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Objectives: This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars. Materials and methods: Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n = 30), and control group (n = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed. Results: The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC (p = 0.027) and EMA (p = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols (p < 0.05). Conclusions: Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars. Clinical relevance: The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function. [ABSTRACT FROM AUTHOR]

Background: Oral frailty, characterised by reduced oral function, is associated with systemic health issues in older adults. Although the criteria for diminished oral function often focus on motor and secretory abilities, texture perception also plays a crucial role in health due to its impact on food intake and palatability. Objective: This study aimed to explore the relationship between thickness discrimination ability (TDA) and oral motor and secretory functions in healthy young individuals. Methods: Twenty‐eight adults were assessed for texture perception using eight concentrations of aqueous xanthan gum solutions to determine TDA scores. Measurements of occlusal force, masticatory performance, tongue pressure, stimulated salivary flow rate and tongue–lip motor function were conducted. Spearman's correlation analysis was used to evaluate the relationship between TDA scores and oral functions. Participants were divided into high‐sensitivity and low‐sensitivity groups based on their TDA scores to compare oral function test results. Results: The TDA scores varied among the participants, with higher scores correlating with higher masticatory performance (r = 0.41, p <.05). Masticatory performance in the high‐sensitivity group was significantly higher than in the low‐sensitivity group (211.9 ± 59.2 mg/dL vs. 157.9 ± 43.0 mg/dL, p =.013), with no significant differences in other oral functions. Conclusion: Masticatory performance was correlated with TDA, suggesting a link between the selection function of mastication and thickness discrimination. These findings highlight the potential relevance of texture perception in oral function and indicate the need for further exploration, particularly in older adults with declining oral health. [ABSTRACT FROM AUTHOR]

Background: The noteworthy correlation between bite force and masticatory performance emphasizes its significance as a meaningful and objective method for assessing oral function. Furthermore, in the study of bruxism, the measurement of intraoral bite force assumes critical importance. Given the importance of assessing occlusal forces and bite force, this systematic review aims to assess the efficacy of wireless sensors in measuring these forces. Methods: The search methodology employed in this systematic review adhered to the guidelines outlined by PRISMA. The strategy involved the exploration of various databases, including PubMed/MEDLINE, SCOPUS and SCIELO. An assessment tool was employed to evaluate the bias risk and study quality. Results: This systematic review encompassed six prospective clinical studies involving a total of 89 participants. Wireless sensors for measuring occlusal forces and bite forces were predominantly employed in healthy adults or individuals with bruxism, along with children undergoing orthodontic treatment. All wireless sensors employed in the studies underwent validation and reproducibility assessments, affirming their reliability. The findings indicated that all wireless sensors exhibited efficacy in detecting occlusal forces and bite forces. Conclusion: Wireless sensors offer real‐time monitoring of occlusal and bite forces, aiding in understanding force distribution and identifying bruxism patterns. Despite limited studies on their application, these sensors contribute to evolving insights. Integration into clinical practice requires careful consideration of factors like calibration and patient compliance. Ongoing research is crucial to address limitations and enhance the efficacy of wireless sensors in measuring occlusal and bite forces and managing bruxism. [ABSTRACT FROM AUTHOR]

Background Objectives Methods Results Conclusions Electromyographic activity (EMG) of masticatory muscles during wakefulness is understudied. It is unclear if single channel ambulatory EMG devices are sensitive enough to detect masticatory muscle activity (MMA) during wakefulness.To compare the MMA of various oral tasks recorded with a single channel EMG device ((Grindcare4‐datalogger Prototype device) (GC4‐β)) and a conventional EMG (cEMG) device.EMG activity of 30 standardised oral tasks was recorded unilaterally from the masseter and anterior temporalis muscle in 24 healthy volunteers using GC4‐β and a cEMG device. To compare the EMG data, signal‐to‐noise ratios (SNR) were calculated as a way to normalise EMG activity across tasks. Analysis of variance was used to compare the SNR between the devices, muscles and oral tasks.SNR measured from GC4‐β was overall significantly higher than the cEMG device (p =.001). The SNR for maximum voluntary contraction (MVC) was significantly higher than all other tasks (p <.001). SNR for temporalis with GC4‐β was significantly higher for MVC, hard food, soft food, gum chewing (dominant side), rhythmic clenching and upper lip biting compared to the cEMG device (p <.021). The SNR for masseter with GC4‐β was significantly higher for hard food and gum chewing (dominant side), rhythmic clenching, rhythmic biting of an object and yawning compared to the cEMG device (p <.022).This study provides novel insight into the EMG patterns of numerous oral tasks enhancing knowledge of physiological differences between the masticatory muscles. Further, single channel EMG devices can effectively measure the EMG activity of various oral tasks during wakefulness. [ABSTRACT FROM AUTHOR]

Background: Temporomandibular disease (TMD) is commonly seen, and divers also experience pain in the temporomandibular joint (TMJ) or masticatory muscles. This article aims to provide a tool for diving physicians or medical professionals involved in diving medicine since jaw pain among divers is a pertinent subject and can be challenging to evaluate without some background in dentistry or maxillofacial surgery. Method: A basic algorithm was developed to provide a tool to differentiate jaw pains experienced by divers. Three brief case studies were developed, and five diving physicians were tasked with diagnosing the cases using the algorithm. Additionally, simple exercises and massage techniques that can benefit patients with TMD, particularly immediately after diving, are outlined. Results: All five diving physicians successfully diagnosed the cases using the algorithm. However, three of them were unable to diagnose the first case (disc luxation) without consulting the algorithm. Nevertheless, all physicians acknowledged the utility of the algorithm. Conclusions: Jaw pain in divers can stem from diverse causes, but effective treatment options exist. Our study findings provide valuable insights to assist diving physicians in making accurate diagnoses and guiding appropriate patient management, which may include referrals to specialists such as dentists, maxillofacial surgeons, or orthodontists. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objectives: To present an interdisciplinary case treated with a surgery‐first orthognathic approach, followed by orthodontic and prosthodontic treatment. Clinical Considerations: After an accurate pre‐operative virtual planning, a young patient with skeletal class II, retrognathia, and an anterior open bite was treated with bimaxillary orthognathic surgery without pre‐surgical orthodontic decompensation. Orthodontic treatment was carried out post‐operatively. The treatment was completed with a prosthodontic phase to improve the final esthetic outcome of the smile. Conclusions: A surgery‐first approach allowed to achieve esthetic and functional results in a reduced treatment duration that remained stable over the course of 1 year. The outcomes were consistent with prior research in terms of advantages brought by following an accurately planned surgery‐first protocol. Nevertheless, longer‐term follow‐up was required to evaluate the treatment stability. Clinical Significance: An accurately planned surgery‐first approach significantly helped in shortening the duration of the treatment, while providing a stable, functional, and esthetic solution to the patient's problems. [ABSTRACT FROM AUTHOR]

Temporomandibular disorders (TMDs) are a heterogeneous group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles, and associated structures. Mesenchymal stromal/stem cells (MSCs) have emerged as a promising therapy for TMJ repair. This systematic review aims to consolidate findings from the preclinical animal studies evaluating MSC-based therapies, including MSCs, their secretome, and extracellular vesicles (EVs), for the treatment of TMJ cartilage/osteochondral defects and osteoarthritis (OA). Following the PRISMA guidelines, PubMed, Embase, Scopus, and Cochrane Library databases were searched for relevant studies. A total of 23 studies involving 125 mice, 149 rats, 470 rabbits, and 74 goats were identified. Compliance with the ARRIVE guidelines was evaluated for quality assessment, while the SYRCLE risk of bias tool was used to assess the risk of bias for the studies. Generally, MSC-based therapies demonstrated efficacy in TMJ repair across animal models of TMJ defects and OA. In most studies, animals treated with MSCs, their derived secretome, or EVs displayed improved morphological, histological, molecular, and behavioral pain outcomes, coupled with positive effects on cellular proliferation, migration, and matrix synthesis, as well as immunomodulation. However, unclear risk in bias and incomplete reporting highlight the need for standardized outcome measurements and reporting in future investigations. [ABSTRACT FROM AUTHOR]

Background: Skeletal craniofacial morphology can be influenced by changes in masticatory muscle function, which may also change the functional profile of the muscles. Objectives: To investigate the effects of age and functional demands on the expression of Myosin Heavy‐Chain (MyHC) isoforms in representative jaw‐closing and jaw‐opening muscles, namely the masseter and digastric muscles respectively. Methods: Eighty‐four male Wistar rats were divided into four age groups, namely an immature (n = 12; 4‐week‐old), early adult (n = 24; 16‐week‐old), adult (n = 24; 26‐week‐old) and mature adult (n = 24; 38‐week‐old) group. The three adult groups were divided into two subgroups each based on diet consistency; a control group fed a standard (hard) diet, and an experimental group fed a soft diet. Rats were sacrificed, and masseter and digastric muscles dissected. Real‐time quantitative polymerase chain reaction was used to compare the mRNA transcripts of the MyHC isoforms—Myh7 (MyHC‐I), Myh2 (MyHC‐IIa), Myh4 (MyHC‐IIb) and Myh1 (MyHC‐IIx)—of deep masseter and digastric muscles. Results: In the masseter muscle, hypofunction increases Myh1 (26, 38 weeks; p <.0001) but decreases Myh4 (26 weeks; p =.046) and Myh2 (26 weeks; p <.0001) expression in adult rats. In the digastric muscle, hypofunction increases Myh1 expression in the mature adult rats (38 weeks; p <.0001), while Myh2 expression decreases in adult rats (26 weeks; p =.021) as does Myh4 (26 weeks; p =.001). Myh7 expression is increased in the digastric muscle of mature adult rats subjected to hypofunction (38 weeks; p = <.0001), while it is very weakly expressed in the masseter. Conclusion: In jaw‐opening and jaw‐closing muscles, differences in myosin expression between hard‐ and soft‐diet‐fed rats become evident in adulthood, suggesting that long‐term alteration of jaw function is associated with changes in the expression of MyHC isoforms and potential fibre remodelling. This may give insight into the role of function on masticatory muscles and the resultant craniofacial morphology. [ABSTRACT FROM AUTHOR]

Background: Graftless sinus floor augmentation shows good results in bone gain, radiology and implant survival. Clinically, this technique can be recommended as an alternative to conventional procedures using augmentation materials. Objectives: This study aims to assess masticatory performance, masticatory ability and patient satisfaction after graftless sinus floor augmentation. Methods: The study group consisted of patients who had received a graftless sinus lift procedure in a split‐mouth design and was compared to patients with maxillary implant‐supported overdentures without augmentation and a natural dentition group. To assess objective masticatory performance, the mixing ability test was performed. Three questionnaires were used to assess patient reported outcomes related to mastication and patient satisfaction. Results: Each group included ten patients. Both the graftless sinus lift group and the edentulous control group had a worse masticatory performance compared to the natural dentition group. Masticatory ability, measured by patient reported outcomes, was not different between the graftless sinus floor augmentation group and implant‐retained overdentures group without augmentation, but the natural dentition group showed better results. Thereby, the better the masticatory performance in patients with a graftless sinus membrane elevation the better the patient satisfaction for 'prosthesis', 'appearance of prostheses', 'speech' and 'mastication and eating'. Conclusions: Patients with implant‐supported overdentures show inferior masticatory function compared to those with natural dentition. There were no significant differences in masticatory performance between patients with implant‐retained overdentures, with or without graftless augmentation. The decision on the preferred procedure should consider additional factors such as anatomical, surgical‐technical aspects and patient's preferences. [ABSTRACT FROM AUTHOR]

Background: Mandibular reconstruction patients often suffer abnormalities in the mandibular kinematics. In silico simulations, such as musculoskeletal modelling, can be used to predict post‐operative mandibular kinematics. It is important to validate the mandibular musculoskeletal model and analyse the factors influencing its accuracy. Objectives: To investigate the jaw opening‐closing movements after mandibular reconstruction, as predicted by the subject‐specific musculoskeletal model, and the factors influencing its accuracy. Methods: Ten mandibular reconstruction patients were enrolled in this study. Cone‐beam computed tomography images, mandibular movements, and surface electromyogram signals were recorded preoperatively. A subject‐specific mandibular musculoskeletal model was established to predict surgical outcomes using patient‐averaged muscle parameter changes as model inputs. Jaw bone geometry was replaced by surgical planning results, and the muscle insertion sites were registered based on the non‐rigid iterative closest point method. The predicted jaw kinematic data were validated based on 6‐month post‐operative measurements. Correlations between the prediction accuracy and patient characteristics (age, pathology and surgical scope) were further analysed. Results: The root mean square error (RMSE) for lower incisor displacement was 31.4%, and the error for peak magnitude of jaw opening was 4.9 mm. Age, post‐operative infection and radiotherapy influenced the prediction accuracy. The amount of masseter detachment showed little correlation with jaw opening. Conclusion: The mandibular musculoskeletal model successfully predicted short‐range jaw opening functions after mandibular reconstruction. It provides a novel surgical planning method to predict the risk of developing trismus. [ABSTRACT FROM AUTHOR]

Background: Large horizontal maxillary overjet (overjet) is associated with reduced bite force (BF) and number of contacts, which influence the chewing effectivity (CE). Oral health, oro‐facial function (OF) and malocclusion have great impact on psychological well‐being and quality of life (QoL). Objectives: The aims of the study were to examine OF, temporomandibular disorders (TMD), BF, CE, QoL and well‐being in children and adolescents with large overjet. Methods: The study was a case–control study including healthy children with large overjet in the study group compared to a control group of healthy children with neutral occlusion, all 9–14 years old. OF was examined by use of Nordic Orofacial Test‐Screening (NOT‐S), Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and registration of morphological and functional occlusion. QoL and well‐being were examined using KIDSCREEN‐10 and Strengths and Difficulties Questionnaire. Results: The study and control groups included 37 and 32 participants, respectively. Significantly increased NOT‐S score (p <.001) and reduced BF (p =.011), numbers of contacts (p <.001) and CE (p =.005) were found in the study group. BF, numbers of contacts and CE were negatively associated with erupting canines and premolars. No significant difference was found in age, gender, dental eruption, TMD diagnosis or QoL between the groups. Significantly increased emotional symptoms (p =.007), hyperactivity (p =.043) and total difficulties score (p =.009) were found in the study group. Conclusion: The study group showed higher NOT‐S score and reduced BF, number of contacts and CE. No difference in QoL were found between the groups, although reduced well‐being and increased emotional symptoms, hyperactivity and total difficulties were found in the study group. [ABSTRACT FROM AUTHOR]

Background: Jaw clenching improves dynamic reactive balance on an oscillating platform during forward acceleration and is associated with decreased mean sway speed of different body regions. Objective: It is suggested that jaw clenching as a concurrent muscle activity facilitates human motor excitability, increasing the neural drive to distal muscles. The underlying mechanism behind this phenomenon was studied based on leg and trunk muscle activity (iEMG) and co‐contraction ratio (CCR). Methods: Forty‐eight physically active and healthy adults were assigned to three groups, performing three oral motor tasks (jaw clenching, tongue pressing against the palate or habitual lower jaw position) during a dynamic one‐legged stance reactive balance task on an oscillating platform. The iEMG and CCR of posture‐relevant muscles and muscle pairs were analysed during platform forward acceleration. Results: Tongue pressing caused an adjustment of co‐contraction patterns of distal muscle groups based on changes in biomechanical coupling between the head and trunk during static balancing at the beginning of the experiment. Neither iEMG nor CCR measurement helped detect a general neuromuscular effect of jaw clenching on the dynamic reactive balance. Conclusion: The findings might indicate the existence of robust fixed patterns of rapid postural responses during the important initial phases of balance recovery. [ABSTRACT FROM AUTHOR]

Purpose: Visual impairment, hearing impairment, and masticatory discomfort each influence quality of life (QoL). However, little is known regarding the impact of their coexistence on QoL. Therefore, we aimed to investigate the influence of the coexistence of visual impairment, hearing impairment, and masticatory discomfort on QoL among middle-aged adults aged 40-64. Methods: This study involved a secondary data analysis utilizing the data from years 1 and 2 of the eighth Korea National Health and Nutrition Examination Survey. To evaluate the influence of the coexistence of visual impairment, hearing impairment, and masticatory discomfort on QoL, we conducted a complex sample hierarchical multiple regression analysis. Results: When visual impairment, hearing impairment, and masticatory discomfort coexisted, the QoL was significantly lower than in individuals without any of these conditions. Conclusion: The coexistence of visual impairment, hearing impairment, and masticatory discomfort was negatively correlated with QoL. Therefore, it is important to prepare for old age through appropriate health management during middle age. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to analyse morphological parameters related to the bite apparatus in representatives of seven families of captive animals. Thirty-three measurements were taken of the skull, mandible, and surfaces of the masseter and temporalis muscles. Some were used to calculate the bite force on the maxillary canine and molar teeth. A high correlation between bite force and animal size was confirmed. The bending strength of the upper canines was determined using their lateromedial and anteroposterior dimensions. The aim of this study was to analyse the bite forces of seven species from three carnivore families: Canidae, Felidae, and Ursidae. The material consisted of complete, dry crania and mandibles. A total of 33 measurements were taken on each skull, mandible, temporomandibular joint, and teeth. The area of the temporalis and masseter muscles was calculated, as was the length of the arms of the forces acting on them. Based on the results, the bite force was calculated using a mathematical lever model. This study compared the estimated areas of the masticatory muscles and the bending strength of the upper canines among seven species. A strong correlation was found between cranial size and bite force. The results confirmed the hypothesis that the weight of the animal and the size of the skull have a significant effect on the bite force. [ABSTRACT FROM AUTHOR]

Background: Botulinum toxin type A (BTX‐A) is increasingly used to manage painful temporomandibular disorders (TMD). However, the effect of BTX‐A on muscular TMD remains unclear. Objective: To assess the efficacy, safety and optimal dose of BTX‐A for treating TMD. Methods: We conducted systematic literature searches in MEDLINE, Embase, Web of Science, ClinicalTrials.gov and Cochrane Library until March 2023. We extracted data from randomized controlled trials (RCTs) that evaluated the efficacy and safety of BTX‐A in treating muscular TMD. We performed a meta‐analysis using a random‐effects model. Results: Fifteen RCTs involving 504 participants met the inclusion criteria. BTX‐A was significantly more effective than placebo in reducing pain intensity, as measured on a 0–10 scale, at 1 month (MD [95% CI] = −1.92 [−2.87, −0.98], p <.0001) and 6 months (MD [95% CI] −2.08, [−3.19 to −0.98]; p =.0002). A higher dosage of BTX‐A (60–100 U bilaterally) was associated with a greater reduction in pain at 6 months (MD [95% CI] = −2.98 [−3.52, −2.44]; p <.001). BTX‐A also resulted in decreased masseter muscle intensity (μV) (MD [95% CI] = −44.43 [−71.33, −17.53]; p =.001) at 1 month and occlusal force (kg) at 3 months (MD [95% CI] = −30.29 [−48.22 to −12.37]; p =.0009). There was no significant difference in adverse events between BTX‐A and placebo. Conclusions: BTX‐A is a safe and effective treatment for reducing pain and improving temporomandibular muscle and joint function in muscular TMD patients. A bilateral dose of 60–100 U might be an optimal choice for treating muscular TMD pain. [ABSTRACT FROM AUTHOR]

Background: Unbalanced alterations of temporomandibular joint morphology were associated with unilaterally masticatory habits. Objective: This study aimed to investigate the effect of unilateral mastication on the remodelling of the temporomandibular joint using dynamic joint space. Methods: Twelve volunteers with non‐maxillofacial deformity and healthy temporomandibular joints were recruited. The 3D models of the mandible and the maxilla were reconstructed according to computed tomography. The subjects were asked to masticate French fries and peanuts unilaterally, which was recorded by a 3D motion capture system. The dynamic joint space during unilateral mastication was analysed. Results: During early closure, the joint space reduction on the non‐masticatory side was significantly greater than on the masticatory side (p <.05). During later closure, the joint space reduction on the non‐masticatory side was significantly lower than that on the masticatory side (p <.05). The difference in joint space reduction between both sides was greater than the French fries while masticating the peanuts. Conclusions: Unilateral mastication resulted in a different major pressure area on the bilateral TMJs. Therefore, unilateral mastication might be an essential factor in the bilateral asymmetrical remodelling of the TMJ. [ABSTRACT FROM AUTHOR]

Background: Temporomandibular joint disorders (TMDs) are a variety of conditions that affect different parts of the temporomandibular joints (TMJ) and can cause orofacial pain and functional impairment. This study aims to investigate dental practitioners' knowledge and management of Temporomandibular Joint Disorders (TMDs), particularly their knowledge of the role physical therapy plays in TMD treatment. Methods: A mixed-methods approach was adopted to provide a comprehensive view of current knowledge, management practices, and attitudes toward collaboration among dental practitioners in treating TMD. Data were collected from a convenience sample of 335 dentists in Karachi using a detailed questionnaire to assess their knowledge of the role of physical therapy in the treatment of TMD. Twenty dentists were chosen for face-to-face, in-depth interviews to explore their experiences and challenges in managing TMDs based on their responses to the administered questionnaire. Results: The cumulative quantitative and qualitative findings of the study revealed a landscape marked by individualized approaches to referral practices and significant gaps in interdisciplinary collaboration. Most practitioners holding a bachelor's degree predominantly used medication (65.2%) and cause-specific treatment (65.3%) for TMD treatment. Thematic analysis of clinical efficacy and practitioner challenges in managing TMD revealed significant issues faced by dental professionals. Conclusions: The study successfully validated a questionnaire to understand dental practitioners' knowledge regarding physical therapy in TMD treatment. The study identified significant gaps in knowledge and a lack of collaboration between dentists and physiotherapists. The limited referral practices highlighted in the study, along with insights from dentist interviews, emphasize the need for improved interdisciplinary approaches to managing TMDs within dental practice. [ABSTRACT FROM AUTHOR]

Background: This study aims to analyze to what extent patients with Marfan syndrome (MFS) are affected by temporomandibular disorders (TMD) and its impact on oral health-related quality of life (OHRQoL). To collect data, an online questionnaire was created to recruit participants from Germany, Austria, and Switzerland through social media and support groups. The questionnaire consists of free-text questions, the German versions of the Oral Health Impact Profile (OHIP-G14), the Depression Anxiety Stress Scale (DASS), and the Graded Chronic Pain Status (GCPS). Results: A total of 76 participants with diagnosed MFS were included. Of these, 65.8% showed TMD symptoms, the most common being pain or stiffness of the masticatory muscles in the jaw angle (50.0%). Only 14.5% of the participants were already diagnosed with TMD. Of the participants with an increased likelihood of a depression disorder, 76.9% showed TMD symptoms. Of those with a critical score for an anxiety disorder, 90.9% showed TMD symptoms. 73.3% of participants with TMD symptoms reached the critical score for a stress disorder. TMD symptoms were associated with a higher risk for chronic pain. In the median, participants with TMD showed statistically notably higher OHIP-G14 scores than participants without TMD (11.5 [IQR 17] vs. 1 [IQR 3] points, p ≤ 0.001). Conclusion: TMD symptoms had a noticeable impact on OHRQoL in patients with MFS, i.e., chronic pain and psychological impairment. TMD seems underdiagnosed, and more research is needed to prevent the associated chronification of pain and psychological burden to improve the OHRQoL. [ABSTRACT FROM AUTHOR]

This study used ultrasonography to compare the thickness and cross-sectional area of the masticatory muscles in patients with temporomandibular joint arthralgia and investigated the differences according to sex and the co-occurrence of headache attributed to temporomandibular disorders (HATMD). The observational study comprised 100 consecutive patients with TMJ arthralgia (71 females and 29 males; mean age, 40.01 ± 17.67 years) divided into two groups: Group 1, including 86 patients with arthralgia alone (60 females; 41.15 ± 17.65 years); and Group 2, including 14 patients with concurrent arthralgia and HATMD (11 females; 33.00 ± 16.72 years). The diagnosis of TMJ arthralgia was based on the diagnostic criteria for temporomandibular disorders. The parameters of the masticatory muscles examined by ultrasonography were subjected to statistical analysis. The pain area (2.23 ± 1.75 vs. 5.79 ± 2.39, p-value = 0.002) and visual analog scale (VAS) score (3.41 ± 1.82 vs. 5.57 ± 12.14, p-value = 0.002) were significantly higher in Group 2 than in Group 1. Muscle thickness (12.58 ± 4.24 mm) and cross-sectional area (4.46 ± 2.57 cm2) were larger in the masseter muscle than in the other three masticatory muscles (p-value < 0.001). When examining sex-based differences, the thickness and area of the masseter and lower temporalis muscles were significantly larger in males (all p-value < 0.05). The area of the masseter muscle (4.67 ± 2.69 vs. 3.18 ± 0.92, p-value = 0.004) and lower temporalis muscle (3.76 ± 0.95 vs. 3.21 ± 1.02, p-value = 0.049) was significantly smaller in Group 2 than in Group 1. An increase in VAS was significantly negatively correlated with the thickness of the masseter (r = − 0.268) and lower temporalis (r = − 0.215), and the cross-sectional area of the masseter (r = − 0.329) and lower temporalis (r = − 0.293). The masseter and lower temporalis muscles were significantly thinner in females than in males, and their volumes were smaller in patients with TMJ arthralgia and HATMD than in those with TMJ arthralgia alone. HATMD and decreased masseter and lower temporalis muscle volume were associated with increased pain intensity. [ABSTRACT FROM AUTHOR]

This systematic review answers the question: "Does occlusal appliance use influence masticatory muscle function of dentate individuals with sleep bruxism?". The literature search included six databases, grey literature, and manual search for articles. Randomized and non‐randomized clinical trials were included comparing muscle function of sleep bruxers before and after receiving occlusal appliances. Risk of bias was assessed with risk of bias assessment for randomized and non‐randomized clinical trials tool. Twelve studies, three represent randomized clinical trials, were included. Risk of bias was considered low, moderate, or serious. Meta‐analyses indicated that soft and hard appliances did not influence muscle activity and bite force of bruxers. Qualitative analysis showed that occlusal appliance use did not influence masticatory performance and muscle volume. However, it was effective in reducing tongue force. Certainty of evidence was considered very low for muscle activity when evaluated with hard appliances, and for bite force evaluated with both appliance materials. Low certainty of evidence was observed for muscle activity with soft appliances. Based on the findings of this meta‐analysis, occlusal appliances do not affect masticatory muscle function of sleep bruxers. Regardless of appliance material, the activity of masseter and temporal, and bite force of sleep bruxers was not influenced. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present clinical study was to compare the Ricketts and Steiner cephalometric analysis obtained by two experienced orthodontists and artificial intelligence (AI)‐based software program and measure the orthodontist variability. Materials and Methods: A total of 50 lateral cephalometric radiographs from 50 patients were obtained. Two groups were created depending on the operator performing the cephalometric analysis: orthodontists (Orthod group) and an AI software program (AI group). In the Orthod group, two independent experienced orthodontists performed the measurements by performing a manual identification of the cephalometric landmarks and a software program (NemoCeph; Nemotec) to calculate the measurements. In the AI group, an AI software program (CephX; ORCA Dental AI) was selected for both the automatic landmark identification and cephalometric measurements. The Ricketts and Steiner cephalometric analyses were assessed in both groups including a total of 24 measurements. The Shapiro–Wilk test showed that the data was normally distributed. The t‐test was used to analyze the data (α = 0.05). Results: The t‐test analysis showed significant measurement discrepancies between the Orthod and AI group in seven of the 24 cephalometric parameters tested, namely the corpus length (p = 0.003), mandibular arc (p < 0.001), lower face height (p = 0.005), overjet (p = 0.019), and overbite (p = 0.022) in the Ricketts cephalometric analysis and occlusal to SN (p = 0.002) and GoGn‐SN (p < 0.001) in the Steiner cephalometric analysis. The intraclass correlation coefficient (ICC) between both orthodontists of the Orthod group for each cephalometric measurement was calculated. Conclusions: Significant discrepancies were found in seven of the 24 cephalometric measurements tested between the orthodontists and the AI‐based program assessed. The intra‐operator reliability analysis showed reproducible measurements between both orthodontists, except for the corpus length measurement. Clinical Significance: The artificial intelligence software program tested has the potential to automatically obtain cephalometric analysis using lateral cephalometric radiographs; however, additional studies are needed to further evaluate the accuracy of this AI‐based system. [ABSTRACT FROM AUTHOR]

The current study aims to differentiate, morphologically, between the masticatory muscles in black-tip sharks and shovelnose ray fish, which control the opening and closure of jaws. This work was applied to four specimens of each species, obtained from the Red Sea in Suez. Anatomical dissection was conducted on the cephalic region is order to expose the musculature. The obtained results illustrate each muscle's position, origin, and insertion. The common muscles involved in the feeding of both species were the muscles of mandibular arch: adductor mandibulae, levator palatoquadrati, while the muscles of hyoid arch were levator hyomandibulae, also the hypobranchial arch contained coracomandibularis, coracohyoideus, and coracoarcualis. All muscles of the jaws are responsible for the abduction of mouth except Adductor mandibulae M, Intermandibularis M. involved in closing the mouth, in addition, Preorbitalis M. assists in protruding of upper jaw. [ABSTRACT FROM AUTHOR]

Background: The impact of treatments on completely edentulous individuals on masticatory performance (MP), oral health‐related quality of life (OHRQoL), nutritional status (NS) and socio‐economic profile (SP) is unclear in the literature. Objective: To compare the MP, OHRQoL, NS and SP of totally edentulous elderly users of bimaxillary complete dentures (CD) and users of lower implant‐supported fixed complete dentures (IFCD). Methods: Forty participants were allocated into groups according to rehabilitation treatment (n = 20): bimaxillary CD (G1) and lower IFCD, and upper CD (G2). The evaluation of MP used almonds by the method of sieves. Four questionnaires (Geriatric Oral Health Assessment Index–GOHAI and Oral Health Impact Profile Edent–OHIP‐Edent, Brazilian Economic Classification Criteria–ABEP and Mini Nutritional Assessment‐MNA) were applied to assess the OHRQoL, SP and NS of the elderly, respectively. After evaluating the statistical assumptions, the Mann–Whitney (α =.05) test was applied to compare the groups regarding MP, OHRQoL, NS and SP. Spearman's correlation (α =.05) was performed to verify the correlation between the MP, the OHRQoL and the NS of the participants. Results: G2 showed better MP (p <.05) in all masticatory cycles, OHRQoL (p <.05) and NS than the G1. However, the participants' self‐perception of oral health did not differ between groups (p <.05). A moderate negative correlation was found between MP and OHRQoL for 40 masticatory cycles (r2 = −0.513; p =.001). Conclusion: Individuals rehabilitated with IFCD had a higher average monthly family income and achieved superior behaviour in MP and OHRQoL, in addition to lower risks of malnutrition when compared to individuals using bimaxillary CD. [ABSTRACT FROM AUTHOR]

Periodontitis is a widespread oral disease accompanied by uncontrolled inflammation‐related tissue destruction. Periodontitis is related to various factors. Among them, occlusal trauma can aggravate the severity of periodontitis and has been attracting a great deal of attention. We systematically searched PubMed and Web of Science databases for related articles. Keywords for the search were "mechanical force", "mechanical stress", "occlusal trauma" and "periodontitis". This review focuses on the effect of mechanical forces on periodontitis and discusses the possible pivotal targets participating in this process. We elucidated and summarized 21 articles that reported on our topic. Several biological processes and pathways that participate in enhancing the inflammatory response to mechanical stress have been studied, including the regulation of osteogenesis and osteoclastic resorption balance, Yes‐associated protein signaling, induction of collagen destruction, and regulation of programmed cell death. Mechanical force enhances the process of periodontitis in multiple ways. However, currently, no studies have further examined its underlying mechanism. Understanding the specific roles of mechanical forces may assist in the treatment of periodontitis with traumatic occlusal trauma. [ABSTRACT FROM AUTHOR]

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = − 1.018, 95% confidence interval [CI] − 1.855 to − 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = − 0.201, 95% CI − 0.299 to − 0.103, p = 0.011), increased age (B = − 0.003, 95% CI − 0.005 to 0.000, p = 0.038), and muscle stiffness (B = − 1.373, 95% CI − 2.369 to − 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD. [ABSTRACT FROM AUTHOR]

Surface electromyography (sEMG) is a technique for measuring and analyzing the electrical signals of muscle activity using electrodes placed on the skin's surface. The aim of this paper was to outline the history of the development and use of surface electromyography in dentistry, to show where research and technical solutions relating to surface electromyography currently lie, and to make recommendations for further research. sEMG is a diagnostic technique that has found significant application in dentistry. The historical section discusses the evolution of sEMG methods and equipment, highlighting how technological advances have influenced the accuracy and applicability of this method in dentistry. The need for standardization of musculoskeletal testing methodology is highlighted and the needed increased technical capabilities of sEMG equipment and the ability to specify parameters (e.g., sampling rates, bandwidth). A higher sampling rate (the recommended may be 2000 Hz or higher in masticatory muscles) allows more accurate recording of changes in the signal, which is essential for accurate analysis of muscle function. Bandwidth is one of the key parameters in sEMG research. Bandwidth determines the range of frequencies effectively recorded by the sEMG system (the recommended frequency limits are usually between 20 Hz and 500 Hz in masticatory muscles). In addition, the increased technical capabilities of sEMG equipment and the ability to specify electromyographic parameters demonstrate the need for a detailed description of selected parameters in the methodological section. This is necessary to maintain the reproducibility of sEMG testing. More high-quality clinical trials are needed in the future. [ABSTRACT FROM AUTHOR]

Background: The trigeminal nerve is a mixed cranial nerve responsible for the motor innervation of the masticatory muscles and the sensory innervation of the face, including the nasal cavities. Through its nasal innervation, we perceive sensations, such as cooling, tingling, and burning, while the trigeminal system mediates the perception of airflow. However, the intranasal trigeminal system has received little attention in the clinical evaluation of patients with nasal pathology. Summary: Testing methods that enable the clinical assessment of intranasal trigeminal function have recently been developed. This study aims to present the current clinical methods that can be utilised in everyday practice, as described in the literature. These methods include four assessment techniques: (1) the quick screening test of trigeminal sensitivity involves patients rating the intensity of ammonium vapour presented in a lipstick-like container. (2) The lateralisation test requires subjects to identify which nasal cavity is being stimulated by a trigeminal stimulus, such as eucalyptol or menthol, while the other side receives an odourless stimulus. (3) The trigeminal sticks test evaluates the trigeminal function similarly to the olfactory function using sticks filled with trigeminal stimulant liquids. (4) The automated CO2 stimulation device is used for measuring trigeminal pain thresholds, utilising intranasal CO2 stimuli to define the pain threshold. Key Messages: Assessing intranasal trigeminal function clinically may prove useful in evaluating rhinology patients, particularly those who encounter nasal obstruction without anatomical blockage and those experiencing olfactory disorders with suspected trigeminal dysfunction. Despite their limitations, the presented methods may provide useful information about nasal patency, chemosensitivity, and pain sensation in the daily clinical practice of such patients, leading to better therapeutic decisions. [ABSTRACT FROM AUTHOR]

Aim: To evaluate oral frailty features present in hospitalized older patients with aspiration pneumonia. Methods: We enrolled hospitalized patients aged ≥50 years and classified them into three groups: the community‐acquired, aspiration, and non‐community‐acquired pneumonia groups. Oral frailty was defined as meeting three or more criteria from the following: choking, and decreased occlusal force, masticatory function, tongue–lip motor function, tongue pressure, and tongue pressure during swallowing. Results: Of 168 patients enrolled, the incidence of aspiration pneumonia was 23.9% (17/71) in patients admitted with pneumonia as the primary diagnosis. The occlusal force and masticatory function were significantly poorer and tongue pressure and tongue pressure during swallowing were significantly lower in the aspiration pneumonia group than in the other two groups. A higher number of chronic comorbidities, poor oral health, and lower tongue pressure during swallowing were significantly associated with aspiration pneumonia. A tongue pressure during swallowing of <10.32 kPa might be a cutoff point for predicting the risk of aspiration pneumonia. Conclusions: Hospitalized patients aged ≥50 years with multiple comorbidities, poor oral hygiene, and oral frailty during swallowing are at a higher risk of developing aspiration pneumonia, especially when their tongue pressure during swallowing is <10.32 kPa. Aspiration pneumonia is a preventable disease. Healthcare professionals should incorporate tongue pressure measurements or other screening tools into routine clinical practice to facilitate the early detection of this condition and intervention. Geriatr Gerontol Int 2024; 24: 351–357. [ABSTRACT FROM AUTHOR]

Background: The evaluation of muscle pain and sensitivity by manual palpation is an important part of the clinical examination in patients with myalgia. However, the effects of clinical experience and visual feedback on palpation of the masticatory muscles with or without a palpometer are not known. Objective: To estimate the effects of clinical experience and visual feedback on the accuracy of palpation in standardized settings. Methods: Thirty‐two dentists (age 35 ± 11 years) classified as either specialists (n = 16) or generalists (n = 16) participated in this experiment. All dentists were instructed to target force levels of 500‐ or 1000‐gf, as determined on an electronic scale using either standardized palpometers or manual palpation (MP). All dentists participated in four different tests: MP, MP with visual feedback (MPVF), palpometer (PAL) and PAL with visual feedback (PALVF). Actual force values for each type of palpation from 0 to 2, 2 to 5 and 0 to 5 s were analysed by calculating target force level. Results: The relative differences during 2–5 and 0–5 s with 1000 gf were significantly lower for generalists than for specialists (p <.05). In generalists and specialists, the coefficients of variation and the relative differences during 2–5 s were significantly lower for PAL and PALVF than for MP (p <.05). Conclusions: These findings suggest that the use of a palpometer, but not clinical experience with palpation of masticatory muscles, increases the accuracy of palpation, and ≥2 s of palpation with a palpometer is optimal for masticatory muscles. [ABSTRACT FROM AUTHOR]

Background: Occlusal interferences lead to changes in mandibular kinematics to compensate and improve function. However, the effects of different types of eccentric disturbance on the comminution capacity are not known. Objective: To determine the immediate effect of eccentric occlusal interferences on masticatory performance. Methods: This crossover clinical trial included 12 healthy dentate subjects aged 25.2 ± 3.3 years who were randomly submitted to seven types of occlusal interference: unilateral and bilateral laterotrusive and mediotrusive, protrusive, dummy and control (no interference). The interference forms were planned in a semi‐adjustable articulator, fabricated with composite resin and adhered to the mandibular first molars such that subjects' maximum intercuspation was maintained. Masticatory performance and the chewing rate during 20 cycles were evaluated during subjects' comminution of silicone test food under one interference condition per test day; the multiple sieve method was applied to the comminuted particles. The interference was removed upon test completion, and a 1‐week washout period was applied between tests. Results: Comminuted median particle sizes were larger under unilateral (4.94 ± 0.41 mm) and bilateral (4.81 ± 0.49 mm) laterotrusive, bilateral mediotrusive (4.65 ± 0.50 mm) and protrusive (4.83 ± 0.54 mm) interferences (p <.05) than under the control (4.01 ± 0.52 mm) and dummy (4.18 ± 0.58 mm) conditions (p <.05). Only unilateral and bilateral laterotrusive interferences narrowed the comminuted particle size dispersion (p <.05). The chewing rate did not differ among conditions (p =.1944). Conclusion: Artificial eccentric interferences had an immediate adverse effect on masticatory performance by resulting in larger comminuted particles. Clinical trial registration: Brazilian Registry of Clinical Trials (RBR‐8g5zfg8). [ABSTRACT FROM AUTHOR]

Background: Masseter muscle activity during wakefulness may be associated with temporomandibular disorder (TMD)‐related symptoms, psychosocial status and pain‐related disability; however, this relationship is unclear. Objectives: This study aimed to determine the relationship between masseter muscle electromyography (EMG) burst/duration during wakefulness and TMD‐related symptoms, psychosocial status and pain‐related disability. Methods: Sixty participants were assessed masseter muscle activity during wakefulness using a data‐logger‐type ultraminiature EMG system and TMD‐related symptoms, psychosocial status and pain‐related disability through Axis I and II of the diagnostic criteria for TMD (DC/TMD). EMG bursts lasting longer than 0.25 s but less than 2.0 s and those lasting longer than 2.0 s were classified as phasic and tonic bursts, respectively. Results: Participants with palpation‐related pain in the temporalis and masseter muscles, as assessed through the DC/TMD examination form in Axis I, had more bursts (number/h) (p =.035 and p =.009, respectively) and longer duration (time/h) (p =.013 and p =.004, respectively) of tonic bursts of the masseter muscle during wakefulness. Participants with palpation‐related pain in the masseter muscles had higher oral behaviour scores during wakefulness using Axis II (p =.001), which affected the number and duration of tonic bursts of the masseter muscle activity during wakefulness (p =.011 and p =.007, respectively). Conclusion: As tonic bursts mainly reflect clenching, individuals with pain in the masseter muscles by palpation may have a high frequency and longer duration of clenching, as well as a high frequency of oral behaviours during wakefulness. [ABSTRACT FROM AUTHOR]

Background: The objective of this investigation is to assess the relationship between the utilisation of orthodontic intermaxillary elastics and temporomandibular disorder (TMD) symptoms in clear aligner patients and to examine the correlation between the elastic usage time with the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)—Axis II Evaluation Forms. Methods: This study was carried out on a total of 40 clear aligner patients using intermaxillary elastics in the experimental group and 30 clear aligner patients who did not use any intermaxillary elastics in the control group. The data were evaluated using the Mann–Whitney U, chi‐square, Fisher's exact chi‐square, and Fisher Freeman Halton exact chi‐square tests. Results: The characteristic pain intensity, mastication, mobility, communication, global and PHQ‐9 scores of the experimental group were significantly higher than those of the control group (p <.05). The characteristic pain intensity score, interference score and chronic pain grade score of patients using Class III elastics were statistically significantly higher than those of patients using Class II elastics (p <.05). Patients who used elastics for less than 6 months had statistically significantly higher PHQ‐9 scores than those who used elastics for more than 6 months (p <.05). Conclusions: Orthodontic treatment may affect occlusion, bite force and jaw movement, which may cause or worsen TMD symptoms, and the DC/TMD questionnaires can determine if orthodontic patients acquire TMD by assessing their psychosocial state and pain‐related problems. [ABSTRACT FROM AUTHOR]

Objectives: Intrapulpal calcifications can occur in the dental pulp of patients with diabetes. We focused on the association between ectopic calcifications in the dental pulp and advanced glycation end products (AGEs) in Spontaneously Diabetic Torii (SDT)‐fatty rats, an obese type 2 diabetic rat model, to determine the mechanism of calcification with pulp stone in the dental pulp. Materials and Methods: Pathologic calcification in the dental pulp of SDT‐fatty rats was observed using electron microscopy and immunohistochemical analysis. Moreover, mechanical analysis of periapical region of molar tooth against occlusal force was performed. Results: In SDT‐fatty rats, pathogenic pulpal calcifications occurred during blood glucose elevation after 6 weeks, and granular calcification was observed in the dental pulp after 11 weeks. Pentosidine, a major AGE, and the receptor for AGEs were strongly expressed in the dental pulp of SDT‐fatty rats. S100A8, TNF‐α, and IL‐6 also showed positive response in the dental pulp of the SDT‐fatty rat, which indicated pulpal inflammation. Blood flow disorder and hypoxic dental pulp cells were also observed. In silico simulation, strain from occlusal force concentrates on the root apex. Conclusions: Glycation makes blood vessels fragile, and occlusal forces damage the vessels mechanically. These are factors for intrapulpal calcification of diabetes. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Primary afferents originating from the mesencephalic trigeminal nucleus provide the main source of proprioceptive information guiding mastication, and thus represent an important component of this critical function. Unlike those of other primary afferents, their cell bodies lie within the central nervous system. It is believed that this unusual central location allows them to be regulated by synaptic input. In this study, we explored the ultrastructure of macaque mesencephalic trigeminal nucleus neurons to determine the presence and nature of this synaptic input in a primate. We first confirmed the location of macaque mesencephalic trigeminal neurons by retrograde labeling from the masticatory muscles. Since the labeled neurons were by far the largest cells located at the edge of the periaqueductal gray, we could undertake sampling for electron microscopy based on soma size. Ultrastructurally, mesencephalic trigeminal neurons had very large somata with euchromatic nuclei that sometimes displayed deeply indented nuclear membranes. Terminal profiles with varied vesicle characteristics and synaptic density thicknesses were found in contact with either their somatic plasma membranes or somatic spines. However, in contradistinction to other, much smaller, somata in the region, the plasma membranes of the mesencephalic trigeminal somata had only a few synaptic contacts. They did extend numerous somatic spines of various lengths into the neuropil, but most of these also lacked synaptic contact. The observed ultrastructural organization indicates that macaque trigeminal mesencephalic neurons do receive synaptic contacts, but despite their central location, they only avail themselves of very limited input. [ABSTRACT FROM AUTHOR]

This article discusses the rare occurrence of trigeminal neuralgia-like symptoms in patients with vestibular schwannomas (VS) compressing the trigeminal nerve (TN). The study aims to identify quantitative measurements that can evaluate potential TN tethering causing these symptoms. The researchers used various imaging modalities to assess the tethering of the VS onto the TN, including volumetric tumor measurements, curvature and angle measurements, signal intensity measurements, and T2-weighted MRI signals. The findings suggest that these quantitative measurements could be valuable in understanding the course of the disease and aiding treatment recommendations. [Extracted from the article]

This article explores the use of temporalis muscle thickness (TMT) and masseter muscle thickness (MMT) as measures of sarcopenia and proxies for frailty in patients with squamous cell carcinoma of the sinonasal tract (SNSCC) and sinonasal adenocarcinoma (SNAC). The study aimed to determine if lower TMT and MMT were associated with worse overall survival, 30-day readmission, and progression-free survival. However, the results showed that TMT and MMT measurements did not correlate with these outcomes in the study population. The authors suggest that further research with larger patient numbers and different types of pathology is needed to investigate the use of TMT and MMT as markers for frailty in sinonasal cancer. [Extracted from the article]

This article, published in the Journal of Neurological Surgery, explores the use of magnetic resonance imaging (MRI) and computed tomography (CT) to assess the thickness of the temporalis and masseter muscles as indicators of frailty in patients with sinonasal squamous cell carcinoma (SNSCC). The study found that both MRI and CT measurements correlated with frailty measures, but MRI measurements were better associated with frailty than CT measurements. The authors suggest that MRI should be considered the gold standard imaging for future studies on TMT and MMT in patients with SNSCC. [Extracted from the article]

Background: Various clinical studies performed in adults have shown the relationship between craniofacial morphology and masticatory muscle function. However, the growth of the masticatory muscle has not received such attention, when compared with the volume of studies on the skeletal growth of face. With this background and considering the widespread use of ultrasonography (USG), the following study was undertaken to provide some insights into the relationship between muscle and bone and facial morphology. Methods: This was a prospective, observational study conducted over a period of three years from 2012 to 2015 to assess the correlation between the thickness of the masseter muscle in Angle's normal occlusion and the various malocclusions of the dental arch as well as the facial form. Patients with a full complement set of teeth, normal tooth morphology, Angle's normal occlusion, Angle's class I-III malocclusion, those with a history of third molar extraction, and impaction were included in the study. Those with a history of any prior orthodontic treatment, restorations, or any missing teeth (except the third molar) were exempted from the study. The greater thickness of masseter muscle in relaxed and clenched state was recorded on USG. Facial morphology was determined with the aid of facial photographs. Results: The study was conducted on 140 patients. The class I normal occlusion group had the thickest masseter muscle, while the class III malocclusion group had the thinnest masseter muscle. Facial parameters showed highly significant gender-wise differences in class I normal occlusion, class I malocclusion, and class II division II malocclusion. There was a significant negative co-relation between the thickness of masseter muscle and facial forms in all the categories of Angle's classification as indicated by a negative regression coefficient B (P < 0.05). Conclusion: The masseter muscle thickness correlated directly with male gender and normal occlusion, and inversely with the degree of malocclusion and facial form. [ABSTRACT FROM AUTHOR]

During mastication, food undergoes state and texture changes influenced by various mechanical properties, including compression and fracturing of the molar teeth, mixing with saliva, and oral temperature. Prior studies have explored mastication simulators, however, no studies have assessed the forces and duration applied to the molars by the food during bolus formation. In this study, we developed a novel system that integrates a masticatory simulator and analysis method to evaluate mechanical properties. We developed ORAL‐MAPS which is equipped with 6‐axis force sensor, pneumatic pressure control mechanism, vertical movement, molar‐like module, artificial saliva injection unit, and temperature control apparatus. A gap exists between the upper and lower unit at the closest point, allowing the sensor to measure vertical upward force and duration from food, while compressed air provides constant downward pressure. We hypothesized a correlation between the total integrated muscle activity ratio obtained from the human masseter muscle electromyography (iEMG). We compared the normalized impulse obtained from ORAL‐MAPS with the normalized total iEMG obtained from human studies with four different types of gummy candies. As a result, the normalized total impulse of gummy candies A, B, C, and D were 1.00 ± 0.00, 1.29 ± 0.06, 0.95 ± 0.00, and 0.39 ± 0.0, respectively. The normalized total iEMG of the same gummy candies were 1.00 ± 0.00, 1.23 ± 0.15, 0.98 ± 0.09, and 0.45 ± 0.07, respectively. Thus, no significant difference was observed between the normalized total impulse obtained in vitro and the normalized total iEMG values for masticating the gummy candies B, C, and D (p >.05). [ABSTRACT FROM AUTHOR]

Determination of sarcopenia is crucial in identifying patients at high risk of adverse health outcomes. Recent studies reported a significant decline in masticatory muscle (MM) function in patients with sarcopenia. This study aimed to analyze the cross-sectional area (CSA) of MMs on computed tomography (CT) images and to explore their potential to predict sarcopenia. The study included 149 adult subjects retrospectively (59 males, 90 females, mean age 57.4 ± 14.8 years) who underwent head and neck CT examination for diagnostic purposes. Sarcopenia was diagnosed on CT by measuring CSA of neck muscles at the C3 vertebral level and estimating skeletal muscle index. CSA of MMs (temporal, masseter, medial pterygoid, and lateral pterygoid) were measured bilaterally on reference CT slices. Sarcopenia was diagnosed in 67 (45%) patients. Univariate logistic regression analysis demonstrated a significant association between CSA of all MMs and sarcopenia. In the multivariate logistic regression model, only masseter CSA, lateral pterygoid CSA, age, and gender were marked as predictors of sarcopenia. These parameters were combined in a regression equation, which showed excellent sensitivity and specificity in predicting sarcopenia. The masseter and lateral pterygoid CSA can be used to predict sarcopenia in healthy aging subjects with a high accuracy. [ABSTRACT FROM AUTHOR]

Background: Sarcopenia has been identified as a potential negative prognostic factor in cancer patients. In this study, our objective was to investigate the relationship between the assessment method for sarcopenia using the masseter muscle volume measured on computed tomography (CT) images and the life expectancy of patients with oral cancer. We also developed a learning model using deep learning to automatically extract the masseter muscle volume and investigated its association with the life expectancy of oral cancer patients. Methods: To develop the learning model for masseter muscle volume, we used manually extracted data from CT images of 277 patients. We established the association between manually extracted masseter muscle volume and the life expectancy of oral cancer patients. Additionally, we compared the correlation between the groups of manual and automatic extraction in the masseter muscle volume learning model. Results: Our findings revealed a significant association between manually extracted masseter muscle volume on CT images and the life expectancy of patients with oral cancer. Notably, the manual and automatic extraction groups in the masseter muscle volume learning model showed a high correlation. Furthermore, the masseter muscle volume automatically extracted using the developed learning model exhibited a strong association with life expectancy. Conclusions: The sarcopenia assessment method is useful for predicting the life expectancy of patients with oral cancer. In the future, it is crucial to validate and analyze various factors within the oral surgery field, extending beyond cancer patients. [ABSTRACT FROM AUTHOR]

Temporomandibular joint disorders (TMDs) are closely related to the masticatory muscles, but objective and quantitative methods to evaluate muscle are lacking. IDEAL-IQ, a type of chemical shift-encoded magnetic resonance imaging (CSE-MRI), can quantify the fat fraction (FF). The purpose of this study was to develop an MR IDEAL-IQ-based method for quantitative muscle diagnosis in TMD patients. A total of 65 patients who underwent 3 T MRI scans, including CSE-MRI sequences, were retrospectively included. MRI diagnoses and clinical data were reviewed. There were 19 patients in the normal group and 46 patients in the TMD group with unilateral disc displacement. The TMD group was subdivided into those with and without clenching. The right and left FF values of the masseter, medial, and lateral pterygoid muscles were measured twice by two oral radiologists on CSE-MRI, and the average value was used. FF measurements using CSE-MRI showed excellent intra- and inter-observer agreement (ICC > 0.889 for both). There were no statistically significant differences between the right and left FF values in the masseter, medial pterygoid, and lateral pterygoid of the normal group (p > 0.05). A statistically significant difference was found in the TMD group without clenching, in which the masseter muscle had a statistically significantly lower FF value on the disc displacement side (3.94 ± 1.61) than on the normal side (4.52 ± 2.24) (p < 0.05). CSE-MRI, which can reproducibly quantify muscle FF values, is expected to be a biomarker for objective muscle evaluation in TMD patients. The masseter muscle is expected to be particularly useful compared to other masticatory muscles, but further research is needed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Short- (SAI) and long-latency (LAI) afferent inhibition result from cortical integration of sensory inputs and motor output. • This work shows that SAI and LAI depend on type of sensory receptors, muscle function and cortical motor area. • This finding has pathophysiological implications in motor disorders involving specific muscular districts, such as focal dystonia. To compressively investigate sensorimotor integration in the cranial-cervical muscles in healthy adults. Short- (SAI) and long-latency afferent (LAI) inhibition were probed in the anterior digastric (AD), the depressor anguli oris (DAO) and upper trapezius (UT) muscles. A transcranial magnetic stimulation pulse over primary motor cortex was preceded by peripheral stimulation delivered to the trigeminal, facial and accessory nerves using interstimulus intervals of 15–25 ms and 100–200 ms for SAI and LAI respectively. In the AD, both SAI and LAI were detected following trigeminal nerve stimulation , but not following facial nerve stimulation. In the DAO, SAI was observed only following trigeminal nerve stimulation, while LAI depended only on facial nerve stimulation, only at an intensity suprathreshold for the compound motor action potential (cMAP). In the UT we could only detect LAI following accessory nerve stimulation at an intensity suprathreshold for a cMAP. The results suggest that integration of sensory inputs with motor output is profoundly influenced by the type of sensory afferent involved and by the functional role played by the target muscle. Data indicate the importance of taking into account the sensory receptors involved as well as the function of the target muscle when studying sensorimotor integration, both in physiological and neurological conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: In past populations, some individuals used their front teeth as tools for purposes other than eating, such as making tools or preparing food. These activities have an impact on both the visible part of the tooth (crown) through wear, as well as the part anchored deep in the gum (tooth root) by causing excessive production of a mineralized tissue called 'cementum'. Cementum surrounds the tooth root and forms throughout an individual's life. It records information about the individual's oral health, physiology, and chewing activities. Under certain conditions (e.g., significant mechanical stress or infection), cementum production becomes excessive and exceeds normal physiological limits, resulting in 'hypercementosis'. The present study aims to identify different patterns of cementum apposition and to propose probable causes. We examined a sample of 35 teeth (Sains-en-Gohelle, France, 7th–17th century) and identified four groups of cementum apposition: (i) impacted teeth that never erupted in the mouth, (ii) infected teeth, with caries or gum disease, (iii) hyperfunctional teeth subjected to high mechanical stress, and (iv) hypofunctional teeth that were not used in chewing due to the loss of opposing teeth. We conclude that hypercementosis could provide information on the life history of archeological specimens, even based on isolated teeth. The "teeth-as-tools" hypothesis posits that Neanderthals used their anterior teeth as a tool or a third hand for non-dietary purposes. These non- or para-masticatory activities (e.g., tool-making or food preparation prior to ingestion) have also been described in other past and extant human populations, and other Primates. Cementum is the mineralized tissue that covers the tooth root surface and anchors it to the alveolar bone. Under certain conditions (e.g., mechanical stress, infection), its production becomes excessive (i.e., beyond the physiological state) and is called 'hypercementosis'. Several studies in dental anthropology have established a correlation between the teeth-as-tools and hypercementosis. The present work aims to characterize the different patterns of cementum apposition on archeological teeth and discuss their supposed etiology. Using microtomography and confocal microscopy, the patterns of cementum apposition (i.e., thickness, location, and surface characteristics) were analyzed in 35 hypercementotic teeth (Sains-en-Gohelle, France; 7th–17th c. A.D.). Four groups were identified with distinct hypercementosis patterns: (1) impacted, (2) infected, (3) hypofunctional, and (4) hyperfunctional teeth. Characterizing hypercementosis can contribute to documenting the oral health status (paleopathology) and/or masticatory activity of individuals, even from isolated teeth. This has implications for the study of fossil hominins, particularly Neanderthals, known for their use of anterior teeth as tools and frequent and substantial occurrence of hypercementosis. [ABSTRACT FROM AUTHOR]

Temporomandibular dysfunction (TMD) encompasses several conditions affecting the temporomandibular joint and jaw muscles, leading to orofacial pain and other symptoms. Botulinum toxin is a potential therapy for relieving pain, improving jaw function, and reducing the use of analgesics. This study aims to systematically illustrate the application of botulinum toxin in the therapeutic context of TMD. This study took the form of a literature review, in which an analysis of knowledge repositories was conducted, including Medline (U.S. National Library of Medicine), accessed via PubMed, as well as Lilacs (Latin American and Caribbean Literature in Health Sciences), Scielo (Scientific Electronic Library Online), and Google Scholar. The selection involved the inclusion of studies published from 2015 to 2023. The literature review identified botulinum toxin as an effective and safe therapeutic alternative for TMD patients. The manifestation of side effects, when reported, was predominantly mild and transient in nature, granting botulinum toxin the prospect of establishing itself as a promising therapeutic option in refractory cases to conventional approaches. However, it is important to emphasize the need for further studies and clinical trials to further consolidate the efficacy and safety associated with the use of botulinum toxin as a treatment for TMD. [ABSTRACT FROM AUTHOR]

Objective: Temporomandibular disorders (TMD) comprise a cluster of conditions with a wide range of etiological factors that causes pain and discomfort in the masticatory muscles (TMD-M) and temporomandibular joints (TMD-J). More than 50% of the patients with TMD report regular usage of drugs. However, there is still no consensus, nor is there any evidence-based support for clinicians when choosing between different drugs. Therefore, this systematic review, including a network meta-analysis (NMA), aimed to evaluate the scientific evidence and discuss the pharmacological treatment options available to treat painful TMD. Method: An electronic search was undertaken to identify randomized controlled trials (RCTs) investigating pharmacological treatments for TMD-M and/or TMD-J, published until 6 April 2023. Since only 11 articles could be used for an NMA regarding TMD-M, a narrative synthesis was also performed for all 40 included RCTs. The quality of evidence was rated according to Cochrane's tool for assessing risk of bias, while the certainty of evidence was rated according to Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: When it comes to TMD-M, evidence arises for wet needling therapies with BTX-A, granisetron, and PRP as well as muscle relaxants. For TMD-J, evidence points toward pharmacological treatment approaches including non-steroidal antiinflammatory drugs (NSAIDs) and glucocorticosteriods (for inflammatory conditions) as well as hyaluronic acid and dextrose. Conclusions: The evidence clearly indicates that the pharmacological treatment approaches differ between TMD-M and TMD-J. Therefore, it is of great importance to first try to uncover each patient's individual and multifactorial etiology and then employ a multifaceted treatment strategy, including pharmacological treatment approaches. [ABSTRACT FROM AUTHOR]