity of the masticatory muscles in patients depending on the period since implantation].

The results of electromyographic control used for evaluating the efficacy of orthodontic treatment are analyzed. Analysis of electromyographic parameters after orthodontic treatment of dentition defects with implants showed essential changes in the function of the masticatory muscles at different terms after implantation. Asymmetrical activity typical of unilateral chewing was observed, as well as high bioelectrical activity of the temporal muscles.

Dental Prosthesis, Implant-Supported↗
PubMed1994

[Effects of the orientation of occlusal plane on EMG of masticatory muscles in complete denture wearers].

The occlusal plane was designed as parallel to Camper's line (the standard dentures) and 5 degree inclined upward, downward laterally and anterior-posterior for comparing the activities of masticatory muscles. Following results were obtained: (1) the amplitude of the masseter (Mm) and the anterior temporalis (Ta) muscles with standard dentures biting in intercuspal position were the highest among those with other dentures, (2) during unilateral chewing with standard dentures, the average amplitude of the anterior digastric muscles (Da) on the balanced side was higher than that on the working side, but the amplitude values of the Mm and the Ta on the working side were significantly lower than those on the opposite side, (3) to incline the plane forward or backward may cause the activity of the Da increased in the balanced side and (4) to incline the plane right or left the amplitude of Ta and Mm between the working and the balanced side was not significant different.

Aged↗
PubMed2002

Trigeminal and polyradiculoneuritis in a dog presenting with masticatory muscle atrophy and Horner's syndrome.

A 9-year-old, spayed female, Airedale Terrier was euthanatized and necropsied after a progressive clinical course that included Horner's syndrome of the left eye and unilateral atrophy of the masticatory muscles. Although gross lesions were limited, a polyradiculoneuritis and ganglionitis that was most severe in the trigeminal nerves and ganglia were confirmed histologically. The inflammatory infiltrate consisted predominantly of macrophages and B and T lymphocytes that were phenotypically confirmed by immunostaining. Horner's syndrome was the result of damage to postganglionic sympathetic fibers that were incorporated in segments of the inflamed trigeminal nerve and its ophthalmic branch. Histologically, the character and distribution of the inflammation was similar to previously described syndromes of suspected immune-mediated etiology in humans and animals.

Animals↗
PubMed1995

[The electromyographic activity of the masticatory muscles during temporomandibular joint clicking].

16 patients with painless temporomandibular joint clicking were investigated electromyographically. EMGs were recorded during open-close movement from the superior and inferior heads of the lateral pterygoid muscle, the anterior belly of the digastric muscle and the temporal muscle. TMJ clicking was recorded with a microphone located over the TMJ simultaneously with EMG and incisal movement and velocity. 13 of 16 patients showed various changes in EMG patterns. 3 patients showed no changes in EMG patterns. Evidence that a hyperactive muscle induces TMJ clicking, was not observed. These results indicate that there may be many types of adaptation for TMJ clicking from the viewpoint of the various EMG findings of masticatory muscles. It is suggested that most of the electromyographic changes are not the cause of painless TMJ clicking but their result.

Adolescent↗
PubMed2006

A psychological study on patients with masticatory muscle disorder and sleep bruxism.

Sleep bruxism (SB) has been believed to be related to stress and psychosocial factors, however their implicit relationship has remained unclear. This study was conducted on patients visiting our clinic with SB and masticatory muscle disorders (MMD) for the purpose of clarifying personality and behavioral traits. This study was conducted on patients of MMD visiting our clinic. The Rosenzweig Picture-Frustration study was performed on each patient. Twenty-seven (27) patients were divided into two groups: 17 patients with SB and 10 patients without. The SB group showed a significantly lower level of E (extrapunitive) reaction than the nonSB group. SB patients showed a significantly higher level of M (impunitive) reaction than those without SB. Concerning the directions of aggression, the percentage of E-A (extraaggression) was significantly lower in SB patients than in those without. On the other hand, the percentage of I-A (intraaggression) was significantly higher in patients with SB than those without. Our study found a new aspect of the patients with MMD and SB: they are not only intraaggressive, but are also unable to be extrapunitive and extraaggressive. Consequently, they are unable to demonstrate adequate self-assertiveness in stressful situations.

Adolescent↗
PubMed1989

[Relationship between orofaciocranial morphologic factors and electromyographic activities of the masticatory muscles].

The purpose of this study is to evaluate the relationship between orofaciocranial morphologic and functional factors. The lateral cephalograms of 10 normal subjects were taken and traced. The authors divided cephalometric parameters into linear and angular measurements. Electromyographic (EMG) activities were recorded from bilateral anterior temporal and masseter muscles during tapping movement. Then the total muscle activity of both muscles, and the masseter muscle activity ratio in the total muscle activity were measured. The correlation coefficients between cephalometric measurements and EMG parameters were analyzed. The results of this study are as follows: 1) The total muscle activity revealed positive correlation with all the linear measurements. Especially, the total muscle activity significantly correlated with the size of mandible, such as Co-Go and Go-Me. 2) The total muscle activity showed a tendency to increase when the angles among SN plane, FH plane, maxillary base plane and mandibular border plane became small, and when S-N-A and S-N-B became large. 3) There was no correlation between masseter muscle activity ratio and cranial morphologic measurments. But masseter muscle activity ratio correlated with tooth position and anteroposterior inclination of the anterior teeth. These results suggest that the consideration of the relationship between orofaciocranial morphologic factors and EMG parameters is necessary for examining the masticatory muscle activity.

Cephalometry↗
PubMed1994

[Changes in the bioelectrical activity of the masticatory muscles and temporomandibular joint pathology in the myofascial pain dysfunction syndrome].

The authors consider the dependence of changes in the temporomandibular joint on the disease duration, analyze the relations between the clinical pattern of myofascial pain dysfunction syndrome (MPDS) and electromyographic changes in the masticatory muscles. Changes in the temporomandibular joint seemed to be of little importance for MPDS severity.

Adolescent↗
PubMed1977

[Electromyographic studies on the masticatory muscles after the preparation of terminal molars as denture abutments].

When the occlusal surfaces of terminal molars are ground off during bridge preparation, the occlusal support for the condyle of the affected side disappears and thus the intermaxillary distance declines. The effect of this process on the masticatory muscles was examined electromyographically in nine patients. It was found that the muscle activity especially in the m. temporalis is immediately reduced by 30 to 40%.

Adult↗
PubMed1979

[Headache due to functional disorders of the masticatory organ. Headache due to tension of the masticatory muscles].

Headache in the temporal, frontal and suboccipital regions are described as to case history, findings and differential diagnosis. With due respect to possible further symptoms of dysfunction, the author indicates as principles to treatment: 1. restoration of the continuity of the rows of teeth, and of the occlusal relations; 2. restoration of correct jaw relations; 3. rehabilitation of masticatory muscles.

Dental Occlusion, Centric↗
PubMed1997

Masticatory muscle function after unilateral condylar fractures: a prospective and quantitative electromyographic study.

Electromyographic (EMG) recording of masticatory muscle activity was performed in 9 adult men with unilateral condylar fracture immediately after conservative treatment of the condylar fracture (T0) and 4 (T1) and 8 (T2) months after the trauma. From T0 to T2, maximal voluntary contraction of the anterior and posterior temporal muscles and of the masseter muscle opposite the fracture side (contralateral) increased significantly. Activity in the anterior temporal muscles also rose significantly during natural chewing, whereas the masseter muscles remained at the same level, but activity consistently tended to be strongest contralaterally to the condylar fracture. In addition, there was a tendency from T1 to T2 for natural chewing to take place predominantly on the contralateral side. The most obvious overall changes during the follow-up were shorter and stronger contractions in all muscles during chewing, on the side of the impaired joint. The increase of activity in the anterior temporal muscles during maximal bite and natural chewing, and the occurrence of stronger and shorter contractions during ipsilateral chewing, were interpreted as signs of improved function due to healing and relief of pain from the impaired joint. On the other hand, there was a specific rise of maximal activity only in the contralateral masseter, and during natural chewing, activity was constantly stronger in the same muscle in combination with the tendency of increasing predominance of contralateral strokes. These traits specifically related to the masseter muscles were considered an indication of a permanent functional distortion due to reflex suppression on the fracture side as an after-effect of the injury.

Adult↗
PubMed2002

Correlation between facial patterns and function of the masticatory muscles in girls and women.

The relationship between maxillo-facial patterns and function of the masticatory muscles was evaluated using electromyography, in 16 women with functional normal occlusion and 16 girls with chronological normal occlusion half of them had the dolico facial pattern and the others had the brachyo facial pattern by Ricketts analysis. For the electromyography, loads of 1, 2, 3, 4, and 5 kg were applied to the mandible, and muscular activity waves were obtained from the masseter muscle and the anterior belly of the temporal muscle during isometric contraction by surface electrode induction. The median frequency value (MFV) in a frequency curve obtained by high-speed Fourier transform of the electromyographic waves was set to the evaluation index. The MFV at each applied load was higher in the adult brachyo facial pattern group than in the adult dolico facial pattern group in both the masseter and temporal muscles, whereas the differences in the MFV were slight in the child group at a 5% significance level. The child group showed approximately half the incidence of significant correlation coefficients in comparison with the adult group and a large standard deviation without marked differences in the facial patterns due to their individual differences in growth with a 5% significant level. The adult brachyo facial pattern group showed a high regression coefficient of the MFV in the masseter muscle according to the increase in the amount of the applied load. Although differences in the cooperative contraction patterns similar to those in the adult group were observed in both the child dolico and brachyo facial pattern groups, no marked significant differences were observed in the child group, who had large individual differences due to their immature growth.

Adolescent↗
PubMedDate not supplied

[Physiological duration of the silent period in masticatory muscles].

"Silent period" is the reflex pause or the period of suppressive activity that is subsequent to some sort of stimuli during or after the muscle contraction. In current dentistry, "silent period" registered by electromyography presents in functional diagnosis one of the parameters in revealing the functional disturbances of neuromuscular system. The aim of the study was to investigate the physiological duration of "silent period" in masticatory muscles. The group of examinees comprised 4 males and 4 females of average age 29 years. All the examinees were with healthy stomatognathic system and natural dentition. "Silent period" was registered by the apparatus "Medlec" Mystro-MS 20 using intramuscular electrodes. The results of the investigation indicated the different duration of physiological "silent period", depended on the type of investigated muscle.

Adult↗
PubMedDate not supplied

Automatic detection and measurement of EMG silent periods in masticatory muscles during chewing in man.

Silent periods are transient stops of muscle activity that are induced by mechanical or electrical stimulus. The current report describes a new algorithm which enables automatic detection and measurement of silent periods that occur in the EMG of human masticatory muscles during chewing efforts together with jaw positions in space at the occurrence of the silent periods. The EMG signal for detection of the silent period is modeled based on the observation of the EMG records induced from the jaw-closing muscles during chewing efforts in seven volunteer subjects. The algorithm for automatic detection and measurement of the EMG silent period has been applied successfully to real EMG data and the performance of the software was confirmed to be sufficiently reliable. The results of the analysis are stored in a biosignal database for possible clinical use.

Adult↗