Temporomandibular Disorders Group Research Articles

Is malocclusion a predictor of pain in patients suffering from TMD pain?

Temporomandibular disorders (TMD) affect the masticatory muscles, temporomandibular joints (TMJs) and associated structures. The relationship between occlusion and TMD is a contentious issue in the dental field. Although there is a strong argument against invasive and irreversible therapeutic TMD procedures, the TMD biopsychosocial model is still not accepted by some clinicians. Hence, this study aimed to verify whether malocclusions are related to TMD pain. The study included 49 adult patients with one or multiple TMD diagnoses and without any other diseases that could mimic TMD. A reliable investigator diagnosed the patients using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) protocol. The sample was divided into pain and non-pain TMD groups, and the predictor of malocclusion was categorized as the dependent variable. There were 33 patients in the TMD pain group and 16 patients in the non-pain TMD group. Analyses were conducted at a significance level of 0.05. The χ2 test (with Yates' correction for 2 × 2 matrix) was used to compare qualitative variables between the groups. Malocclusion was present in 13 patients in the pain group and 7 patients in the non-pain group. According to our study, there is no correlation between malocclusion and TMD pain.

Quantitative and qualitative condylar changes following stabilization splint therapy in patients with temporomandibular joint disorders with and without skeletal lateral mandibular asymmetry: a cone beam computed tomographic study

BackgroundTemporomandibular disorders (TMDs) encompass pain and dysfunction in the jaw, muscles, and adjacent structures. This study aimed to explore the quantitative (condylar position, morphology) and qualitative (bone mineral density (BMD)) therapeutic outcomes following a stabilization splint (S.S.) therapy in adult patients diagnosed with TMD (Arthralgia) with/without lateral mandibular asymmetry (MA) using cone beam computed tomography (CBCT).MethodsIn this retrospective clinical study, 60 adult TMD patients who received S.S. therapy were enrolled and allocated into the TMD group (TMDG) and TMD with MA group (TMD + MAG). The diagnosis was made according to the Diagnostic Criteria for TMD (DC/TMD) AXIS I. MA was measured from the mid-sagittal plane to the Menton point. CBCT was used to scan the temporomandibular joints pre- (T0) and post- (T1)-treatment for three-dimensional analysis. Intra- and intergroup statistical comparisons were performed using the Wilcoxon signed ranks and the Kruskal‒Wallis test.ResultsFor quantitative comparisons, there was a statistically significant difference between T0 and T1 in the joint spaces of TMD + MAG (anterior, superior, posterior, and coronal lateral on the deviated side as well as in the superior, coronal medial joint space of the contralateral side). Morphologically, the deviated side had a narrower condylar width, reduced condylar height, and a steeper eminence angle. In contrast, the contralateral side tended to have a greater condylar length. For qualitative measurements, BMD also showed statistical significance between T0 and T1 in the majority of the condyle slopes (AS, SS, PS, and LS on the deviated side and in AS and MS on the contralateral side) of TMD + MAG. Additionally, only the AS and PS showed significance in TMDG.ConclusionMultiple joint space widening (AJS and CMS) and narrowing (SJS, PJS, and CLS) could characterize the deviated side in TMD + MA. Factors like narrower condylar width, reduced condylar height, and steeper eminence angle on the deviated side can worsen TMD + MA. Proper alignment of the condyle-disc position is essential for optimal function and load distribution, potentially affecting bone mineral density (BMD). MA plays a prominent role in disturbing bone densities. S.S. therapy shows more evident outcomes in TMD + MAG (on the deviated side compared to the contralateral side) than the TMDG.

Depression and the risk of developing temporomandibular disorders in different diagnostic groups: A systematic review with meta-analysis

ABSTRACT Objective: To evaluate the role of depression in the development of TMD groups. Methods: This systematic review with meta-analysis compared the prevalence and scores of depression between TMD groups and controls. Results: The results showed that depression was a significant risk factor in the development of RDC/TMD axis I muscle disorders (group I) and arthralgia/osteoarthritis/osteoarthrosis (group III), and non-significant for disc displacements (group II). Severe depression had almost four times the risk of developing TMD as compared to moderate depression. Conclusion: These findings suggest that addressing psychological factors in general, and depression in particular, in the managemenof TMD is crucial, especially in those TMD groups with higher pain levels (I and III), and the TMD pain reduction is crucial in reducing depression levels.

Biomechanical study of temporomandibular joints of patients with temporomandibular disorders under incisal clenching: A finite element analysis

Temporomandibular disorders (TMD) encompass a collection of pathologies. Within the multitude of etiological factors contributing to TMD, mechanical factors hold significant importance. The aim of this investigation was to assess the magnitude and distribution of stresses encountered by the temporomandibular joints (TMJs) during incisal clenching among TMD patients while also elucidating the mechanical pathogenesis underlying TMD. Ten asymptomatic subjects and ten TMD patients were recruited. The Control, Bilateral, and Unilateral groups were set. The contact stress, maximum principal stress, and minimum principal stresses of TMJ structures among the groups were compared. In addition, comparisons of the contact stress distribution among the groups were adopted. In the Control and Bilateral groups, the magnitudes of stresses (contact stress, maximum and minimum principal stresses) between the right and left sides showed no significant difference (P > 0.05). For unilateral TMD patients,the minimum principal stress on the condyle in the Uni-N group (the normal side) was significantly greater than thatin the Uni-T group (the TMD side)(P = 0.016, mean difference 9.99 MPa [95 %CI: 3.11 to 16.87]). Furthermore, stresses on the condyle and fossa of the patients were significantly greater than those of asymptomatic subjects (P < 0.05). The contact stress distributions were concentrated in the Control group while irregular in the TMD groups. In conclusion, asymmetrical contact stress distributions were observed in unilateral TMD, with excessive stresses on the healthy side. The protection of the healthy TMJ during treatment is recommended for patients with unilateral TMD.

Disclosure orthodontic and TMD-new study.

Cooperative analysis of participants and controls. Wiley Online Library, National Institute of Health, ResearchGate, ScienceDirect, Google Scholar. Human clinical trials age 18-30 years old, a case-control study included 291 individuals, 192 TMDs and 99 controls. All patients underwent assessment based on a questionnaire and a clinical examination according to Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Patients who underwent orthodontic treatment were compared to those who did not, regarding their trauma history, bruxism, aggressive teeth brushing, level of oral hygiene, pain scores, muscle tenderness scores and subjective sleep quality. Medical and/or dental emergencies, subjects with a history of drug, alcohol or medication abuse, fibromyalgia, being pregnant or lactating, having a coexisting mental, psychiatric, or physical disability, cancerous or significant medical problems and the consumption of drugs and/or medications that affect the nervous system including narcotics, TCA (tricyclic antidepressants), anticonvulsant, muscle relaxants and medication overuse headache. To identify differences between groups, categorical independent variables were analysed using the chi-square test or likelihood ratio, while numeric independent variables were analysed using independent t-tests and analysis of variance (ANOVA). A two-tailed level of statistical significance (α) was established at 0.05. Analysis of multicollinearity was performed following the univariate analyses to examine the collinearity among the independent variables and select independent variables with minimal correlation. Among the highly correlated variables, only one was selected for inclusion in the multivariate model, with the specific variable chosen based on contextual considerations. The research comprised a total of 291 individuals, consisting of two distinct groups: the TMD group (192 participants, 66%) and the control group (99 participants, 34%). Within the TMD group, further subcategorization was conducted, including MMP (masticatory muscle pain) with 44 individuals (15%); TMJD with 26 individuals (9%); and TMP (both MMP and TMJ) with 122 individuals (42%). Using a "holistic" and a "collinearity statistical approach and the utilization of a multivariate model" the conclusion is that TMD is not associated with orthodontics.

Use of Surface Electromyography to Evaluate Effects of Therapeutic Methods on Masticatory Muscle Activity in Patients with Temporomandibular Disorders: A Narrative Review

The presented narrative review aims to present the impact of therapeutic methods on the masticatory muscle activity measured using surface electromyography (sEMG) in patients with temporomandibular disorders (TMDs). Original interventional studies with baseline data for diagnosed TMD groups with full-text articles in English published in scientific journals in the last ten years were included in the evaluation process. The following narrative review considered only clinical, controlled, and randomized studies. Articles that included the following parameters were qualified for this review: adult participants, diagnosis of temporomandibular disorder, the presence of a musculoskeletal dysfunction, no other severe comorbidities, use of therapeutic interventions, and sEMG measurement before and after the intervention. Ten papers were accepted and analyzed for the final evaluation in the presented review. Several studies using surface electromyographic examination prove the effectiveness of various therapies to normalize the bioelectrical activity of the masticatory muscles, either reduction during rest or increase during a functional task in patients diagnosed with temporomandibular disorders. This narrative review shows the influence of manual and physical treatments on electromyographic masticatory muscle activity, including soft tissue mobilization, transcutaneous electrical nerve stimulation, low-level laser therapy, and moist heat therapy. Changes in masticatory muscle activity coincided with changes in TMD-associated pain and range of mandibular mobility.

Cross-Cultural Validation of the Thai Oral Health Impact Profile for Temporomandibular Disorders

ObjectivesThe Oral Health Impact Profile for Temporomandibular Disorders (OHIP-TMDs) is a validated condition-specific outcome measure to help guide decision-making in the management of the condition. There is no Thai version of OHIP-TMDs, and therefore the original English version needs cross-cultural adaptation translation, and validation with a Thai population to reduce the anomalies due to language and cultural differences. This study aimed to develop the Thai-language version of OHIP-TMDs, perform a cross-cultural adaptation to Thailand, and assess its content validity, internal consistency, reliability, and construct validity. MethodsThe original English version of OHIP-TMDs was forward and backward translated into Thai language using the International Network for Orofacial Pain and Related Disorders methodology (INfORM) protocol for cross-cultural adaptation. The Content Validity Index (CVI) was performed by 5 orofacial pain (OFP) specialists to establish content validity. The OHIP-TMDs-T was then tested in 2 groups of Thai dental patients including 110 TMD patients and 110 control participants. The internal reliability and test-retest reliability (n = 30) were investigated in the TMD group using Cronbach alpha coefficient and intraclass correlation coefficient (2-way mixed effect model), respectively. The difference in OHIP-TMDs-T score between the TMD group and control group was investigated for known group validity. ResultsCronbach alpha and intraclass correlation coefficients were 0.942 and 0.797, respectively. The CVI collected from the OFP specialists was 0.92. There was a statistical difference in the OHIP-TMDs-T overall score between the TMD group (95% CI, 40–46) and control group (95% CI, 2.0–3.4) (Z = 9.060, r = 1, P < .001). ConclusionsThe OHIP-TMDs-T is a valid and reliable tool for evaluating the quality of life and the impact on oral health in Thai patients with TMD.

The Relationship between Kinesiophobia, Emotional State, Functional State and Chronic Pain in Subjects with/without Temporomandibular Disorders

Although there is growing evidence that kinesiophobia is correlated with temporomandibular disorders (TMD), its relationship with other characteristic TMD comorbidities, such as depression, anxiety, functional limitations, and pain in the TMD population, has rarely been investigated. This study aims to evaluate the relationship between kinesiophobia, emotional state, functional state and chronic pain in subjects both with and without TMD. A total of 94 subjects participated in the study and were divided into two groups (47 subjects each)—TMD (subjects with temporomandibular disorders) and nTMD (asymptomatic controls)—on the basis of the RDC/TMD protocol. All measurements were taken with self-administered questionnaires: TSK-TMD for kinesiophobia, PHQ-9 and GAD-7 for psychoemotional state, JFLS-20 for jaw functional limitations, and GCPS for chronic pain. The prevalence of kinesiophobia in the TMD group was 38.3% for moderate risk, and 61.7% for high risk. The TMD group showed significantly higher scores in all categories (kinesiophobia, depression, jaw functional limitations and chronic pain), with the exception of anxiety which was right at the cut-off point. Moreover, a significant correlation was found between kinesiophobia (TSK-TMD) and jaw functional limitations (JFLS-20). Results of this study could provide new insight into the relationship between kinesiophobia and TMD, further improving the diagnosis process.

Females with painful temporomandibular disorders present higher intracortical facilitation relative to pain-free controls.

This study aimed to investigate cortical excitability differences in the primary motor cortex (M1) hand representation between individuals with temporomandibular disorders (TMD) and healthy controls. We assessed resting motor thresholds, motor-evoked potentials (MEPs), intracortical inhibition, and intracortical facilitation and explored potential associations with clinical and psychosocial characteristics in the TMD group. We recruited 36 female participants with TMD and 17 pain-free controls. Transcranial magnetic stimulation (TMS) was used to assess M1 cortical excitability. Correlations between clinical and psychosocial factors and cortical excitability measures were also evaluated. Patients with TMD showed significantly higher intracortical facilitation at 12ms (z = 1.98, p = 0.048) and 15ms (z = 2.65, p = 0.008) when compared to controls. Correlations revealed associations between intracortical facilitation and pain interference, sleep quality, depressive symptoms, and pain catastrophizing in the TMD group. Females with TMD exhibit heightened motor cortex intracortical facilitation in the hand representation, potentially indicating altered cortical excitability beyond the motor face area. This suggests a role for cortical excitability in TMD pathophysiology, influenced by psychosocial factors. Understanding cortical excitability in TMD may inform targeted interventions. Psychosocial variables may play a role in cortical excitability, emphasizing the multidimensional nature of TMD-related pain. Further research is needed to confirm and expand upon these findings, with potential implications for the management of TMD and related pain conditions.

The relationship between the oblique sagittal temporomandibular joint disc position and the volume surface area of the condyle in young TMD adults.

The present study aims to compare the volume surface area of the condyle, the horizontal condylar axial angle and the disc-condyle angle between temporomandibular disorder (TMD) and asymptomatic volunteers, explore and analyze the relationship between the temporomandibular joint (TMJ) disc position in oblique sagittal plane and the volume surface area of the condyle in young adults with TMD symptoms. 84 young adult volunteers were received TMJ examination by Magnetic Resonance Imaging (MRI) and Cone Beam Computed Tomography (CBCT). TMD and asymptomatic volunteers were 42 each. MRI was used to assess the position of TMJ disc in the oblique sagittal plane with the condyle apex method. CBCT data were used for three-dimensional (3D) reconstruction of condyle and the measurements of the horizontal condylar axial angle and the volume surface area of the condyle. The condylar volume surface area of the TMD group was smaller than that of the asymptomatic group (p < 0.05), the disc condyle angle was larger than that of the asymptomatic group (p < 0.05), and no significant difference was found in the horizontal condylar axial angle (p > 0.05). In terms of correlation, the volume surface area of the condyle were negatively correlated with the position of the articular disc in TMD patients (p < 0.05). This significant negative correlation suggests that the possibility of disc displacement can be considered when poor condylar morphology is found.

The association between orthodontic treatment and temporomandibular disorders diagnosis and disease characteristics.

The association between orthodontic treatment and temporomandibular disorders (TMD) has been contentious in the literature. To analyse the associations between orthodontic treatment and TMD diagnosis and diseases characteristics. This case-control study included 291 individuals, 192 TMDs and 99 controls. All patients underwent assessment based on a questionnaire and a clinical examination according to Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Differences in orthodontic treatment between TMDs and controls, as well as across different TMD diagnoses within the TMD group were analysed. Patients who underwent orthodontic treatment were compared to those who did not, regarding their trauma history, bruxism, aggressive teeth brushing, level of oral hygiene, pain scores, muscle tenderness scores and subjective sleep quality. Of the 291 participants, 119 (40.9%) underwent orthodontic treatment and 172 (59.1%) had no orthodontics experience. Orthodontic treatment included: mandibular orthodontic treatment (102 subjects) and maxillary orthodontic treatment (113 subjects) of those 47 used a headgear. Following multivariate analysis among TMDs, orthodontic treatment was associated with a good level of oral hygiene versus poor (Odds ratio [OR]: 5.17 [1.04-25.59]), lower number of tender muscles [OR = 0.84 (0.74-0.96)] and lower (better) Pittsburgh Sleep Quality Index (PSQI) scores (OR = 0.86 [0.76-0.97]). None of the studied parameters maintained a statistically significant association with orthodontic treatment in the multivariate analysis among the entire study population. Utilising a holistic approach, this study supports the main hypothesis that orthodontic treatment is not associated with TMD diagnosis and disease characteristics.

The association of gene polymorphisms in catechol-O'methyltransferase (COMT) and β2-adrenergic receptor (ADRB2) with temporomandibular joint disorders

ObjectiveTemporomandibular disorder (TMD) has a multifactorial etiology that includes environmental, psychological, and genetic factors. This study aimed to evaluate the possible relationship between polymorphisms in Catechol-O-methyltransferase (COMT) and β2-adrenergic receptor (ADRB2) genes with TMD. DesignThis observational case-control study included 80 patients and 70 healthy controls. The diagnosis of TMD was made using the diagnostic criteria for TMD and the following TMD categories were used for the case group: muscular TMD and articular TMD (disc displacement and arthralgia). A genotyping study of gene polymorphisms in COMT (rs 9332377) and ADRB2 (rs20530449) was performed from genomic DNA isolated from blood. The chi-square test was used to analyze the relationships. P < 0.05 was accepted as a significant difference. ResultsThe polymorphic TT and CT genotype for COMT (rs rs9332377) was significantly higher in the articular TMD group while the non-polymorphic CC genotype was significantly lower in the articular TMD group (P < 0.05). Regarding ADRB2 (rs20530449), the polymorphic GG genotype was similarly considerably more common in the articular TMD group (p < 0.05). In addition, the T allele in the COMT (rs rs9332377) gene was found to be significantly higher in the articular TMD group (p < 0.05). ConclusionsIn the Turkish population, gene polymorphisms in COMT (rs9332377) and ADRB2 (rs2053044) were associated with articular TMD. This study supports the hypothesis that changes in COMT and ADRB2 genes may play a role in temporomandibular joint pain and predisposition to TMD.

The effect of temporomandibular joint dysfunction on the craniocervical mandibular system: A retrospective study.

Temporomandibular disorders are the most common condition affecting the orofacial region, resulting in pain and dysfunction. This study aimed to elucidate the ambiguous association between cervical features and temporomandibular disorders by measuring the rotations between the skull-atlas, atlas-axis and mandible-atlas and examining the relationship between these rotations and temporomandibular disorders. Cone-beam computed tomography (CBCT) images from 176 patients, 97 females and 79 males with an average age of 25.7 years were used in this study. The patients were divided into two groups: those with joint dysfunction (n = 88) and those without (n = 88). The study employed various methods to determine rotations in the skull-atlas, atlas-axis and mandible atlas based on anatomical landmarks and measurements. These methods include the use of specific planes, angles and distances to identify and measure rotation. Data analysis was performed using the TURCOSA statistical software (Turcosa Analytics Ltd Co, Turkey, www.turcosa.com.tr). The results showed that the degree of rotation between the skull and the atlas was higher in the TMD group than in the control group (p < .001). Similarly, Atlas-axis rotation was significantly higher in the TMD group (p < .001). However, no significant difference was found between mandible atlas rotations in the two groups (p = .546). The study also found a significant difference between the direction of rotation between the atlas and axis and the direction of mandible atlas rotation (p < .001) as well as between skull and atlas rotations and mandible-atlas rotations (p < .001). Overall, the study suggests that there is a relationship between the skeletal structures of the cranio-cervico-mandibular system and TMD. Skull-atlas and atlas-axis rotations may play an important role in the aetiology of TMD in individuals with TMD. Therefore, it is important to evaluate rotations in the skull-atlas-axis region for the treatment of TMD.

Correlates of jaw functional limitation, somatization and psychological distress among different temporomandibular disorder diagnostic subtypes.

This study investigated the jaw functional status and severity of somatic/psychological symptoms in different Diagnostic Criteria for temporomandibular disorders (DC/TMD) diagnostic subtypes and established the correlates between jaw functional limitation, somatization, depression and anxiety. Data were accrued from consecutive 'first-visit' patients seeking TMD treatment at a university-based oral medicine/diagnosis clinic. Axis I physical TMD diagnoses were derived using the DC/TMD methodology and patients were categorized into pain-related (PT), intra-articular (IT) and combined (CT) TMD groups. Axis II measures were also administered and included the Jaw Functional Limitation Scale-20 (JFLS-20), Patient Health Questionnaire-15 and 9 (PHQ-15 and PHQ-9) and General Anxiety Disorder Scale-7 (GAD-7). Chi-square/Kruskal-Wallis tests and Spearman's correlation were employed for statistical evaluations (α = .05). The final dataset consisted of 772 TMD patients (mean age of 37.7 ± 15.9 years; 70.2% females). The prevalence of PT, IT and CT was 11.9%, 15.7% and 72.4%, respectively. Significant differences in functional jaw limitations, somatization, depression (CT, PT > IT) and anxiety (CT > PT, IT) were observed. Moderate-to-severe somatization, depression and anxiety were detected in 12.6%-15.7% of patients. For all three TMD groups, JFLS global scale/subscale scores were weakly associated with somatization, depression and anxiety scores (rs < 0.4). Moderate-to-strong correlations were noted between somatization, depression and anxiety (rs = 0.50-0.74). Functional jaw limitations were associated with painful TMDs but appear to be unrelated to somatization and psychological distress. Somatization and depression/anxiety were moderately correlated, underscoring the importance of somatic symptom screening when managing TMD patients.

Investigating the Reliability of Ultrasonography Measurements of Masticatory Muscles in subjects with and without Temporomandibular Disorders: An Intra-rater Reliability Study

Introduction: Ultrasonography is a common tool for assessing muscle morphology. This study aims to investigate the intra-rater reliability of ultrasonography measurements of the masseter and lateral pterygoid muscles (LPM) in subjects with and without temporomandibular disorder (TMD) and to compare the measurements between the two groups.&#x0D; Materials and Methods: A total of 30 individuals (15 subjects with TMD and 15 subjects without TMD) participated in the study. Imaging of the masseter muscle at rest and contraction, in addition to LPM, was performed using sonography in 2 sessions with a 2-day interval and the thickness of these muscles was measured. To assess the reliability, the intraclass correlation coefficient (ICC(3, 3)), standard error of measurement, minimal detectable change, and limits of agreement were used. Additionally, for the between-group comparison of measurements, the independent sample t-test was used. The Cohen d was used to determine the size of the differences.&#x0D; Results: ICC(3, 3) for intra-rater reliability of masseter thickness in rest and clenched positions and LPM were 0.89, 0.80, and 0.86 in the asymptomatic group, and 0.88, 0.80, and 0.90 in the TMD group, respectively. The values of absolute reliability parameters, such as standard error of measurement and minimal detectable change were in a small range. Additionally, compared to the asymptomatic group, the TMD group had thicker masseter muscle in the rest position and the effect size revealed a large difference between the groups. No significant differences were found between the groups for the thickness of the masseter muscle in contraction position and LPM.&#x0D; Conclusion: The results of the intra-reliability study revealed that ultrasonography is a reliable method to measure the thickness of the masticatory muscles in TMD subjects and asymptomatic subjects. Additionally, TMDs can change the thickness of the masticatory muscles.

Protective Effect of Long-Term Fermented Soybeans with Abundant Bacillus subtilis on Glucose and Bone Metabolism and Memory Function in Ovariectomized Rats: Modulation of the Gut Microbiota.

We investigated the effects of different types of long-term fermented soybeans (traditionally made doenjang; TMD) on glucose and bone metabolism and memory function in ovariectomized (OVX) rats. The rats were categorized into six groups: Control, cooked unfermented soybeans (CSB), and four TMDs based on Bacillus subtilis (B. subtilis) and biogenic amine contents analyzed previously: high B. subtilis (HS) and high biogenic amines (HA; HSHA), low B. subtilis (LS) and HA (LSHA), HS and low biogenic amines (LA; HSLA), and LS and LA (LSLA). The rats in the CSB and TMD groups fed orally had a 4% high-fat diet for 12 weeks. Rats in the Control (OVX rats) and Normal-control (Sham-operated rats) groups did not consume CSB or TMD, although macronutrient contents were the same in all groups. Uterine weight and serum 17β-estradiol concentrations were much lower in the Control than the Normal-control group, but CSB and TMD intake did not alter them regardless of B. subtilis and biogenic amine contents. HOMA-IR, a measure of insulin resistance, decreased with TMD with high B. subtilis (HSLA and HSHA) compared to the Control group. In OGTT and IPGTT, serum glucose concentrations at each time point were higher in the Control than in the Normal-control, and HSLA and HSHA lowered them. Memory function was preserved with HSHA and HSLA administration. Bone mineral density decline measured by DEXA analysis was prevented in the HSHA and HSLA groups. Bone metabolism changes were associated with decreased osteoclastic activity, parathyroid hormone levels, and osteoclastic activity-related parameters. Micro-CT results demonstrated that TMD, especially HSLA and HSHA, preserved bone structure in OVX rats. TMD also modulated the fecal bacterial community, increasing Lactobacillus, Ligalactobacillus, and Bacillus. In conclusion, through gut microbiota modulation, TMD, particularly with high B. subtilis content, acts as a synbiotic to benefit glucose, bone, and memory function in OVX rats. Further research is needed to make specific recommendations for B. subtilis-rich TMD for menopausal women.

Surface electromyography in the assessment of masticatory muscle activity in patients with pain-related temporomandibular disorders: a systematic review.

Temporomandibular disorders (TMD) are a set of painful conditions affecting the orofacial region that are prevalent and constitute the most frequent type of non-dental pain complaint in the maxillofacial area. Pain-related TMD (TMD-P) is characterized by ongoing pain in the masticatory muscles, the temporomandibular joint, or surrounding structures. Due to the multiple factors that contribute to the development of this condition, it can be challenging to accurately diagnose. One of the useful method for assessing patients with TMD-P is surface electromyography (sEMG). The aim of this systematic review was to provide a comprehensive overview of the current scientific literature on the evaluation of masticatory muscle activity (MMA) in individuals diagnosed with TMD-P, through the utilization of sEMG. To gather relevant information, electronic databases such as PubMed, Web of Science, Scopus, and Embase were searched using specific keywords including: "pain" AND ("temporomandibular disorder*" OR "temporomandibular dysfunction*") AND "surface electromyography" AND "masticatory muscle activity." The inclusion criteria were studies assessing MMA in patients with TMD-P using sEMG. The Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies was utilized to evaluate the quality of the studies that were included in the review. The search strategy identified 450 potential articles. Fourteen papers met the inclusion criteria. Global quality rating for significant part of the articles was weak. Most studies showed greater sEMG activity of the masseter (MM) and temporal anterior (TA) muscles at rest in TMD-P subjects than in the asymptomatic controls, while the MM and TA muscles were less active in the pain-related TMD group compared to the non-TMD group during maximal voluntary clenching (MVC). There were differences in MMA in the TMD-pain population compared to a healthy control group during various tasks. The diagnostic efficacy of surface electromyography in assessing individuals with TMD-P remains unclear.

Dimensional and Positional Characteristics of the Temporomandibular Joint of Skeletal Class II Malocclusion with and without Temporomandibular Disorders.

This study sought to evaluate dimensional and positional temporomandibular joint (TMJ) features in three-dimensions in skeletal class II malocclusion with and without temporomandibular disorders (TMDs). A total of 91 (182 joints) adult patients were divided into the following two groups: (1) Group I - TMD (n = 56; 112 joints) and (2) group II - non-TMD (n = 35; 70 joints). Dimensional and positional TMJ characteristics including glenoid fossae, mandibular condyles, and joint spaces were assessed using cone-beam computed tomography (CBCT). The mandibular fossa in the TMD group was significantly more lateral than in the non-TMD group, and the mandibular fossa anterior wall inclination to the horizontal plane showed a significantly more vertically inclined wall in the TMD group compared to the non-TMD group. Significantly vertical mandibular condylar changes in the form of less vertical inclination, more vertical position, and lower vertical dimension (height) in addition to more upward position within the joint space were found. The TMD group showed significantly decreased superior and posterior joint spaces in addition to significantly increased medial joint spaces. Patients with TMDs are associated with laterally positioned mandibular fossa with the more vertically inclined anterior wall. They are characterized by vertical mandibular condylar changes in the form of less vertical inclination, more vertical position, and lower vertical dimension (height) in addition to more upward positioning within the joint space is accompanied by a decrease in superior and posterior and an increase in medial joint spaces. The TMJ characteristics of skeletal class II make it more susceptible to TMDs and any orthodontic and/or surgical interventions in a direction possibly change these characteristics are to be considered.

Do intra-articular temporomandibular disorders show an association between physical bite function, self-perceived bite limitation and kinesiophobia? A case-control study

BackgroundLittle is known about the impact of intra-articular temporomandibular disorders (TMDs) on bite function, or how bite impairments in this subgroup relate to self-perceived bite limitation or kinesiophobia. This presents a challenge to practitioners involved in delivering care. ObjectivesTo determine what bite impairments are associated with intra-articular TMDs, and explore how these impairments relate to self-perceived bite limitations and kinesiophobia. DesignObservational, case-control study. MethodSixty participants (n = 30 intra-articular TMDs, n = 30 healthy controls) were recruited via convenience sampling. Bite function was explored using pain-free bite force and bite endurance/steadiness (submaximal bite hold) measures. Self-perceived bite function and kinesiophobia were evaluated via the Patient specific functional scale (PSFS) and the Tampa Scale for kinesiophobia of Temporomandibular disorders (TSK-TMD) respectively. Between-group data were compared and associations between physical bite impairments, self-perceived bite limitation and kinesiophobia were explored in the intra-articular TMD group. ResultsPain-free bite force was significantly impaired in the intra-articular TMD group (−108N, p < 0.01, d = 0.9), and this impairment demonstrated moderate association with degree of kinesiophobia (p < 0.01, r = −0.4). No significant between-group difference was observed for bite endurance or force steadiness (p > 0.05). No association was observed between pain-free bite force and self-perceived bite limitation, or self-perceived bite limitation and kinesiophobia (p > 0.05). ConclusionsImpaired pain-free bite force appears to be an important feature of intra-articular TMDs which should be considered within management. Kinesiophobia may be important to consider when assessing bite function in this subgroup. Future research is needed to guide optimal interventions and inform subsequent management guidelines.

Maximum bilateral bite strength and RMS EMG for the diagnosis of myogenic TMD

Aim: The study aimed to evaluate the accuracy of the maximum bilateral molar bite force and the Root Mean Square (RMS) Electromyography (EMG) index of the masticatory muscles in the maximum bilateral molar bite (MMBMax) of women with myogenic Temporomandibular Disorder (TMD) and asymptomatic. Methods: This is a cross-sectional study, composed of 86 women allocated to the TMD Group (n=43) and Control Group (n=43) diagnosis through the Diagnostic Criteria for Temporomandibular Disorders. The maximum bilateral molar bite force was evaluated using a bite dynamometer and the RMS EMG index of the masticatory muscles (anterior temporalis, masseter) during 5 seconds of the MMBMax task. Student t-test was used for data comparison between accuracy of the bite force and RMS EMG of masticatory muscles during the MMBMax. Results: The maximum bilateral molar bite force showed high accuracy (AUC=0.99) for the diagnosis of women with myogenic TMD and asymptomatic women, and the RMS EMG index evaluated during the MMBMax showed a moderate level of accuracy for all masticatory muscles (AUC=0.70 to 0.75). Conclusion: The bilateral bite dynamometer with a surface EMG during bilateral bite can be used to diagnose TMD in young women.