Search Results (122)

Background: Temporomandibular disorders are a generic term referred to clinical conditions involving the jaw muscles and temporomandibular joint with multifactorial pattern and genetic background. The aim of this observational study was to investigate the correlation between craniomandibular disorders and the presence of occlusal alterations. A clinical evaluation of the occlusal and articular status of the patients was carried out, integrating the latter with the electromyographic recording the activity of the masseter and temporalis muscles. Methods: A clinical observational study on 20 adults assessed temporomandibular disorders using DC/TMD criteria, anamnesis, clinical exams, occlusal and electromyographic analyses. Occlusion was evaluated morphologically and functionally. Electromyography tested static/dynamic muscle activity. Data were statistically analyzed using t-tests and Pearson correlation (p < 0.05). Results: Electromyographic analysis revealed significant differences between subjects with and without visual correction, suggesting that visual input influences masticatory muscle activity. Correlations emerged between occlusal asymmetries and neuromuscular parameters. These findings highlight clinical implications for mandibular function, muscle symmetry, and the potential for therapeutic rebalancing through targeted interventions. Conclusions: The study demonstrates a significant correlation between visual–motor integration and masticatory muscle efficiency. It emphasizes lateralized neuromuscular activation’s influence on occlusal contact distribution. Moreover, it identifies mandibular torsion–endfeel inverse correlation as a potential diagnostic marker for craniomandibular dysfunctions via surface electromyography. Full article

The study of muscle activity as a function of vertical dimension has been extensively developed in the field of oral physiology. It involves asking subjects to open their mouths to a predetermined distance and then recording muscle activity in that position. Most studies perform this without accounting for physiological differences among patients. The objective of this study is to present a protocol for recording muscle activity at various mouth-opening levels using electromagnetic articulography (EMA) and surface electromyography (sEMG), normalizing opening degrees and muscle activity. Muscle activity recordings were obtained in the position of maximum intercuspation and maximum mouth opening. Based on these recordings, the position corresponding to 5–50% of maximum opening was calculated. EMA and sEMG recordings were performed at these levels. Muscle activity during maximum voluntary clenching was recorded and used to normalize the previous data. In all cases, three 5-second recordings were obtained. The analysis of muscle activity using EMA and sEMG did not present any complications. A slight difference was observed between the intended percentage of mouth opening and the actual percentage achieved. The method described in this study is a tool that allows for the analysis of muscle activity at various mouth-opening levels in a way that has not been previously explored in the literature. Full article

Background: Surface electromyography (sEMG) enables the non-invasive assessment of muscle activity and is widely used in orthodontics for evaluating masticatory muscles. However, little is known about the dynamic changes in facial expression muscles during orthodontic treatment. This study aimed to investigate alterations in facial muscle tone during the leveling and alignment phase in adult female patients undergoing fixed appliance therapy. Methods: The study included 30 female patients aged 20–31 years who underwent sEMG assessment at four time points: before treatment initiation (T0), at the start of appliance placement (T1), three months into treatment (T2), and six months into treatment (T3). Muscle activity was recorded during four standardized facial expressions: eye closure, nasal strain, broad smile, and lip protrusion. Electrodes were placed on the orbicularis oris, orbicularis oculi, zygomaticus major, and levator labii superioris alaeque nasi muscles. A total of 1440 measurements were analyzed using Friedman and Conover-Inman tests (α = 0.05). Results: Significant changes in muscle tone were observed during treatment. During lip protrusion, the orbicularis oris and zygomaticus major showed significant increases in peak and minimum activity (p < 0.01). Eye closure was associated with altered orbicularis oris activation bilaterally at T3 (p < 0.01). Nasal strain induced significant changes in zygomaticus and levator labii muscle tone, particularly on the right side (p < 0.05). No significant changes were noted during broad smiling. Conclusions: Orthodontic leveling and alignment influence the activity of selected facial expression muscles, demonstrating a dynamic neuromuscular adaptation during treatment. These findings highlight the importance of considering soft tissue responses in orthodontic biomechanics and suggest potential implications for facial esthetics and muscle function monitoring. Full article

Background/Objectives: Bruxism has been associated with dysregulation of the autonomic nervous system (ANS). Visceral manual therapy (VMT) has shown beneficial effects on the vagal tone and modulation of ANS activity. This study aimed to evaluate the immediate and short-term effects of VMT in individuals with clinically based bruxism. Methods: A single-blind randomized controlled trial was conducted including 24 individuals with clinically based bruxism. Participants received two sessions of either VMT or a sham placebo technique. Outcome measures included heart rate variability (HRV), both normal-to-normal intervals (HRV-SDNN), and the root mean square of successive normal-to-normal intervals (HRV-RMSSD), as well as muscle tone and stiffness and pressure pain thresholds (PPTs). Measurements were made at T1 (baseline), T2 (post-first intervention), T3 (pre-second intervention), T4 (post-second intervention), and T5 (4-week follow-up). Results: A significant time*group interaction was observed for HRV-SDNN (p = 0.04, η² = 0.12). No significant changes were found for muscle tone or stiffness. PPTs significantly increased at C4 after the second session (p = 0.049, η² = 0.16) and at the left temporalis muscle after the first session (p = 0.01, η² = 0.07). Conclusions: The findings suggest that two sessions of VMT may lead to significant improvements in HRV-SDNN compared to the placebo, suggesting a modulatory effect on autonomic function. No consistent changes were observed for the viscoelastic properties of the masticatory muscles. Isolated improvements in pressure pain sensitivity were found at C4 and the left temporalis muscle. Further research with larger sample sizes and long-term follow-up is needed to determine the clinical relevance of VMT in the management of signs and symptoms in individuals with bruxism. Full article

Background: The occlusal angle (OA), influenced by pillow height, may affect muscle tension in the head and neck. However, its optimal range for minimizing muscle activation has not been clearly defined. Objective: This study aimed to investigate the effects of OA on the resting muscle activity of masticatory and cervical muscles and to identify an optimal OA range using cluster analysis and linear mixed-effects modeling. Methods: The resting muscle activities of the masseter (MAS), temporalis (TEM), sternocleidomastoid (SCM), and posterior vertebral muscles (PVM) were measured at OA conditions modulated by pillow heights of 0, 5, and 10 cm at 0, 1, and 5 min in the supine position. Intraclass correlation coefficients (ICCs) assessed measurement reliability. Statistical analyses included ANOVA, ROC curve analysis, k-means clustering, and linear mixed-effects models. Results: MAS and TEM resting muscle activity ratio (RMR) significantly increased with larger OA values (p < 0.001), while SCM showed decreased activation (p = 0.001). An OA range of 105°–111° was identified as the center of a low-activity cluster, and an upper cut-off of 138° was associated with potential muscular overload. ICC values for MAS and SCM ranged from 0.82 to 0.89, indicating excellent test–retest reliability. Conclusions: OA modulated by pillow height is a modifiable factor that influences muscle activity. An OA of 105°–111° may serve as a practical comfort zone, especially for individuals at risk of TMDs. Full article

Awake Bruxism (AB) is defined as masticatory muscle activity during wakefulness, characterized by repetitive or sustained tooth contact and/or the bracing or thrusting of the mandible. AB remains less understood than Sleep Bruxism (SB), and its identification remains a methodological challenge. The aim of this study was to introduce the Awake Bruxism Identification Tool (ABIT), developed for children and adolescents aged 8 to 12 years, to facilitate the identification of AB. The tool integrates data from self-reports, clinical examinations, and the Ecological Momentary Assessment (EMA). It comprises questionnaires using a five-point Likert scale, an analog EMA component involving color-based responses, and a clinical inspection. The tool adopts the concept of an “AB Spectrum”, as it generates individualized scores based on the combined outcomes of these multiple assessment components. The ABIT was piloted with ten families to evaluate its comprehensibility, applicability, and reliability. The results demonstrated that the participants found the questions understandable, that the tool had a minimal impact on daily family routines, and that it required approximately 5–10 min to complete. Additionally, the test–retest reliability indicated temporal stability. In terms of identification, four children were classified within the “AB identified by report and self-report,” while three were identified through the “report, self-report, and EMA.” Based on participant feedback, adjustments were made to the instrument, including the addition of an item addressing Sleep Bruxism. Although the ABIT is being applied for the first time in a research setting, it presents a promising, clinically relevant approach grounded in the self-perception of children and their caregivers. Full article

Background: Temporomandibular disorders (TMDs) represent an umbrella term encompassing various musculoskeletal dysfunctions, including those affecting the masticatory muscles. This study aimed to compare the salivary levels of non-enzymatic antioxidants and redox balance between patients with temporomandibular myofascial pain with referral and matched healthy controls. Methods: The sample consisted of 44 individuals diagnosed with temporomandibular myofascial pain with referral and a matched control group. The procedure included a clinical examination based on the Diagnostic Criteria for Temporomandibular Disorders and saliva collection. Biochemical analysis included the assessment of reduced glutathione (GSH) levels, total antioxidant status (TAC), total oxidant status (TOS), and the oxidative stress index (OSI). Results: Patients with temporomandibular myofascial pain with referral exhibited higher levels of total oxidant status and glutathione. The mean value of total antioxidant capacity was lower, although the median was higher compared to the control group. No statistically significant differences were observed in the oxidative stress index between the two groups. Conclusions: Patients with temporomandibular myofascial pain with referral exhibit oxidative imbalance, reflected by increased salivary levels of non-enzymatic antioxidants, elevated total oxidant status, and significant differences in antioxidant capacity compared to healthy controls. Individually tailored physical activity, proper nutrition, and targeted supplementation may be necessary to maintain oxidative-antioxidant balance in this patient population. Full article

Stomatognathic dysfunctions, particularly bruxism, orofacial pain, and temporomandibular joint (TMJ) disorders, are frequently associated with anxiety and depression. However, the reverse hypothesis that these dysfunctions may act as peripheral stressors contributing to neuropsychological imbalance by activating the hypothalamic–pituitary–adrenal (HPA) axis remains underexplored. Objective: To assess the relationship between the severity of stomatognathic symptoms and both physiological and psychological stress markers to determine whether such dysfunctions may influence or exacerbate anxiety and depressive disorders. Methods: A cross-sectional observational study was conducted on 120 adult patients. Clinical assessment was included evaluation of TMJ function, bruxism, and orofacial pain. Psychological screening was performed using validated questionnaires (GAD-7 for anxiety and PHQ-9 for depression). Electromyographic (EMG) analysis of the masseter and temporalis muscles was conducted, along with the quantification of salivary cortisol using an enzyme-linked immunosorbent assay (ELISA). Multiple regression models were applied to identify statistically significant correlations (p < 0.05). Results: A positive correlation was found between the severity of stomatognathic dysfunction and scores on anxiety and depression measures, along with elevated salivary cortisol levels and increased masticatory muscle activity. Conclusions: These findings suggest a bidirectional relationship between stomatognathic dysfunctions and neuropsychological status, underscoring the potential value of integrated therapeutic approaches that combine dental care with psychological support. Full article

(1) Background: The present study was designed to analyze the relationship between masticatory muscle activity, oxygen body saturation, and heart rate in patients with temporomandibular disorders (TMDs). (2) Methods: A total of 104 individuals with a painful form of TMDs were included in the study, consisting of 72 women and 32 men, with an average age of 24 ± 3 years. The control group included 77 individuals, comprising 44 women and 33 men, with an average age of 24 ± 3 years. An electromyographic study was conducted at rest, focusing on the temporalis (TA) and masseter muscles, alongside an oxygen saturation and heart rate analysis using a pulse oximeter. (3) Results: Analysis of the correlations between oxygen saturation and the studied muscles revealed a positive correlation between the resting activity of the TA and oxygen saturation, with a small effect size in the TMDs group. This positive correlation suggests increased muscle oxygenation is associated with higher resting activity in TMDs patients. (4) Conclusions: This study indicates that oxygen body saturation is associated with increased resting activity in the temporalis muscles of individuals with TMDs. Increased muscle tension in TMDs patients may impact the metabolism of the temporalis muscle, leading to higher energy and oxygen demands. This could be linked to hypermetabolism and an increased energy burden in these muscles at rest. Full article

Background: Temporomandibular disorder (TMD) is a collective term covering acute or chronic musculoskeletal and neuromuscular pain associated with the masticatory muscles, temporomandibular joint, and the associated structures. The surface electromyography (sEMG) test represents clinical potential as an additional diagnostic tool. The purpose of this study was to evaluate differences in masseter and temporalis muscle activity (in sEMG) in subjects with TMD compared to a control group. Methods: The TMD group included 45 people qualified according to the diagnostic criteria for temporomandibular disorder (DC/TMD). In the control group, there were 30 subjects. All participants underwent detailed examinations including sEMG diagnosis of the masseter and temporalis muscles. The sEMG was measured both at rest and during maximal voluntary contraction (MVC). Amplitude root mean square (A_RMS) values for the analysis were determined. Results: No differences were shown in the value of the results between TMD and control group in RS A_RMS transformed data values (p = 0.086) and in the MVC A_RMS transformed data values (p = 0.536). The presence of TMD has no significant effect on the symmetry index value for the temporalis (p = 0.42) and masseter muscles (p = 0.379). Conclusions: Analysis of both raw and normalized sEMG signals is insufficient to differentiate TMD patients from healthy individuals. Full article

Background/Objectives: The study aimed to validate the diagnostic system proposed by the Standardized Tool for the Assessment of Bruxism (STAB) by correlating the results obtained based on questionnaire and non-instrumental and instrumental tools. Methods: The study had three stages (questionnaire, clinical examination, and electromyographic study). The subjects completed a questionnaire and clinical exam. Positive signs of bruxism included oral mucosal signs and the presence of dental wear according to the BEWE index. In stage three, sEMG was performed after allocating subjects into four groups according to the questionnaire and clinical exam results: sleep bruxism (SB), awake bruxism (AB), sleep and awake bruxism (SB AB), and no bruxism (no B). After the third stage, a new selection was made, and the subjects were divided into four groups, according to sEMG results. Diagnostic accuracy was computed for possible bruxism SB and grinding and clenching sound diagnosis, possible bruxism AB and AB acknowledgment, possible bruxism SB AB, and tooth wear index. Results: For SB, the sensitivity and specificity of the tools were the highest. The non-instrumental questionnaire and clinical assessment identified 67% of SB cases and 89% without SB. For AB, the specificity was higher (84%), while the sensitivity was lower (55%), as almost half of the subjects were not aware of the presence of AB. The tests showed a low sensitivity (15%) but a high specificity (83%) for tooth wear. The absence of tooth wear was frequently associated with the absence of bruxism, while the presence of tooth wear did not necessarily imply the existence of bruxism. Conclusions: Non-instrumental evaluation of bruxism through questionnaires and clinical exams is valuable, especially for SB. Instrumental evaluation through electromyography remains a gold standard for bruxism diagnosis. Full article

Hardness is one of the dominant sensory characteristics of food. This study estimated the effect of sensitivity to hardness on the texture perception and chewing function using 2, 4, and 6% agar gels. Increasing the concentration of agar resulted in an increase in gel hardness and springiness, measured by texture profile analysis. Non-trained participants (n = 95) reported more subjective hardness and springiness during chewing gel samples as the agar concentration increased. Based on the relationship value of the instrumental and sensory data, all participants were divided into low-, medium-, and high-sensitivity groups (n = 25, 44, and 26). Low sensitivity to hardness was associated with low sensitivity to brittleness, springiness, chewiness, moisture, and swallowability. In all three groups, enhanced agar gel hardness increased the temporal chewing characteristics in a similar manner. However, in those with a high hardness sensitivity, the area amplitude of the masseter and temporalis muscles grew to a lesser extent than in those with a low or medium sensitivity. The activity of the suprahyoid muscles increased with the increasing agar gel hardness, regardless of sensitivity. All groups showed a similar salivation and bolus fragmentation while chewing gel. Thus, people’s sensitivity to hardness was associated with different perceptions of the gel’s textural properties and changes in masticatory muscle activity. Full article

Background: Temporomandibular disorders (TMDs) represent a significant public health issue, among which masticatory muscle pain is the most common. Current publications increasingly indicate surface electromyography (sEMG) as an effective diagnostic tool for muscle dysfunctions that may be employed in TMDs recognition. The objective of this study was to establish reference ranges for TMDs patients with masticatory muscle pain and healthy individuals in the electromyographic Functional Clenching Index (FCI) for the temporalis muscles (TAs) and masseter muscles (MMs). This research aimed to provide an additional diagnostic tool for TMDs patients. Methods: A total of 48 individuals (n = 30 women and n = 18 men) with the muscular painful form of TMDs were recruited alongside a numerically and gender-matched control group—healthy, pain-free controls. The Functional Clenching Indexwas calculated for both groups. Results: Data analysis revealed statistically significant differences with a very large effect size. Healthy individuals had higher FCI scores compared to those with TMDs. The healthy group exhibited higher threshold values compared to the TMDs group. Conclusions: For healthy individuals, the FCI ranges for TAs were between 58 and 145, while for MMs, between 72 and 210. Lower values may indicate muscle activation disorders and occur in patients with the painful, muscular form of TMDs. This is the first study to define reference ranges for electromyographic indices; therefore, caution is recommended, and the replication of this study on a larger and more culturally diverse sample is advised. Full article

Temporomandibular disorders (TMDs) encompass various clinical conditions associated with the temporomandibular joint (TMJ) and the masticatory muscles. TMD symptoms include pain in the orofacial region, restricted or altered mandibular movement, and sounds associated with the temporomandibular joint (TMJ). This condition adversely affects quality of life, social functioning, and daily activities, and may also contribute to widespread pain syndromes and comorbidities, including irritable bowel syndrome (IBS). IBS is a common chronic functional disorder of the lower gastrointestinal tract, characterized by recurrent abdominal pain associated with impaired bowel symptoms. Previous studies indicate an association between TMD and IBS. This scoping review examined the correlation between TMD and IBS concerning their pathology, frequency, and severity, and the potential similarities in how the nervous and endocrine systems influence them. PubMed, SCOPUS, Web of Science, and Google Scholar search engines were utilized to identify suitable studies for this article. Following the application of selection criteria, a total of 58 clinical papers met the eligibility requirements for inclusion in the systematic review. Research showed that both conditions significantly enhance the development of one another and have mutual comorbidities. Both ailments were proven to modify central nervous system processing, leading to high comorbidity in patients. Combining dental and gastroenterological treatments, including a simultaneous therapeutic approach, can significantly enhance patients’ quality of life, but further research is needed for a holistic approach. Full article

Background and Objectives: Sport climbing’s popularity has grown with its inclusion in the Olympics and increased accessibility. Understanding the relationship between hand dominance, grip strength, endurance, and the involvement of masticatory and neck muscles can provide valuable insights into the neuromuscular adaptations specific to sport climbing, potentially aiding performance optimization and injury prevention in intermediate and advanced climbers. This study analyzes if the dominant hand has greater isometric endurance and isometric manual grip strength parameters than the non-dominant one and examines its relation to the masticatory and neck muscles in intermediate and advanced sport climbers. Materials and Methods: The study was conducted on 41 participants who were divided into two groups according to the IRCRA classification. A level 2 (Lv2) group consisting of 18 climbers and a level 3 (Lv3) group consisting of 23 climbers were identified. First, isometric manual grip strength and isometric endurance were measured using a dynamometer following the protocol of the first three and the last three repetitions (PC3) and the first six and the last six repetitions (PC6). Next, masticatory and neck muscle activity was assessed using surface electromyography, following the same protocol. Results: Greater activity of the temporalis muscle was observed on the non-dominant side in the advanced climber’s group (p = 0.045). The decrease in bioelectric activity was lower on the dominant side in group Lv3 compared to Lv2. In intermediate climbers, the bioelectrical activity of the masseter muscles in PC3 was greater on the non-dominant side, and in PC6, was greater on the dominant side. The digastric muscles showed a greater decrease in isometric endurance on the non-dominant side. Conclusions: Advanced climbers demonstrated greater isometric endurance and isometric manual grip strength parameters in both dominant and non-dominant hands compared to intermediate climbers. The masticatory muscles exhibited higher electromyographic activity on the non-dominant side in the masseter muscles and higher electromyographic activity on the dominant side in the temporalis muscles and digastric muscles. Full article