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Journal of Dentistry Apr 2024Standardized bite training is required to prevent oral hypofunction in elderly individuals. We aimed to compare masticatory muscle activity between 24 young adults and...
OBJECTIVES
Standardized bite training is required to prevent oral hypofunction in elderly individuals. We aimed to compare masticatory muscle activity between 24 young adults and 16 pre-elderly individuals during a biting task using a novel standardized bite device (BD).
METHODS
The BD was made of silicone rubber and included a high-force or low-force plate spring or no plate spring (dummy). The compressive stiffness of the material in each BD was measured using a texture analyzer. All participants performed a biting task 50-times at a rate of 1/s each using the three types of BDs on the right first molar. Electromyographic (EMG) activity was recorded bilaterally from the masseter and temporalis muscles. The variability of each biting training session was calculated as the coefficient of variance (CV) from the EMG activity during each biting task for each muscle. Masticatory muscle fatigue was assessed using a numerical rating scale (NRS).
RESULTS
Compressive stiffness was significantly different between each BD (P < 0.001). The CV and NRS scores were not significantly different between the groups. The EMG activities during each bite task in all muscles were not significantly different for any measurement item between the age groups. The EMG activities of high- and low-force BDs in the right temporalis (ipsilateral) muscle were significantly higher than those of the dummy BD (P < 0.001).
CONCLUSIONS
Compressive stiffness of the BD affected EMG activity only in the ipsilateral temporalis muscle, but not in the masseter or contralateral temporalis muscles, without any age effect.
Topics: Humans; Young Adult; Aged; Bite Force; Masticatory Muscles; Masseter Muscle; Temporal Muscle; Electromyography
PubMed: 38360395
DOI: 10.1016/j.jdent.2024.104887 -
Cell Proliferation Jun 2024Orofacial muscle defect due to congenital anomalies, tumour ablation or traumatic accident that exceeds endogenous regeneration capacity may lead to sustained deficits...
Orofacial muscle defect due to congenital anomalies, tumour ablation or traumatic accident that exceeds endogenous regeneration capacity may lead to sustained deficits in masticatory function and nutrition intake. Functional recovery has always been the goal of muscle tissue repair, but currently, there is no suitable model for quantitative analyses of either functional consequences or treatment efficacy of orofacial muscle defect. This study proposed a critical size volumetric muscle loss (VML) model in mouse masseter with impaired mastication on nutrition. Full-thickness VML defects in diameter of 1.0, 1.5, 2.0 and 3.0 mm were generated in the centre of the mouse masseter using a biopsy punch to determine the critical size for functional impairment. In the VML region, myogenesis was dampened but fibrogenesis was activated, as long with a reduction in the density of the neuromuscular junction and an increase in vascular density. Accordingly, persistent fibrosis was observed in the centre region of VML in all diameters. The 2.0 mm diameter was the critical threshold to masticatory function impairment after VML in the masseter. VML of 3.0 mm diameter led to a significant impact on nutrition intake and body weight gain. Autologous muscle graft effectively relieved the fibrosis and functional deficit after VML injury in the masseter. This model serves as a reliable tool in studying functional recovery strategies for orofacial muscle defects.
Topics: Animals; Mastication; Masseter Muscle; Mice; Disease Models, Animal; Male; Mice, Inbred C57BL; Muscle Development; Fibrosis
PubMed: 38356342
DOI: 10.1111/cpr.13610 -
Neurologia Medico-chirurgica Apr 2024Immediate postcraniotomy headache frequently occurs within the first 48 h after surgery. The mechanisms underlying immediate postcraniotomy headache are not yet fully...
Immediate postcraniotomy headache frequently occurs within the first 48 h after surgery. The mechanisms underlying immediate postcraniotomy headache are not yet fully understood, and effective treatments are not yet established. This study aimed to identify the factors associated with immediate postcraniotomy headache in patients who underwent clipping surgery with frontotemporal craniotomy and to examine the effects of these factors on postcraniotomy headache. A total of 51 patients were included in this study. Immediate postcraniotomy headache was defined as pain with numerical rating scale score ≥4 on postoperative day 7. Sixteen patients (31.4%) had immediate postcraniotomy headache. The headache-positive group had a higher incidence of preoperative analgesic use (50.0% vs. 5.7%, respectively, p < 0.001), increased temporal muscle swelling ratio (137.0%±30.2% vs. 112.5%±30.5%, respectively, p = 0.01), and higher postoperative analgesic use (12.9±5.8 vs. 6.7±5.2, respectively, p < 0.001) than the headache-negative group. The risk factors independently associated with immediate postcraniotomy headache were preoperative analgesic use and temporal muscle swelling by >115.15% compared with the contralateral side in the receiver operating characteristic analysis. Postcraniotomy headache was significantly more common in patients with preoperative analgesic use and temporal muscle swelling than in those without (p < 0.001 and p = 0.002, respectively). Altogether, patients with immediate postcraniotomy headache had greater preoperative analgesic use, greater temporal muscle swelling ratio, and higher postoperative analgesic use than those without. Thus, temporal muscle swelling is a key response to immediate postcraniotomy headache.
Topics: Humans; Temporal Muscle; Headache; Analgesics; Risk Factors; Craniotomy
PubMed: 38355127
DOI: 10.2176/jns-nmc.2023-0228 -
Cureus Feb 2024This study aimed to investigate whether there was a difference in the muscular activity of the masticatory muscles between patients with skeletal Class II and skeletal...
A Comparative Electromyographic Analysis of Masticatory Muscles Between Skeletal Class II and Skeletal Class I Malocclusion: A Cross-Sectional Study on a Syrian Population.
OBJECTIVES
This study aimed to investigate whether there was a difference in the muscular activity of the masticatory muscles between patients with skeletal Class II and skeletal Class I malocclusion.
MATERIALS AND METHODS
A cross-sectional study was conducted using a sample of 56 selected patients referred to the Department of Orthodontics and Dentofacial Orthodontics, Faculty of Dentistry at the University of Damascus, Damascus, Syria. An electromyographic device measured the myoelectric activity of the perioral muscles on patients in the two created groups: the skeletal Class I malocclusion group (n=28 patients) and the skeletal Class II malocclusion group (n=28 patients).
RESULTS
The study found a similarity in the muscular activity between the right and left sides within the same group, without significant differences between both sides for each muscle (P>0.05). The Class II group had significantly greater activity in the buccinator and digastric muscles than the Class I group (p<0.05). On the other hand, the Class I group had significantly greater activity in the orbicularis and mentalis muscles than the Class II group (P<0.05).
CONCLUSION
Patients with skeletal Class II malocclusion and skeletal Class I showed differences in muscular activity. The buccinator and digastric muscles were more active in skeletal Class II patients, while orbicularis oris and mentalis were less active. The temporalis and masseter muscles showed similar activity in both groups.
PubMed: 38343698
DOI: 10.7759/cureus.53960 -
Journal of Clinical Medicine Feb 2024The presented narrative review aims to present the impact of therapeutic methods on the masticatory muscle activity measured using surface electromyography (sEMG) in... (Review)
Review
Use of Surface Electromyography to Evaluate Effects of Therapeutic Methods on Masticatory Muscle Activity in Patients with Temporomandibular Disorders: A Narrative Review.
The presented narrative review aims to present the impact of therapeutic methods on the masticatory muscle activity measured using surface electromyography (sEMG) in patients with temporomandibular disorders (TMDs). Original interventional studies with baseline data for diagnosed TMD groups with full-text articles in English published in scientific journals in the last ten years were included in the evaluation process. The following narrative review considered only clinical, controlled, and randomized studies. Articles that included the following parameters were qualified for this review: adult participants, diagnosis of temporomandibular disorder, the presence of a musculoskeletal dysfunction, no other severe comorbidities, use of therapeutic interventions, and sEMG measurement before and after the intervention. Ten papers were accepted and analyzed for the final evaluation in the presented review. Several studies using surface electromyographic examination prove the effectiveness of various therapies to normalize the bioelectrical activity of the masticatory muscles, either reduction during rest or increase during a functional task in patients diagnosed with temporomandibular disorders. This narrative review shows the influence of manual and physical treatments on electromyographic masticatory muscle activity, including soft tissue mobilization, transcutaneous electrical nerve stimulation, low-level laser therapy, and moist heat therapy. Changes in masticatory muscle activity coincided with changes in TMD-associated pain and range of mandibular mobility.
PubMed: 38337614
DOI: 10.3390/jcm13030920 -
Heliyon Feb 2024This retrospective cohort study aimed to analyze volumes of craniomaxillofacial bone and masticatory muscles of young adults with bilateral idiopathic condylar...
OBJECTIVES
This retrospective cohort study aimed to analyze volumes of craniomaxillofacial bone and masticatory muscles of young adults with bilateral idiopathic condylar resorption.
METHODS
This was a retrospective cohort study of 84 adults with bilateral idiopathic condylar resorption (BCR) and 48 adults with normal temporal-mandibular joint (TMJ) matched for age and sex (mean age, 23.2 ± 3.6 years). The volumes of craniomaxillofacial bone and masticatory muscles, as well as intercondylar angle were measured. Unpaired t-tests and Pearson correlation tests were applied to analyze the data. Multivariable linear regression models were used to estimate the association between bilateral condylar volume and volumes of craniomaxillofacial bone and masticatory muscles adjusted for age, sex, and disc status.
RESULTS
Compared to the control group, the BCR group displayed significant decreased volumes of craniomaxillofacial bone (p < 0.001), craniomaxillofacial bone without mandible (p < 0.001), mandible (p < 0.001), mandible without mandibular condylar process (p < 0.001), bilateral masseter muscle (p < 0.001) and bilateral temporalis muscle (p < 0.001), as well as the intercondylar angle (p < 0.001). These variables were significantly correlated to the volume of mandibular condylar process (0.5< r < 0.8; p < 0.001). By linear regression analyses, significant associations were found for the bilateral condylar volume with craniomaxillofacial bone volume and mandible bone volume.
CONCLUSIONS
Young adults with BCR displayed smaller volumes of craniomaxillofacial skeleton and masticatory muscles, and smaller intercondylar angle than the normal patients. The craniofacial musculoskeletal volume and intercondylar angle are associated with mandibular condylar process volume.
PubMed: 38333825
DOI: 10.1016/j.heliyon.2024.e25037 -
Pilot and Feasibility Studies Feb 2024Temporomandibular disorders (TMD) are a collective term for pain and dysfunction of the masticatory muscles and the temporomandibular joints. The most common types of...
Transcutaneous auricular vagus nerve stimulation for the treatment of myoarthropatic symptoms in patients with craniomandibular dysfunction - a protocol for a randomized and controlled pilot trial.
BACKGROUND
Temporomandibular disorders (TMD) are a collective term for pain and dysfunction of the masticatory muscles and the temporomandibular joints. The most common types of TMD are pain-related, which may impact the psychological behavior and quality of life. Currently, the most popular methods for the treatment of TMD patients are occlusal splint therapy, often in combination with physical- and/or pharmacotherapy. However, due to the complexity of etiology, the treatment of chronic TMD remains a challenge. Recently, CE-certified systems for non-invasive VNS (transcutaneous auricular vagus nerve stimulation, taVNS) have become available and show positive effects in the treatment of chronic pain conditions, like migraine or fibromyalgia, with which TMD shares similarities. Therefore, it is the main purpose of the study to evaluate the feasibility of daily taVNS against chronic TMD and to assess whether there is an improvement in pain severity, quality of life, and kinetic parameters.
METHODS
This study is designed as a single-blinded, double-arm randomized controlled trial (RCT) in a 1:1 allocation ratio. Twenty adult patients with chronical TMD symptoms will be enrolled and randomized to stimulation or sham group. In the stimulation group, taVNS is performed on the left tragus (25 Hz, pulse width 250 µs, 28 s on/32 s off, 4 h/day). The sham group will receive no stimulation via a non-functional identical-looking electrode. Validated questionnaire data and clinical parameters will be collected at the beginning of the study and after 4 and 8 weeks. The compliance of a daily taVNS of patients with chronical TMD will be evaluated via a smartphone app recording daily stimulation time and average intensity. Additionally, the treatment impact on pain severity and quality of life will be assessed with different questionnaires, and the effect on the mandibular mobility and muscle activity will be analyzed.
DISCUSSION
This is the first clinical trial to assess the feasibility of taVNS in patients with chronic TMD symptoms. If taVNS improves the symptoms of TMD, it will be a significant gain in quality of life for these chronic pain patients. The results of this pilot study will help to determine the feasibility of a large-scale RCT.
TRIAL REGISTRATION
This study has been registered in the DRKS database (DRKS00029724).
PubMed: 38331976
DOI: 10.1186/s40814-024-01447-x -
Journal of Anatomy Jun 2024Anomaluromorpha is a particularly puzzling suborder of Rodentia. Endemic to Africa, this clade includes the extant genera Idiurus, Anomalurus, Zenkerella, and Pedetes....
Springhares, flying and flightless scaly-tailed squirrels (Anomaluromorpha, Rodentia) are the squirrely mouse: comparative anatomy of the masticatory musculature and its implications on the evolution of hystricomorphy in rodents.
Anomaluromorpha is a particularly puzzling suborder of Rodentia. Endemic to Africa, this clade includes the extant genera Idiurus, Anomalurus, Zenkerella, and Pedetes. These rodents present an hystricomorphous condition of the skull, characterized by a large infraorbital foramen, which evolved independently within the mouse-related clade over a span of approximately 57 million years. They exhibit a high disparity in craniomandibular and dental morphology that has kept their phylogenetic affinities disputed for a long time. Given the past significance of masticatory morphotypes in establishing the classification of Rodentia, we propose to explore variations in the masticatory apparatus of Anomaluromorpha in order to evaluate whether its related features can offer additional data for systematics and contribute to our understanding of the complexity of hystricomorphy. In order to do so, we used traditional dissection and diffusible iodine-based contrast-enhanced computed tomography (diceCT) to accurately describe and compare the anatomy of the specimens. We found that the muscle morphology displays clear differentiation among each anomaluromorph taxonomic unit. Specifically, the masseteric complex of Anomaluromorpha exhibits distinctive synapomorphies such as the infraorbital part of the zygomaticomandibularis muscle being separated into a rostral and orbital part and an absence of a posterior part of the zygomaticomandibularis. Additionally, the orbital portion of the infraorbital part originates from a well-marked ridge and fossa at the level of its area of origin on the anteromedial wall of the orbital cavity, a feature that is absent in other members of the mouse-related clade. This evident bony feature, among others, is strongly associated with muscular anatomy and can contribute to ascertaining the taxonomic status of extinct representatives of the clade. Finally, we showed that the hystricomorphy of Anomaluromorpha largely differs from those of Ctenohystrica and Dipodoidea and that the definition of this morphotype is complex and cannot be reduced simply to the size of the opening of the infraorbital foramen.
Topics: Animals; Masticatory Muscles; Biological Evolution; Sciuridae; Phylogeny; Skull; Mice
PubMed: 38318941
DOI: 10.1111/joa.14013 -
Cureus Jan 2024Background Masticatory Myofascial Pain Dysfunction Syndrome (MMPDS) is a musculoligamentous disorder that shares similarities with temporomandibular joint pain and...
Background Masticatory Myofascial Pain Dysfunction Syndrome (MMPDS) is a musculoligamentous disorder that shares similarities with temporomandibular joint pain and odontogenic pain. It manifests as dull or aching pain in masticatory muscles, influenced by jaw movement. Computer-aided drug design (CADD) encompasses various theoretical and computational approaches used in modern drug discovery. Molecular docking is a prominent method in CADD that facilitates the understanding of drug-bimolecular interactions for rational drug design, mechanistic studies & the formation of stable complexes with increased specificity and potential efficacy. The docking technique provides valuable insights into binding energy, free energy, and complex stability predictions. Aim The aim of this study was to use the docking technique for myosin inhibitors. Materials and methods Four inhibitors of myosin were chosen from the literature. These compound structures were retrieved from the Zinc15 database. Myosin protein was chosen as the target and was optimized using the RCSB Protein Data Bank. After pharmacophore modeling, 20 novel compounds were found and the SwissDock was used to dock them with the target protein. We compared the binding energies of the newly discovered compounds to those of the previously published molecules with the target. Results The results indicated that among the 20 molecules ZINC035924607 and ZINC5110352 exhibited the highest binding energy and displayed superior properties compared to the other molecules. Conclusion The study concluded that ZINC035924607 and ZINC5110352 exhibited greater binding affinity than the reported inhibitors of myosin. Therefore, these two molecules can be used as a potential and promising lead for the treatment of MMPDS and could be employed in targeted drug therapy.
PubMed: 38313945
DOI: 10.7759/cureus.51661 -
Journal of Anatomy Jun 2024Primate mandibular morphology is often associated with jaw functionality of the masticatory complex in the context of variation in diets. Recent research into the...
Primate mandibular morphology is often associated with jaw functionality of the masticatory complex in the context of variation in diets. Recent research into the disparities between the diet and jaw functionality in male and female hominoids is inconclusive and suggests that sexual dimorphism in the mandible may be influenced by external factors such as temporalis and masseter muscle morphology, which in turn may be influenced by sexual selection. As the muscles associated with mastication (i.e., the type of chewing exhibited by primates and other mammals) encompass the mandible as well as the neurocranium, including the sagittal crest among some individuals, this study investigates sex-specific associations between regions of the mandibular ramus and neurocranium associated with mastication in a dentally mature sample of Gorilla and Pongo. A total of four cranial and mandibular variables were measured in two Gorilla taxa (Gorilla gorilla gorilla and Gorilla beringei graueri) and one Pongo taxon (Pongo pygmaeus pygmaeus) (n = 220). For all three taxa, we investigate (a) whether the degree of sexual dimorphism in cranial regions associated with sagittal cresting (sagittal crest size (SCS) and temporalis muscle attachment area (TMAA)) is proportional to the degree of mandibular ramus area (MRA) and coronoid process height (CPH) sexual dimorphism, (b) whether there are sex differences in scaling relationships between TMAA and MRA, and (c) whether there are sex differences in the strength of association between TMAA and CPH. We show that for G. g. gorilla, variables associated with sagittal cresting show higher sexual dimorphism values than our two mandibular ramus variables, which is not the case for G. b. graueri or for P. p. pygmaeus. All three taxa show similar sex-specific scaling relationships between TMAA and MRA, where for males this relationship does not diverge from isometry, and for females there is a negative allometric relationship. Our findings also show intraspecific sex differences in allometric slopes between MRA and TMAA for all three taxa. Only G. g. gorilla shows a significant association between TMAA and CPH, which is observed in both sexes. Although there are some statistical associations between the cranial and mandibular regions associated with mastication, our results show that among male gorillas and orangutans, patterns of variation in the sagittal crest, TMAA, mandibular ramus and the coronoid process cannot be explained by the muscle attachment hypothesis alone. These findings have implications surrounding the associations between social behaviour and the morphology of the craniofacial complex.
Topics: Animals; Male; Female; Gorilla gorilla; Mandible; Sex Characteristics; Skull; Pongo; Mastication; Masticatory Muscles
PubMed: 38308581
DOI: 10.1111/joa.14018