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BMC Oral Health May 2023Occlusal splints are always applied on individuals with bruxism to reduce tooth wear and relieve orofacial symptoms such as myofascial pain. The stomatognathic system is...
OBJECTIVE
Occlusal splints are always applied on individuals with bruxism to reduce tooth wear and relieve orofacial symptoms such as myofascial pain. The stomatognathic system is mainly composed of tooth, occlusion, masticatory muscles, and temporomandibular joint. The occlusion and masticatory muscles function are regarded as the important parameters for evaluating the stomatognathic system state objectively. However, the effects of occlusal splints on individuals with bruxism is rarely elucidated from accurate neuromuscular analysis and occlusion evaluation. The aim of the present study was to estimate the effects of three different splints (two clinically common full coverage occlusal splint and an modified anterior splint) on subjects with bruxism using K7-J5 neuromuscular analysis system and Dental Prescale II (DP2) to evaluate occlusion.
METHODS
Sixteen subjects claimed to be suffering from nocturnal bruxism,with complete dentition and stable occlusal relationship, were selected for study.The intermaxillary space and the baselines of EMG-activity of the anterior temporalis and masseter were recorded for all the subjects. The participants was treated with three different splints, and outcomes were estimated by comfort index, occlusion and surface electromyography of anterior temporalis and masseter.
RESULTS
At teeth clenched position, EMG data were significantly lower in the participants with use of modified anterior splint than with hard, soft occlusal splint or without splint (p < 0.05). The maximum bite force and bite area occur in subjects without use of splint, while the minimal occur in subjects with use of modified anterior splint. Intermaxillary space increased and masticatory muscles presented significant reduction of EMG data at rest position as a result of J5 (p < 0.05).
CONCLUSION
Modified anterior splint seems to be more comfortable and effective in reducing occlusion force and electromyographic activity of anterior temporalis and masseter for subjects with bruxism.
Topics: Humans; Splints; Bruxism; Dental Occlusion; Masticatory Muscles; Masseter Muscle; Electromyography
PubMed: 37231466
DOI: 10.1186/s12903-023-03044-5 -
Dental and Medical Problems 2021The masseter muscle can be evaluated in various ways to examine its condition in healthy individuals or to identify pathological changes in the muscle.
BACKGROUND
The masseter muscle can be evaluated in various ways to examine its condition in healthy individuals or to identify pathological changes in the muscle.
OBJECTIVES
This study aimed to examine the tone and viscoelastic parameters of the masseter muscle, which is the focal muscle of various pathologies, to reveal its relationship with age and gender, and to determine the reference values of this muscle in healthy individuals.
MATERIAL AND METHODS
Individuals aged 18-50 years were evaluated. They were divided into 3 groups in terms of age. A total of 389 individuals participated in the study (18-28 years: 131 males, 104 females; 29-39 years: 29 males, 56 females; and 40-50 years: 30 males, 39 females). The tone and viscoelastic properties of the masseter muscle were evaluated bilaterally in the supine position.
RESULTS
The mean age of all individuals was 28.64 ±9.68 years. The masseter muscle tone was found to be higher in men than in women. The elasticity of the muscle was higher in women (p < 0.05). It was determined that the masseter muscle tone and stiffness increased, whilst its elasticity decreased with aging (p < 0.05). A weak positive correlation was found between the right and left masseter muscle tone and age (r = 0.307 and r = 0.325, respectively; p = 0.001). There was a moderate positive correlation between the right and left masseter muscle stiffness and age (r = 0.507 and r = 0.511, respectively; p = 0.001). A strong positive correlation was observed between the right and left masseter muscle elasticity and age (r = 0.614 and r = 0.645, respectively; p = 0.001).
CONCLUSIONS
The data obtained in this study may assist clinicians in evaluating the treatment of the pathological conditions related to the masseter muscle as well as in the planning of treatment and preand post-operation evaluations. Cite as.
Topics: Adolescent; Adult; Aging; Elasticity; Female; Humans; Male; Masseter Muscle; Muscle Tonus; Supine Position; Young Adult
PubMed: 34076970
DOI: 10.17219/dmp/132241 -
The Kurume Medical Journal 2012To chew, it is necessary to maintain harmony between the masseter muscle and other organs. Various studies have been conducted on the masseter muscle, but none has...
To chew, it is necessary to maintain harmony between the masseter muscle and other organs. Various studies have been conducted on the masseter muscle, but none has examined the relationships among masseter muscle form, occlusal support of remaining teeth, and maxillofacial morphology. Thus, we conducted the present study using cadavers donated to anatomy practice. After the masseter muscle was extracted, its length, width, thickness, and volume were measured; histological observations were conducted; and the muscle fiber cross-sectional area and muscle density were calculated. In addition, denture use and non-use were examined. The results showed that when regional support loss occurs, muscle fiber thickness and density decrease. This in turn causes masseter muscle thickness and volume to decrease, resulting in muscle atrophy. Furthermore, excluding Eichner class A cases (all regions intact), the thickness of the masseter muscle is greatest when the premolar support region remains. The premolar support region was shown to have the most impact on masseter muscle morphology. These results suggest that atrophy of the masseter muscle can be arrested or improved with the use of dentures in the case of tooth loss.
Topics: Cadaver; Dental Occlusion; Humans; Masseter Muscle; Tooth
PubMed: 23257633
DOI: 10.2739/kurumemedj.59.5 -
Journal of Prosthodontic Research Jan 2024To evaluate the reproducibility and reliability of a novel electromyogram (EMG) device with a flexible sheet sensor for measuring muscle activity related to mastication...
PURPOSE
To evaluate the reproducibility and reliability of a novel electromyogram (EMG) device with a flexible sheet sensor for measuring muscle activity related to mastication and swallowing.
METHODS
We developed a new EMG device made of elastic sheet electrodes to measure the masseter and digastric muscle activities for evaluating mastication and swallowing. To examine the measurement reproducibility of the new EMG device, masseter muscle activity was analyzed using the intraclass correlation coefficient (ICC). Further, we measured the maximum amplitude, duration, integrated value, and signal-to-noise ratio (SNR) using the new EMG device and conventional EMG devices and evaluated the reliability using ICC and Bland-Altman analysis.
RESULTS
We confirmed high ICC (1,1) and ICC (2,1) scores (0.92 and 0.88, respectively) while measuring the reproducibility of the new EMG device. When compared to the active electrode EMG device, we found a high correlation for the maximum amplitude (0.90), duration (0.99), integrated values (0.90), and SNR (0.75), with no observation of significant fixed errors. Moreover, the regression coefficient was not significant for any of the evaluation items and no proportional error was observed. Compared with the passive electrode EMG device, the maximum amplitude and duration were highly correlated (0.73 and 0.89). In addition, the SNR exhibited a significant fixed error. In contrast, the regression coefficient was not significant for any of the evaluation items and no proportional error was observed.
CONCLUSIONS
Our results suggest that the new EMG device can be used to reliably and reproducibly evaluate muscle activity during mastication and swallowing.
Topics: Masseter Muscle; Electromyography; Reproducibility of Results; Mastication; Electrodes
PubMed: 37197948
DOI: 10.2186/jpr.JPR_D_22_00239 -
Annals of Palliative Medicine Mar 2021Despite the association of masticatory function with head posture and mandible movement, the impact of head posture on masseter muscle electrical activity remains...
BACKGROUND
Despite the association of masticatory function with head posture and mandible movement, the impact of head posture on masseter muscle electrical activity remains unclear. This study aimed to investigate the electrical activity of the anterior temporal, masseter, superior trapezius, and sternocleidomastoid muscles in temporomandibular disorder (TMD) patients in three different head positions and compare the findings with those for healthy subjects.
METHODS
The study included 16 TMD patients and 17 healthy subjects. Surface electromyography (sEMG) was used to assess the bilateral anterior temporalis, masseter, superior trapezius, and sternocleidomastoid muscle activities. The maximal voluntary contraction (MVC) and root mean square (RMS) sequence of each muscle were measured in three head positions. Mixed analysis of variance was used to evaluate the effects of head posture on muscle electrical activity in each group.
RESULTS
The group differences for the bilateral masseter muscles were significant in the relaxation position, neutral head position (NHP), and relaxation position with tooth contact (P<0.05). In both groups, the basal RMSs of the bilateral anterior temporalis muscle in the relaxation position with tooth contact was significantly higher than that in the NHP (P<0.05). In both groups, the basal RMSs of the bilateral masseter muscles in the relaxation position with tooth contact was higher than that in the relaxation position and NHP, with significant differences (P<0.05).
CONCLUSIONS
During the management of TMD patients, physical therapists should focus on patient education regarding maintenance of a relaxed position and establish appropriate rehabilitation programs to reduce muscle activity.
Topics: Healthy Volunteers; Humans; Masseter Muscle; Masticatory Muscles; Posture; Temporomandibular Joint Disorders
PubMed: 33691457
DOI: 10.21037/apm-20-1850 -
Medical Science Monitor : International... Jan 2021BACKGROUND Chewing dysfunction is one of the most common serious complications after a stroke. It may be influenced by the hardness of the masseter muscle and...
Quantification of the Masseter Muscle Hardness of Stroke Patients Using the MyotonPRO Apparatus: Intra- and Inter-Rater Reliability and Its Correlation with Masticatory Performance.
BACKGROUND Chewing dysfunction is one of the most common serious complications after a stroke. It may be influenced by the hardness of the masseter muscle and masticatory performance; however, the association between these 2 factors is not explicit. Thus, it is meaningful to explore the functional status of the masseter muscle among stroke patients. The main objectives of this study were to examine the intra- and inter-rater reliability of the MyotonPRO apparatus in measuring masseter muscle hardness in stroke patients and to investigate the correlation between the bilateral masseter muscle hardness and masticatory performance in these patients. MATERIAL AND METHODS A total of 20 stroke patients participated in our study. The hardness of the masseter muscle was measured by 2 physiotherapists using the MyotonPRO apparatus. Overall, each patient masticated 2 pieces of red-blue bicolor chewing gum for 20 chewing cycles each. The chewing pieces were analyzed using ViewGum software for masticatory performance. RESULTS The intra- and inter-rater reliability of the MyotonPRO apparatus for measuring bilateral masseter hardness of stroke patients was excellent. The correlation analysis showed that the hardness index of the masseter muscle on the affected side was moderately correlated with the masticatory performance of the same side. CONCLUSIONS The MyotonPRO device can be used for measuring the masseter muscle hardness of stroke patients, with excellent reliability. This study established the construct validity between the stiffness of the masseter muscle and masticatory performance.
Topics: Adult; Chewing Gum; China; Electromyography; Female; Hardness; Humans; Male; Masseter Muscle; Mastication; Middle Aged; Reproducibility of Results; Stroke
PubMed: 33515446
DOI: 10.12659/MSM.928109 -
Journal of Oral Rehabilitation Jan 2021In skeletal muscle, free nerve endings are mostly located within the connective tissue. However, the distribution of sensory afferent fibres in healthy human masseter...
BACKGROUND
In skeletal muscle, free nerve endings are mostly located within the connective tissue. However, the distribution of sensory afferent fibres in healthy human masseter muscle tissues has not been studied.
OBJECTIVES
Primarily to investigate human masseter muscle nerve fibre densities as well as expression of NR2B receptors, substance P (SP) and nerve growth factor (NGF), and secondarily to compare this between a) nerve fibres associated with myocytes and within connective tissue; b) sexes; and c) ages.
METHODS
Microbiopsies of the masseter muscle were obtained from 60 sex- and age-matched healthy participants. Biopsy sections were analysed using immunohistochemistry and were visualised with a Leica TCS SPE confocal microscope. The Mann-Whitney U test was used for statistical analyses.
RESULTS
The density of nerve fibres within connective tissue was significantly greater than in nerve fibres associated with myocytes (P < .001). Nerve fibres within connective tissue expressed SP alone or together with NR2B significantly more often than those associated with myocytes (P < .001). The frequency of nerve fibres, which expressed SP alone or in combination with NR2B or NGF, was significantly greater in women than in men (P < .050). Moreover, the co-expression of the three markers together was inversely correlated with age in women (P < .002).
CONCLUSIONS
There is a higher density and greater expression of sensory nerve fibres within the connective tissue than associated with myocytes in healthy human masseter muscle. This suggests that nerve fibres within connective tissue are more involved in nociception than nerve fibres associated with myocytes.
Topics: Female; Humans; Male; Masseter Muscle; Muscle, Skeletal; Nerve Fibers; Nerve Growth Factor; Substance P
PubMed: 33031568
DOI: 10.1111/joor.13109 -
Advances in Clinical and Experimental... Apr 2021As ultrasonography provides objective parameters and values, it is a reliable method of examining the structure and dimensions of the masseter muscle. Although the...
BACKGROUND
As ultrasonography provides objective parameters and values, it is a reliable method of examining the structure and dimensions of the masseter muscle. Although the method is well known, there is no standardization in clinical examination and data analysis yet.
OBJECTIVES
The study aimed to measure masseter muscle thickness in designated areas to establish the most repeatable and clinically applicable method of ultrasound examination, and to assess differences in measurements in designated areas for clinical purposes by devising the size-independent parameter. The size-independent parameter may potentially be more clinically applicable than distance records, which are affected by the size of the subject.
MATERIAL AND METHODS
An ultrasound examination of 124 masseter muscles was performed. Axial examination in 3 horizontal regions (lower, middle and upper) and coronal examination in 2 vertical regions (proximal and distal) was carried out. Masseter muscle thickness was measured in every designated area when relaxed (muscle at rest (RMT)) and with clenched teeth (contracted muscle (CMT)). A morphological independent functional index of thickness difference (FITD) was calculated.
RESULTS
The study revealed very high statistical differences between RMT and CMT (p < 0.0001) in all designated areas but with location variations. Masseter muscle thickness significantly differed depending on the examined area and transducer projection.
CONCLUSIONS
The ultrasound study showed that masseter muscle thickness significantly differs depending on the examined area. The authors emphasize the necessity to examine the masseter muscle in specified areas with both coronal and axial projections to achieve objective and repeatable examination. Notable clinical value is assigned to FITD, which is independent from the morphological dimensions of the muscle.
Topics: Masseter Muscle; Reference Standards; Ultrasonography
PubMed: 33913263
DOI: 10.17219/acem/130358 -
La Radiologia Medica May 2024Dysfunction of the masseter muscle may cause pathological kinking of the parotid duct leading to parotitis; MR sialography is a non-invasive radiological examination...
Dysfunction of the masseter muscle may cause pathological kinking of the parotid duct leading to parotitis; MR sialography is a non-invasive radiological examination that allows to evaluate dynamically the ductal system of the parotid glands. In the present study we aimed to assess the relationships between Stensen's duct and masseter muscle and their implications in the aetiopathogenesis of recurrent parotitis secondary to masseter muscle dysfunction. Forty-one patients with recurrent unilateral parotitis and nine with bilateral recurrent parotitis, all with a clinical suspicious of masseter muscle hypertrophy due to bruxism were enrolled. They underwent ultrasonography as a first line examination and then MR sialography and sialendoscopy. Different anatomical features were studied. Involved parotid glands had a wider duct compared to contralateral unaffected parotid glands of patients with recurrent parotitis (p = 0.00134); male subjects with parotitis had a longer duct compared to the salivary glands of healthy patients (p = 0.00943 for affected glands and p = 0.00629 for the contralateral). A concordance between the evidence of an acute duct angle during sialendoscopy and a wider duct in patients with parotitis was observed although not statistically significant. These initial findings suggest that the masticatory muscle dysfunction related to bruxism seems to condition alteration of parotid duct course and anatomy thus favouring the occurrence of recurrent parotitis. A specific diagnostic iter based on clinical evaluation, dynamic ultrasonography and MR sialography, is therefore, mandatory to confirm the relationship between masseter muscle anatomy and parotid duct anomalies; this is the premise for an adequate therapeutic approach to underlying masticatory muscle disorder.
Topics: Humans; Male; Parotitis; Female; Masseter Muscle; Adult; Middle Aged; Magnetic Resonance Imaging; Sialography; Recurrence; Salivary Ducts; Ultrasonography; Aged; Bruxism; Endoscopy
PubMed: 38512620
DOI: 10.1007/s11547-024-01802-1 -
PloS One 2014Critical illness myopathy (CIM) is a debilitating common consequence of modern intensive care, characterized by severe muscle wasting, weakness and a decreased...
Critical illness myopathy (CIM) is a debilitating common consequence of modern intensive care, characterized by severe muscle wasting, weakness and a decreased myosin/actin (M/A) ratio. Limb/trunk muscles are primarily affected by this myopathy while cranial nerve innervated muscles are spared or less affected, but the mechanisms underlying these muscle-specific differences remain unknown. In this time-resolved study, the cranial nerve innervated masseter muscle was studied in a unique experimental rat intensive care unit (ICU) model, where animals were exposed to sedation, neuromuscular blockade (NMB), mechanical ventilation, and immobilization for durations varying between 6 h and 14d. Gel electrophoresis, immunoblotting, RT-PCR and morphological staining techniques were used to analyze M/A ratios, myofiber size, synthesis and degradation of myofibrillar proteins, and levels of heat shock proteins (HSPs). Results obtained in the masseter muscle were compared with previous observations in experimental and clinical studies of limb muscles. Significant muscle-specific differences were observed, i.e., in the masseter, the decline in M/A ratio and muscle fiber size was small and delayed. Furthermore, transcriptional regulation of myosin and actin synthesis was maintained, and Akt phosphorylation was only briefly reduced. In studied degradation pathways, only mRNA, but not protein levels of MuRF1, atrogin-1 and the autophagy marker LC3b were activated by the ICU condition. The matrix metalloproteinase MMP-2 was inhibited and protective HSPs were up-regulated early. These results confirm that the cranial nerve innervated masticatory muscles is less affected by the ICU-stress response than limb muscles, in accordance with clinical observation in ICU patients with CIM, supporting the model' credibility as a valid CIM model.
Topics: Animals; Critical Care; Critical Illness; Disease Models, Animal; Female; Masseter Muscle; Muscle Weakness; Muscular Diseases; Protein Biosynthesis; Proteolysis; Rats; Rats, Sprague-Dawley; Wasting Syndrome
PubMed: 24705179
DOI: 10.1371/journal.pone.0092622