-
Toxins Oct 2023This study aimed to evaluate the efficacy of botulinum toxin type A (BoNT/A) in patients with temporomandibular disorders (TMDs) associated with masticatory muscle pain... (Randomized Controlled Trial)
Randomized Controlled Trial
This study aimed to evaluate the efficacy of botulinum toxin type A (BoNT/A) in patients with temporomandibular disorders (TMDs) associated with masticatory muscle pain (MMP) and headaches. This randomized, double-blind, placebo-controlled pilot study is the first clinical trial to evaluate both disorders simultaneously. Twenty-one patients with myogenous TMD were randomly assigned to two groups. The experimental and control groups received injections of either BoNT/A or saline into the sites showing tenderness after palpation of a total of 16 muscle areas, including each masseter, a temporalis, splenius capitis, sternocleidomastoid, and trapezius muscle. During each visit, the clinical effects, based on the intensity of orofacial pain (OVAS), headache (HVAS), number of tender points (TPs), maximum mouth opening (MMO), and headache frequency (HF), were evaluated at four time points, namely, pre-injection and 4, 8, and 12 weeks after the injection, in both groups. Friedman and Mann-Whitney tests were used for the analyses. In the experimental group, the reductions in OVAS, TP, HVAS, and HF showed significant differences over time, excluding MMO, whereas there was no significant difference in any of the variables in the control group. In addition, the decline in TPs was significantly different between the experimental and control groups at all time points, especially after 4 and 12 weeks, compared to that during pre-injection. In conclusion, treatment with BoNT/A was relatively effective for masticatory muscle pain caused by TMDs and headache compared to the saline placebo.
Topics: Humans; Pilot Projects; Treatment Outcome; Masticatory Muscles; Botulinum Toxins, Type A; Myalgia; Headache; Temporomandibular Joint Disorders; Double-Blind Method
PubMed: 37888628
DOI: 10.3390/toxins15100597 -
PloS One 2023Both Achilles and masticatory muscle tendons are large load-bearing structures, and excessive mechanical loading leads to hypertrophic changes in these tendons. In the...
Both Achilles and masticatory muscle tendons are large load-bearing structures, and excessive mechanical loading leads to hypertrophic changes in these tendons. In the maxillofacial region, hyperplasia of the masticatory muscle tendons and aponeurosis affect muscle extensibility resulting in limited mouth opening. Although gene expression profiles of Achilles and patellar tendons under mechanical strain are well investigated in rodents, the gene expression profile of the masticatory muscle tendons remains unexplored. Herein, we examined the gene expression pattern of masticatory muscle tendons and compared it with that of Achilles tendons under tensile strain conditions in the Japanese macaque Macaca fuscata. Primary tenocytes isolated from the masticatory muscle tendons (temporal tendon and masseter aponeurosis) and Achilles tendons were mechanically loaded using the tensile force and gene expression was analyzed using the next-generation sequencing. In tendons exposed to tensile strain, we identified 1076 differentially expressed genes with a false discovery rate (FDR) < 10-10. To identify genes that are differentially expressed in temporal tendon and masseter aponeurosis, an FDR of < 10-10 was used, whereas the FDR for Achilles tendons was set at > 0.05. Results showed that 147 genes are differentially expressed between temporal tendons and masseter aponeurosis, out of which, 125 human orthologs were identified using the Ensemble database. Eight of these orthologs were related to tendons and among them the expression of the glycoprotein nmb and sphingosine kinase 1 was increased in temporal tendons and masseter aponeurosis following exposure to tensile strain. Moreover, the expression of tubulin beta 3 class III, which promotes cell cycle progression, and septin 9, which promotes cytoskeletal rearrangements, were decreased in stretched Achilles tendon cells and their expression was increased in stretched masseter aponeurosis and temporal tendon cells. In conclusion, cyclic strain differentially affects gene expression in Achilles tendons and tendons of the masticatory muscles.
Topics: Animals; Humans; Achilles Tendon; Gene Expression Profiling; Macaca fuscata; Masseter Muscle; Masticatory Muscles; Tendons
PubMed: 36656905
DOI: 10.1371/journal.pone.0280649 -
Clinical and Experimental Dental... Jun 2023The purpose of this study was to elucidate how masticatory muscles are involved in the generation of occlusal force.
OBJECTIVES
The purpose of this study was to elucidate how masticatory muscles are involved in the generation of occlusal force.
MATERIALS AND METHODS
The experiment was conducted by fabricating an experimental apparatus for a unilateral occlusion model with the masticatory muscles imparted. The experimental apparatus was fabricated by enlarging the lateral photograph of a dried adult skull specimen 3.5 times larger than that of a standard adult and drawing the outlines of the maxilla and mandible, canines and molars of the upper and lower jaws, and temporomandibular joint on a wooden board. The masticatory muscles used in the experiment were the masseter muscle, the temporalis muscle (anterior and posterior muscle bundles), and the lateral pterygoid muscle. For the measurement of the contractile force of the masticatory muscle, we used the spring scale. For the food, we used cut plastic cylinders.
RESULTS
The results of the experiment revealed the following: First, the occlusal force was generated under the condition that the contraction forces of all the masticatory muscles were balanced. Second, when the occlusal force was applied to food, the occlusal planes of the upper and lower jaws were parallel. Third, the occlusal force occurred perpendicular to the occlusal plane. Fourth, the occlusal force was generated with a force greater than the contraction force of the individual masticatory muscles. And finally, even if occlusal force was applied to the food, the occlusal force did not load the temporomandibular joint.
CONCLUSION
Occlusal force is not generated by the action of a single masticatory muscle but under the balanced contractile force of all masticatory muscles. The occlusal force then emerges with a force greater than the contraction force of all the masticatory muscles, and its direction occurs perpendicular to the occlusal plane.
Topics: Masseter Muscle; Bite Force; Masticatory Muscles; Pterygoid Muscles; Maxilla
PubMed: 36924025
DOI: 10.1002/cre2.725 -
Anatomical Record (Hoboken, N.J. : 2007) Feb 2022Carnivorans represent extreme ecomorphological diversity, encompassing remarkable variation in form, habitat, and diet. The relationship between the masticatory...
Carnivorans represent extreme ecomorphological diversity, encompassing remarkable variation in form, habitat, and diet. The relationship between the masticatory musculature and dietary ecology has been explored in a number of carnivoran lineages, including felids and the superfamily Musteloidea. In this study, we present novel architectural data on two additional carnivoran families-Ursidae and Canidae-and supplement these previous studies with additional felid, musteloid, herpestid, hyaenid, and viverrid taxa (a total of 53 species across 10 families). Gross dissection data were collected following a standardized protocol-sharp dissection followed by chemical digestion. Summed jaw adductor forces were also transformed into bite force estimates (BF) using osteologically calculated leverages. All data were linearized, log-transformed, and size-adjusted using two proxies for each taxon-body mass (BM) and cranial geometric mean-to assess relative scaling trends. These architectural data were then analyzed in the context of dietary ecology to examine the impact of dietary size (DS) and dietary mechanical properties (DMP). Muscle mass, physiological cross-sectional area, and BF scaled with isometry or positive allometry in all cases, whereas fascicle lengths (FLs) scaled with isometry or negative allometry. With respect to diet, BM-adjusted FLs were strongly correlated with DS in musteloids, but not in any other lineage. The relationship between size-adjusted BF and DMP was also significant within musteloids, and across the sample as a whole, but not within other individual lineages. This interfamilial trend may reflect the increased morphological and dietary diversity of musteloids relative to other carnivoran groups.
Topics: Animals; Canidae; Carnivora; Diet; Felidae; Humans; Masticatory Muscles; Ursidae
PubMed: 34449131
DOI: 10.1002/ar.24748 -
BioMed Research International 2021This pre-post study is aimed at determining the effects of masticatory muscle activity (masseter and temporalis) measured via sEMG between conventional, self-ligating,...
OBJECTIVE
This pre-post study is aimed at determining the effects of masticatory muscle activity (masseter and temporalis) measured via sEMG between conventional, self-ligating, and ceramic bracket after six months of orthodontic treatment.
METHODS
A total of eighteen (18) malocclusion patients were identified. Malocclusion patients were subdivided into 3 groups based on the bracket selection (conventional, self-ligating, and ceramic bracket) with 6 patients for each group. sEMG of muscles were done using a two-channel electromyography device, where pregelled and self-adhesive electrodes (bilateral) were applied. Chewing and clenching of masseter and temporalis muscle activity were recorded for 20 s pre and 6 months of orthodontic treatment using sEMG (frequency 60 Hz). The data were analysed by using repeated measures ANOVA in IBM SPSS Statistics Version 24.0.
RESULTS
Chewing and clenching for masseter muscle showed no significant difference ( > 0.05) in sEMG activity of three types of the brackets. However, for temporalis muscle, there was a significant difference found in sEMG activity during chewing ( < 0.05) and clenching ( < 0.05) between these three brackets.
CONCLUSION
The activity of temporalis muscle showed significant changes in chewing and clenching, where the conventional group demonstrated better muscle activity pre and at six months of fixed appliances.
Topics: Electrodes; Electromyography; Female; Humans; Male; Masseter Muscle; Mastication; Orthodontic Brackets; Temporal Muscle
PubMed: 33969121
DOI: 10.1155/2021/6642254 -
Pain Research & Management 2020Temporomandibular joint dysfunction (TMD) is a chronic disease of various etiologies. Correct TMD diagnosis enables to apply effective treatment and significantly... (Review)
Review
Temporomandibular joint dysfunction (TMD) is a chronic disease of various etiologies. Correct TMD diagnosis enables to apply effective treatment and significantly improves the quality of patients' lives. One of the diagnostic methods subjected to evaluation in recent years is thermography, which enables safe, noninvasive, and quick imaging of the temperature distribution of temporomandibular joint-associated tissues. This paper, based on Medline, Dentistry & Oral Sciences Source, Academic Search Ultimate, Medline Complete databases, presents basic information related to thermovision imaging and outlines the direction of research conducted in recent years which fight with difficulties in the interpretation of thermograms that require specialized, dedicated analysis and processing of the obtained images. The problem concerns also no standardized protocol for measuring masticatory muscle temperature.
Topics: Female; Humans; Masseter Muscle; Masticatory Muscles; Temporomandibular Joint; Temporomandibular Joint Disorders; Thermography
PubMed: 33282037
DOI: 10.1155/2020/5481365 -
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 -
Journal of Oral Rehabilitation Dec 2020Clinical findings suggest that orthodontic treatment with clear aligners (clear aligner therapy/CAT) may cause masticatory muscle soreness in some patients.
BACKGROUND
Clinical findings suggest that orthodontic treatment with clear aligners (clear aligner therapy/CAT) may cause masticatory muscle soreness in some patients.
OBJECTIVE
This multi-site prospective study investigated tooth pain and masticatory muscle soreness and tenderness in patients undergoing CAT and explored whether psychological traits affected these outcomes.
METHODS
Twenty-seven adults (22F, 5M; mean age ± SD=35.3 ± 17.6 years) about to start CAT were recruited at three clinics. During CAT, they reported on 100-mm visual analogue scales their tooth pain, masticatory muscle soreness and stress three times per day over 4 weeks (week 1 = baseline; week 2 = dummy aligner; week 3 = first active aligner; week 4 = second active aligner). Pressure pain thresholds (PPTs) were measured at the masseter and temporalis at baseline and after week 4. Mixed models were used to evaluate the outcome measures over time.
RESULTS
Clear aligner therapy caused mild tooth pain, which was greater with the passive than the first and second active aligners (both P < .001). Mild and clinically not relevant masticatory muscle soreness was produced by all aligners (all P < .05), with the first active aligner producing less soreness than the dummy aligner (P < .001). PPTs did not change significantly after 4 weeks. Both tooth pain and masticatory muscle soreness were affected by stress and trait anxiety, whilst muscle soreness was affected also by oral behaviours.
CONCLUSIONS
In the short term, CAT produces tooth pain and masticatory muscle soreness of limited significance. Frequent oral behaviours are related to increased masticatory muscle soreness during CAT. The medium- and long-term effects of CAT should be further explored.
Topics: Adult; Humans; Masseter Muscle; Masticatory Muscles; Myalgia; Orthodontic Appliances, Removable; Pain Threshold; Prospective Studies
PubMed: 32898936
DOI: 10.1111/joor.13088 -
International Journal of Environmental... Feb 2020Masticatory muscle activity during teeth clenching is associated with changes in many physiological parameters throughout the body. Clenching can improve muscle...
Masticatory muscle activity during teeth clenching is associated with changes in many physiological parameters throughout the body. Clenching can improve muscle activity, force production, rate of force development, and joint fixation. Hence, teeth clenching and masticatory muscle activity can be important in competitive sports activities. Sport climbing is becoming increasingly popular and will be included for the first time in the Summer Olympic Games, Tokyo, 2020. However, masticatory muscle activity in sport climbers has not yet been studied. The aim of the presented study is to compare the bioelectrical activity of the masticatory muscles in sport climbers and non-climbers in order to determine the relationship between these muscles and climbing activity. 44 subjects without masticatory system disorders (16 women and 28 men, average age 26.3) were divided into two groups of 22 sport climbers (8 women, 14 men, climbing experience >4 years), while 22 people (8 women, 14 men, with no regular sports activity) were assigned to the control group. Electromyographic examination of temporalis anterior (TA) and masseter muscle (MM) was evaluated in three conditions: during resting mandibular position, during maximum intercuspation clenching, and during maximum voluntary clenching with cotton rolls between teeth. For statistical analysis, the W Shapiro-Wilk test and the Mann-Whitney U test were used. Sport climbers showed significantly higher bioelectrical activities of MM during maximum intercuspation clenching (238.45 μV vs. 83.87 μV, = 0.002), and during maximum voluntary clenching with cotton rolls between teeth (300.01 μV vs. 101.38 μV, = 0.001) compared to controls. The differences between groups in relation to the resting bioelectrical activity of the MM muscles, and TA muscles in all conditions were not statistically significant ( > 0.05). Higher bioelectrical activity of masseter muscles during clenching in climbers can be associated with this sports activity. However, the mechanism remains unknown and requires future research.
Topics: Adult; Electromyography; Female; Humans; Male; Masticatory Muscles; Muscle Contraction; Sports; Temporal Muscle; Tokyo; Young Adult
PubMed: 32098017
DOI: 10.3390/ijerph17041378 -
Archives of Oral Biology Feb 2019The aim was to investigate relationships amongst interocclusal distances, masticatory muscle electromyographic (EMG) activity during isometric contraction of masticatory...
OBJECTIVE
The aim was to investigate relationships amongst interocclusal distances, masticatory muscle electromyographic (EMG) activity during isometric contraction of masticatory muscles, and craniofacial morphology.
DESIGN
Twenty-eight women and 12 men (25.3 ± 3.8 years old) participated. After measuring maximal voluntary occlusal bite force (MVOBF) between the right-first premolars, the participants were asked to bite at submaximal levels of 0 (= holding the bite force transducer), 15, 22.5, and 30% MVOBF with the use of visual feedback. The thickness of a bite force transducer was set at 10, 12, 13, 14, 16, 17, 18, 19, 20, 22, and 24 mm (= interocclusal distance: IOD). Nine soft tissue craniofacial factors were assessed through digital photograph: face height, middle face height, lower face height, face width, inter-pupil distance and mandibular plane angle, lower face height / face height ratio, inter-pupil distance / facial width ratio and face width / face height ratio.
RESULTS
In the masseter muscle, EMG activity decreased with increased IODs. The participants with higher mandibular plane angle had more negative slope coefficients of IOD-EMG graphs at 0% MVOBF especially in male temporalis and female masseter and temporalis muscles, suggesting that a greater mandibular plane angle is associated with lower EMG activity at longer IOD.
CONCLUSIONS
Overall the findings support the notion that craniofacial morphology is associated with differences in neuromuscular activity of the masticatory muscles, and suggest that the neuromuscular effects of oral appliances may be dependent on patients' craniofacial morphology and the thickness of the device. (247/250 words).
Topics: Adult; Analysis of Variance; Anthropometry; Bite Force; Dental Occlusion; Electromyography; Face; Female; Humans; Isometric Contraction; Linear Models; Male; Masseter Muscle; Masticatory Muscles; Muscle Contraction; Regression Analysis; Sex Factors; Temporal Muscle; Trigeminal Nerve; Young Adult
PubMed: 30448395
DOI: 10.1016/j.archoralbio.2018.10.030