Gender differences in temporomandibular disorders in adult populational studies: A systematic review and meta-analysis

Minimum clinically important difference and substantial clinical benefit in patients with chronic temporomandibular disorders

BACKGROUND

Research on temporomandibular disorder (TMD) responsiveness is scarce and limited regarding patients' representativeness.

OBJECTIVE(S)

This study aimed to estimate minimum clinically important difference (MCID) and substantial clinical benefit (SCB) among a large and diverse patient population regarding sex and age.

METHODS

In this study, 162 patients participated from five hospitals. MCID and SCB in pain, functional disability and quality of life were examined with anchor-based methods. Patients' global impression of change was used as the anchor. Area under the curve (AUC) values were determined for testing accuracy. Changes from baseline and coefficient of variation by responsiveness status were calculated to explain the results of accuracy.

RESULTS

SCB was estimated to be 2.18 for the numeric rating scale (NRS) for pain (AUC: 0.80 [95% CI: 0.72-0.88]) in all patients and 2.50 in women (AUC: 0.81 [95% CI: 0.71-0.89]). The estimated SCB of NRS for discomfort (1.50) and Jaw Functional Limitation Scale for mastication (1.35) had wide CIs for AUCs. Likewise, the estimated MCIDs of NRS for pain (0.80) and NRS for discomfort (1.50) had wide CIs for AUCs. Among non-responders who did not achieve the MCID of NRS for pain, the coefficient of variation was very high for all outcomes other than the NRS for pain.

CONCLUSION

This study investigated the responsiveness of patients with TMD using a large and diverse patient sample. SCB in pain decrease can be used to assess the responsiveness of patients with TMD. Composite outcomes should be developed to estimate MCID.

Pain-free bite force in a healthy population: Within-session test-retest reliability in different sitting positions

BACKGROUND

Pain-free bite force (PFBF) is a promising measure to evaluate bite function in temporomandibular disorders (TMDs), yet the reliability of the measure is unknown.

OBJECTIVES

Establish the (1) within-session test-retest reliability of PFBF in a healthy population for a single and mean of three trials in supported and unsupported sitting; (2) standard error of measurement (SEM) and minimal detectable change (MDC).

METHODS

Thirty healthy participants (n = 15 female, mean [SD] age = 34.4 [11.0] years) completed two sessions (30-60 min apart) comprising three PFBF trials on each side, in both supported and unsupported sitting, to provide data for 60 (30 participants × two sides) test-retest assessments. Test-retest reliability for the first trial and mean of three trials in each position were determined using intraclass correlation coefficients (ICCs), before calculating the corresponding SEM and MDC for males (M) and females (F) respectively.

RESULTS

Within-session reliability was considered excellent for a single trial in supported sitting (ICC = 0.85; SEM M/F = 99/84 N; MDC M/F = 275/232 N) and unsupported sitting (ICC = 0.91; SEM M/F = 72/59 N, MDC M/F = 200/163 N), and for a mean of three trials in supported sitting (ICC = 0.89; SEM M/F = 66/79 N, MDC M/F = 182/220 N) and unsupported sitting (ICC = 0.92; SEM M/F = 64/59 N, MDC M/F = 177/164 N).

CONCLUSION

Single and a mean of three trials in supported and unsupported sitting appear reliable methods to measure PFBF in a healthy population. Testing PFBF using a mean of three trials in unsupported sitting appears superior over other methods though due to higher test-retest reliability, and lower SEM and MDC. Future studies should examine the reliability of PFBF in TMD populations.

Conceptualising TMD symptom burden in youths: Symptom duration, frequency, intensity and interference

OBJECTIVE

This study aimed to conceptualise Temporomandibular disorder (TMD) symptom burden and severity and explored their interrelationships with somatic symptoms and psychological distress.

METHODS

Participants were recruited from a local polytechnic. The quintessential five TMD symptoms (5Ts) of the Diagnostic Criteria for TMDs (DC/TMD) were appraised and extended to evaluate the duration, frequency, intensity and interference of discrete TMD symptoms. Global TMD severity (GS) was computed by totaling the points for all TMD symptoms and dimensions. TMD (TS) and somatic symptom (SS) burden were assessed based on the Somatic Symptoms Scale-8, while psychological distress was measured with the Depression, Anxiety and Stress Scales-21. Statistical analyses were performed using Kruskal-Wallis/Dunn tests and Spearman's correlation (α = .05).

RESULT

Of the 366 eligible participants (mean age 19.1 ± 2.3 years), 51.4% were 5Ts-negative and 48.6% were 5Ts-positive. Among the 5Ts-positive individuals, 25.3%/64.0% were 'bothered a little' whereas 4.5%/10.7% were 'bothered a lot' by TMD pain/headache. Correspondingly, 32.6%/12.4%/5.1% were 'bothered a little' while 2.8%/2.8%/1.1% were 'bothered a lot' by TMJ sounds/closed/open locking. TS burden was moderate-to-strongly correlated to aggregate symptom duration, frequency, intensity, interference, GS and SS burden (rs = .50-.88). While TS burden and GS were weakly associated with psychological distress (rs = .18-.36), SS burden was moderately related to depression, anxiety and stress (rs = .47-.53).

CONCLUSIONS

TS burden can serve as a proxy for global TMD severity and may be more meaningful than the mere presence of TMD symptoms in clinical and research settings.

Temporomandibular disorder pain is associated with increased sick leave and reduced health related quality of life

BACKGROUND

Temporomandibular disorders (TMD) are the most common reason for chronic pain in the orofacial area and significantly impact the lives of those affected. The role of lifestyle factors in TMD, however, remains less explored. This cohort study aims to estimate TMD prevalence by addressing potential selection biases and to evaluate the association between TMD and lifestyle factors with a specific focus on sick leave and health related quality of life.

METHODS

By linking data on TMD in the general population in Västerbotten, northern Sweden (n = 180,000) to health survey data (n = 120,000), information on sociodemographic factors and quality of life was available for 52,961 individuals (50.6% women) with a mean age of 53 years. We applied inverse probability weighting to adjust for selection bias and Poisson regression to explore associations with TMD.

RESULTS

TMD prevalence was 9.2% during the study period, being higher in women (12.9%) than men (5.4%). Weighting for varying visiting frequencies did not affect TMD prevalence (average difference 0.4% points). Individuals with TMD, especially women, reported more sick leave and use of pain medication, with a significant association between TMD and increased sick leave (prevalence ratio 1.89, 95% CI: 1.78-2.01) among both women and men. In addition, TMD was associated with a lower health related quality of life (p < 0.001).

CONCLUSION

The association of TMD with sick leave highlights the condition's profound impact on the lives of affected individuals. These findings underscore the influence of TMD on work life and the burden of TMD on the societal level.

SIGNIFICANCE STATEMENT

The findings provide insight into how TMD affect individuals, by incorporating lifestyle factors, social determinants and the impact of sick leave at a population level. By incorporating these areas into the study of TMD, we can deepen our understanding of how TMD affects individuals' lives. This approach may also create opportunities to develop more comprehensive strategies to address TMD, focusing on broader implications beyond the clinical symptoms.

Somatic and temporomandibular disorder symptoms - Idioms of psychological distress in Southeast Asian youths

OBJECTIVE

To evaluate the prevalence/severity of somatic and temporomandibular disorder (TMD) symptoms in Southeast Asian youths and determine their associations with psychological distress.

METHODS

Demographic information, Patient Health Questionnaire-15 (PHQ-15), Fonseca Anamnestic Index (FAI), and Depression, Anxiety, Stress Scale-21 (DASS-21) responses were gathered electronically and analyzed using non-parametric statistical and logistic regression analysis (p < 0.05).

RESULTS

Of 400 youths (mean age 18.7 ± 1.7 years; 52.3% females), 65.0%/47.0% reported somatic/TMD symptoms, and 10.5% had TMDs. Significant differences in psychological distress were observed among the varying severity of somatic/TMD symptoms. Correlations between PHQ-15/FAI and DASS-21 scores were weak to moderately strong (rs = 0.30-0.61). Stepwise logistic regression indicated that female gender, TMD symptoms, and stress were risk factors for somatic symptoms, while somatic symptoms and stress were probable factors for TMDs.

CONCLUSION

Somatic and TMD symptoms are common in Southeast Asian youths and may be a manifestation of psychological distress.

Psychometric properties of the Indonesian Fonseca anamnestic index and the presence/severity of temporomandibular disorders among Indonesian young adults

OBJECTIVE

The psychometric properties of the Indonesian FAI (FAI-I) and presence/severity of temporomandibular disorders (TMDs) among Indonesian young adults were explored.

METHODS

The FAI-I was developed following the INfORM guidelines and used to determine the presence/severity of TMDs. Internal consistency/test-retest reliability were examined with Cronbach's alpha/intra-class correlation (ICC) coefficients. Construct/criteria validity were established by correlating (Spearman) the FAI-I to the five major TMD symptoms (5 Ts) and OHIP-14 (p < 0.05).

RESULTS

Five hundred-one participants (mean age 19.73 ± 1.27 years; 75.2% women) were recruited from a local University. Of these, 40.7% had no TMD, while 49.9%, 8.8%, and 0.6% had mild, moderate, and severe TMD. While Cronbach's α = 0.57 and ICC = 0.72, correlation coefficients to total 5 Ts and OHIP-14 were 0.53 and 0.47, respectively.

CONCLUSION

The FAI-I had low internal consistency, good test-retest reliability, and good validity. Moderate-to-severe TMD was experienced by 9.4% of the young adults examined.

Elevated pain sensitivity is associated with reduced rapid eye movement (REM) sleep in females with comorbid temporomandibular disorder and insomnia

OBJECTIVE

Patients with chronic pain disorders, including Temporomandibular Disorders (TMDs) endorse high levels of sleep disturbances, frequently reporting reduced sleep quality. Despite this, little is known about the effect that daytime pain has on the microstructure and macro-architecture of sleep. Therefore, we aimed to examine the extent to which daytime pain sensitivity, measured using quantitative sensory testing (QST), is associated with objective sleep parameters the following night, including sleep architecture and power spectral density, in women with TMD.

METHODS

144 females with myalgia and arthralgia by examination using the Diagnostic criteria for TMD completed a comprehensive QST battery consisting of General Pain Sensitivity, Central Sensitization Index, and Masseter Pressure Pain Threshold assessments. Polysomnography was collected the same night to measure sleep architecture and calculate relative power in delta, theta, alpha, sigma, and beta power bands.

RESULTS

Central Sensitization (B = -3.069, P = .009), General Pain Sensitivity Indices (B = -3.069, P = .007), and Masseter Pain Pressure Threshold (B = 0.030, P = .008) were significantly associated with lower REM% both before and after controlling for covariates. Pain sensitivity measures were not significantly associated with relative power in any of the spectral bands nor with any other sleep architectural stages.

CONCLUSIONS

Our findings demonstrate that higher generalized pain sensitivity, masseter pain pressure threshold, as well as central sensitization were associated with a lower percentage of REM in participants with myofascial pain and arthralgia of the masticatory system. These findings provide an important step toward understanding the mechanistic underpinnings of how chronic pain interacts with sleep physiology.

Significance of radiographic temporomandibular degenerative joint disease findings

The field of orthodontics has seen a recent increase in the number of patients over the age of 50 seeking treatment and also an increase in the use of cone beam technology. Similar to other joints in the body, the temporomandibular joint (TMJ) is associated with age-related degeneration. However, unlike other joints, degeneration of the TMJ is rarely symptomatic and when there is pain, it is usually self-limiting. In this article, we will review: a) the incidence and prevalence of TMJ degenerative diseases, b) similarities and differences of TMJ vs knee degenerative diseases, and c) current treatment recommendations for TMJ degenerative diseases. In the vast majority of people, radiographic evidence of TMJ degeneration is an incidental finding. Future longitudinal research is needed to follow the natural course of TMJ degenerative patients.

Exploring the causal effects of sleep characteristics on TMD-related pain: a two-sample Mendelian randomization study

OBJECTIVES

The study was to explore the causal effects of sleep characteristics on temporomandibular disorder (TMD)-related pain using Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

Five sleep characteristics (short sleep, insomnia, chronotype, snoring, sleep apnea) were designated as exposure factors. Data were obtained from previous publicized genome-wide association studies and single nucleotide polymorphisms (SNPs) strongly associated with them were utilized as instrumental variables (IVs). TMD-related pain was designed as outcome variable and sourced from the FinnGens database. MR analysis was employed to explore the causal effects of the five sleep characteristics on TMD-related pain. The causal effect was analyzed using the inverse variance-weighted (IVW), weighted median, and MR-Egger methods. Subsequently, sensitivity analyses were conducted using Cochran's Q tests, funnel plots, leave-one-out analyses, and MR-Egger intercept tests.

RESULTS

A causal effect of short sleep on TMD-related pain was revealed by IVW (OR: 1.60, 95% CI: 1.06-2.41, P = 0.026). No causal relationship was identified between other sleep characteristics (insomnia, chronotype, snoring, sleep apnea) and TMD-related pain.

CONCLUSIONS

Our study suggests that short sleep may increase the risk of TMD-related pain, while there was no causal relationship between other sleep characteristics and TMD-related pain. Further studies are warranted to deepen and definitively clarify their relationship.

CLINICAL RELEVANCE

These findings reveal that the short sleep may be a risk factor of TMD-related pain and highlight the potential therapeutical effect of extending sleep time on alleviating TMD-related pain.

Prevalence of temporomandibular disorders and their associated factors in Confucian heritage cultures: A systematic review and meta-analysis

BACKGROUND

Temporomandibular disorders (TMDs) may be an 'idiom' of psychological distress in Confucian heritage cultures (CHCs).

OBJECTIVES

This systematic review/meta-analysis estimated the prevalence of TMDs in CHCs and compared the differences in TMD occurrence between time periods and age groups. Additionally, the associated biopsychosocial risk factors were also examined.

METHODS

The study protocol was developed a priori following the PRISMA guidelines and Joanna Briggs Institute systematic review methodology (CRD42021245526). Electronic searches of seven databases were conducted from January 2002 to Dec 2021. Reference lists of identified studies were hand-searched for additional articles. Study selection, quality assessment, and data extraction were done. Meta-analysis was performed using the RevMan 5.4 software.

RESULTS

Forty-eight articles were included in the systematic review. Overall prevalences were: TMDs-15% (95% CI: 15-16%); TMD pain-8% (95% CI: 7-9%); TMJ sounds-24% (95% CI: 21-27%); and TMJ locking-7% (95% CI: 1-13%). While TMD prevalence appeared to have declined from 2002 to 2011 to 2012-2021, the occurrence of TMD pain, TMJ sounds, and locking increased marginally or remained constant. TMD prevalence in children/adolescents was 18% (95% CI: 14-22%) and 17% (95% CI: 16-18%) among adults. Significant associations between TMDs and bruxism/psychological distress/education levels were specified by 73%/90%/88% of the relevant studies.

CONCLUSIONS

TMDs are prevalent in CHCs and a slight increase in TMD pain (2%) and TMJ sounds (8%) were discerned over the past two decades. TMDs are related to a myriad of biopsychosocial variables, particularly psychological distress, and these factors must be addressed within the cultural context of patients.

Effectiveness of a home exercise program when added to a conventional physiotherapy program in patients with temporomandibular disorders: A comparative study

OBJECTIVE

This study aimed to investigate the effect of a home exercise program on pain and quality of life (QoL) in TMD.

METHODS

Twenty patients were included in the study. The Group A received both a home exercise program and a physiotherapy program, while only a physiotherapy program was given to the Group B. Pain was measured using the Visual Analogue Scale (VAS) and QoL using the Short-Form 36 (SF-36).

RESULTS

Pain decreased in both groups (p < 0.05). Among the SF-36 domains, bodily pain, vitality and social functioning scores improved in the Group A, while only the bodily pain parameter improved in the Group B (p < 0.05). On between-group comparison, the positive effect on pain and quality of life was greater in the Group A (p < 0.05).

CONCLUSION

The addition of a home exercise program to the conventional physiotherapy program provided greater improvement in pain and QoL in patients with TMD.

A translation and validation of the French version of the Gothenburg Trismus Questionnaire 2 (F-GTQ-2)

BACKGROUND

Limitation of mouth opening, widely known as trismus, is a major symptom altering quality of life in individuals presenting from temporomandibular joint disorder or head and neck cancer. A French-language instrument addressing jaw opening limitation following treatment for head and neck cancer (HNC) or temporomandibular joint disorder (TMD) is lacking.

OBJECTIVE

The aim of this study was to translate and validate the Gothenburg Trismus Questionnaire-2 (GTQ-2) into French.

METHODS

A French translation of the GTQ-2 was performed according to established international guidelines, leading to the French-GTQ-2 (F-GTQ-2). The validation study included 154 participants with trismus (minimum interincisal opening of ≤35 mm) following treatment for TMD or HNC and 149 age-matched participants without trismus. All participants completed the F-GTQ-2 and participants with trismus completed additional health-related quality of life questionnaires to allow for analysis of convergent validity.

RESULTS

The F-GTQ-2 demonstrated retained psychometric properties with Cronbach's alpha values above 0.70 for the domains, jaw-related problems, eating limitations, facial pain and somewhat lower for muscular tension (0.60). Mainly moderate correlations were found when comparing the F-GTQ-2 to other instruments, which was in line with the pre-specified hypotheses, indicating satisfactory convergent validity. Discriminant validity was found with statistically significant differences in all domains of the F-GTQ-2 between trismus and non-trismus participants.

CONCLUSION

The F-GTQ-2 can be considered a reliable and valid instrument to assess jaw-related difficulties in individuals with trismus due to HNC or TMD.

Prevalence and associations of temporomandibular disorders in older Brazilian adults

OBJECTIVE

The objective of the study was to estimate the prevalence of temporomandibular disorders (TMD) and describe associations in a representative sample of community-dwelling older Brazilian adults.

BACKGROUND

TMD cause recurrent or chronic pain and dysfunction with substantial impacts on quality of life, but little is known of their occurrence and associated factors among older adults.

MATERIALS AND METHODS

This was a cross-sectional study using data from the second wave of the Brazilian Longitudinal Study of Aging, a nationally representative sample of older Brazilian adults aged 50 or older. The presence of temporomandibular disorder symptoms was measured by the Fonseca Anamnestic Index. Independent variables included sociodemographic characteristics, general health conditions and self-reported oral health measures. The association between the independent variables and TMD symptoms was evaluated using logistic regression models.

RESULTS

Complete information for the variables of interest was available for 9391 individuals. The overall prevalence of TMD symptoms was 18.0% (95% CI 14.4-22.1). Relative to older adults aged 50-59 those in all age categories had lower odds of TMD symptoms. Individuals with depression, pain, sleep problems and self-reported poor general health had higher odds of reporting TMD symptoms. None of the oral health measures were related to TMD.

CONCLUSION

The prevalence of TMD symptoms among Brazilian older adults is associated with demographic and general health conditions, but not with dentition status.

Temporomandibular disorder and somatic symptoms: Relations to 'fear of missing out' and other negative emotional states

OBJECTIVE

The association between the 'fear of missing out (FOMO)' and physical symptoms has not been widely explored. This study aimed to investigate the relationship between FOMO and other negative emotions with Temporomandibular disorder (TMD) and somatic symptoms in young adults. The correlations between the various physical and emotional variables were also established.

MATERIAL AND METHODS

TMD and somatic symptoms were appraised with the Short-form Fonseca Anamnestic Index, quintessential five TMD symptoms of the Diagnostic Criteria (DC)/TMD, and Patient Health Questionnaire-15. FOMO and other negative emotional states were assessed with the FOMO Scale and Depression, Anxiety, Stress Scales-21 (DASS-21). Data were evaluated using non-parametric tests/correlation and regression analysis (α = 0.05).

RESULTS

While only negative affectivity (total DASS), anxiety, and stress differed significantly between those without and with TMDs, significant variances in FOMO and all DASS-21 constructs were discerned between individuals without and with somatization.  Conclusions: Individuals with orofacial pain and more severe somatic symptoms have higher levels of negative emotions including FOMO. While somatization increased the prospect of TMDs, being female, presence of TMDs, and negative affectivity were risk factors for somatization in young adults.

CLINICAL RELEVANCE

Asian young adults appear to be disposed to somatization, and TMDs may be a form of functional somatic syndromes. Recognition of somatic symptoms and emotional distress, including FOMO, is essential for person-centric TMD care.

Effects of athletic tape on orofacial pain and jaw movements after 24 hours of use: a randomized clinical trial

PURPOSE

To analyze the sensation of pain and the range of mandibular movements of adult individuals with temporomandibular disorder, before and after the application of the athletic tape.

METHOD

This is a double-blind randomized clinical trial, in which 22 adults with temporomandibular disorder participated, randomly allocated into two groups, with group A comprising 10 women and one man (mean age 28.2±8.3 years) and group B comprising nine women and two men (mean age 26.2±3.9 years). Group A was submitted to the application of the athletic tape on the masseter with 40% stretch and the group B to the application of the athletic tape on the masseter without stretching. All participants underwent the application of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Pain threshold assessment was performed using an algometer to apply pressure to measurement points. The measurement of mandibular movements was performed using a caliper. The athletic tape was glued using the I technique, with a fixed point over the insertion and a movable point over the origin of the masseter muscle. Participants remained with the athletic tape for 24 hours and were re-evaluated.

RESULTS

There was pain relief in the group A in the temporomandibular joint on the right and at the origin of the masseter on the left. The group B showed a reduction in pain in the left anterior temporal region. No differences were found in mandibular movements after intervention, as well as no difference was found in the comparison by groups.

CONCLUSION

The use of the athletic tape over the masseter muscle, with stretching, for 24 hours produced relief from the sensation of pain, on the origin of the right masseter and in the right temporomandibular joint, and, without stretching, in the left anterior temporal muscle. There was no difference in the range of mandibular movements.

Climate temperature and seasonal influences on the prevalence of temporomandibular disorders in South Korea

This study aimed to explore seasonal variations in temporomandibular disorder (TMD) prevalence in South Korea, utilizing nationwide population-based big data. Data corresponding to the Korean Standard Classification of Diseases code of K07.6, which identifies TMD, were extracted from the Health Insurance Review and Assessment Service online platform for the period from 2010 to 2022. Additionally, we integrated these data with climate temperature records from the Korean Meteorological Administration. We subsequently conducted a statistical analysis of TMD patient data on a monthly and seasonal basis over the past 13 years to assess prevalence. Over the past 13 years, the number of TMD patients in Korea has steadily increased. The prevalence of TMD rose from 0.48% (224,708 out of a total population of 50,515,666) in 2010 to 0.94% (482,241 out of a total population of 51,439,038) in 2022, marking a 1.96-fold increase. Among children under 10 years of age, no significant differences were observed in TMD prevalence between boys and girls. However, a distinct female predominance emerged after the age of 10, with an average female-to-male ratio of 1.51:1. The peak prevalence of TMD occurred in individuals in their 20 s, followed by adolescents in their late 10 s. The majority of TMD patients were concentrated in Seoul and Gyeonggi province, with metropolitan areas accounting for 50% of the total patient count. Seasonally, TMD patient numbers showed no significant increase in winter compared with spring or summer. The temperature difference, defined as the absolute difference between the highest and lowest temperatures for each month, showed a positive correlation with TMD patient counts. A greater temperature difference was associated with higher patient counts. The strongest correlation between temperature differences and TMD patient numbers was observed in winter (r = 0.480, p < 0.01), followed by summer (r = 0.443, p < 0.01), and spring (r = 0.366, p < 0.05). Temperature differences demonstrated a significantly stronger correlation with the increase in the number of TMD patients than absolute climate temperatures. This aspect should be a key consideration when examining seasonal trends in TMD prevalence in South Korea.

Anxiety mediates association between sex and jaw function limitation in temporomandibular disorder patients from China

Aim

The objective of this study is to explore the relationship between sex and jaw function and to test whether anxiety mediates the causal relationship between sex and jaw function in temporomandibular disorders (TMDs) patients.

Methods

A total of 488 participants with TMD were included in the analysis. Demographic data were collected. Generalized anxiety symptoms and anxiety severity were initially assessed using the GAD-7 questionnaire. And jaw function limitation was measured using the JFLS-8 scale. A directed acyclic graph (DAG) was used in this study to evaluate the hypotheses. Mediation analysis was conducted to explore causality and to calculate the total effect, natural direct effect (NDE) and natural indirect effect (NIE).

Results

In TMD patients, there was a significant association between female and jaw function (r = 0.17, p < 0.001), female and anxiety (r = 0.15, p = 0.002), anxiety and jaw function (r = 0.35, p < 0.001). In addition, sex can directly lead to differences in impaired jaw function (NDE: 3.719, 95% CI: 1.619-5.828, p < 0.001), and can also be causally related to jaw function through anxiety (NIE: 1.146, 95% CI: 0.267-2.024, p = 0.011). And the total effect was 4.865 (95% CI, 2.709-7.029, p < 0.001).

Conclusion

A causal mechanism was found that anxiety acts as a mediator of sex effects on jaw function. Therefore, psychological factors need to be taken into account in the treatment of female TMD patients. Further clinical trials are needed to explore whether psychotherapy is more beneficial to improve jaw function in female TMD patients.

Clinical effect of digitalized designed and 3D-printed repositioning splints in the treatment of anterior displacement of temporomandibular joint disc

OBJECTIVE

To compare the treatment effectiveness of digitized and 3D-printed repositioning splints with that of conventional repositioning splints in the treatment of anterior displacement of the temporomandibular joint disc.

METHODS

This retrospective study included 96 patients with disc displacement of the anterior temporomandibular joint. They were treated with either digitally designed and 3D-printed repositioning splints or traditional splints and followed up for at least six months. Changes in signs and symptoms such as pain and mouth opening before and after treatment were recorded to evaluate treatment outcomes.

RESULTS

During the first month of treatment, both the digitally designed and 3D-printed repositioning splint groups (Group B) and the traditional repositioning splint group (Group A) showed significant increases in mouth opening, with increases of 4.93 ± 3.06 mm and 4.07 ± 4.69 mm, respectively, and there was no significant difference between the two groups. Both groups had a significant reduction in visual analog scale (VAS) pain scores, with Group B showing a greater reduction of 1.946 ± 1.113 compared to 1.488 ± 0.978 in Group A (P < 0.05). By the sixth month, Group B's mouth opening further improved to 38.65 ± 3.22 mm (P < 0.05), while Group A's mouth opening did not significantly improve. Regarding pain, Group A's VAS score decreased by 0.463 ± 0.778 after one month, and Group B's score decreased by 0.455 ± 0.715; both groups showed significant reductions, but there was no significant difference between the two groups.

CONCLUSION

Compared with traditional repositioning splints, digitally designed and 3D-printed repositioning splints are more effective at reducing patient pain and improving mouth opening. 3D-printed repositioning splints are an effective treatment method for temporomandibular joint disc displacement and have significant potential for widespread clinical application.

Comorbidities between temporomandibular disorders and somatization in young adults: exploring links with personality, emotional, and sleep disturbances

OBJECTIVE

The comorbidities between temporomandibular disorders (TMDs) and somatization and their associations with personality traits, emotional disorders, and sleep disturbances were investigated.

STUDY DESIGN

Adults aged 18 to 24 years completed an electronic survey encompassing TMD symptoms (5Ts), Patient Health Questionnaire-15, Big Five Personality Inventory-10, Depression Anxiety Stress Scales-21, and Pittsburgh Sleep Quality Index. Data were assessed using non-parametric tests/correlation analysis and logistic regression analysis (α = 0.05).

RESULTS

The sample comprised 365 participants, of whom 22.2% and 19.5% were 5Ts-negative without and with somatization, respectively, and 18.1% and 40.3% were 5Ts-positive without and with somatization, respectively. Significant differences in neuroticism, distress, depression, anxiety, stress, and sleep quality were observed between 5Ts-negative participants with somatization and 5Ts-positive participants with somatization compared with 5Ts-negative participants without somatization and 5Ts-positive participants without somatization. Distress, anxiety, stress, and sleep were moderately correlated with somatic but not TMD symptoms (rs = 0.45-0.52).

CONCLUSIONS

Irrespective of whether they had TMDs, participants with somatization exhibited heightened levels of neuroticism and emotional and sleep disturbances.

Prevalence of Temporomandibular Disorders (TMD) in Dental Patients at a Specialized Regional Medical Center in Italy

BACKGROUND AND AIM

This study aimed to evaluate the prevalence of temporomandibular disorders (TMDs) in a sample of general dental patients seeking dental treatments in a northeastern Italian university clinic.

MATERIALS AND METHODS

Records of all patients presented for the first time to the dental division of Maggiore Hospital, Italy, between January 1, 2016, and December 31, 2017, were collected. Patients comprised those presenting to the dental clinics for non-TMD complaints, who, upon general examination, were found to have TMD signs and were referred for TMD evaluation. Data were extracted and analyzed, retrospectively. The prevalence of TMDs, age, gender, signs, and symptoms were evaluated.

RESULTS

Out of the 18,774 patients studied, 284 had signs of TMD. Women predominance was evident (73%), and patients aged 45-50 were the most frequent sub-population within the TMD population. Clicking was the most commonly present symptom (26.8%), and arthralgia was most commonly diagnosed among this sample (30.7%). A considerable number of patients suffered from muscular disease (myalgia and myofascial pain with 10.1% and 20.7% of the patients, respectively). Significant associations were found among those with myofascial pain on the one hand and degenerative disease and disc displacement with reduction, on the other hand. Furthermore, disc displacement with reduction on one side was associated with displacement without reduction on the other side.

CONCLUSION

A considerable number of patients presenting with dental complaints may have asymptomatic TMDs. This highlights the importance of systematic screening of dental patients for TMDs as part of general assessment.

Evaluation of the mandibular condylar bone microarchitecture in people living with HIV

OBJECTIVES

People living with HIV (PLWH) have been shown to have lower bone density at the spine, hip, and radius. However, whether a similar bone phenotype is seen in craniofacial bones is not known. The goal of this study was to evaluate the bone microarchitecture of the mandibular condyle in PLWH.

METHODS

We recruited 212 participants, which included 88 HIV-negative participants and 124 PLWH on combination antiretroviral therapy with virological suppression from a single academic center. Each participant filled out a validated temporomandibular disorder (TMD) pain screening questionnaire and had cone beam computed tomography (CBCT) of their mandibular condyles. Qualitative radiographic evidence of temporomandibular joint disorders-osteoarthritis (TMJD-OA) assessment and quantitative microarchitecture analysis of their mandibular condylar bones were conducted.

RESULTS

There was no statistically significant difference in either self-reported TMD or in radiographic evidence of TMJD-OA in PLWH compared with HIV-negative controls. Linear regression analysis revealed that positive HIV status remained significantly associated with increased trabecular thickness, decreased cortical porosity, and increased cortical bone volume fraction after adjusting for race, diabetes, sex, and age.

CONCLUSION

PLWH have increased mandibular condylar trabecular bone thickness and cortical bone volume fraction compared with HIV-negative controls.

Objectively measured adherence may affect side effects of mandibular advancement therapy in subjects with obstructive sleep apnea

PURPOSE

The purpose of this study was to determine if objectively measured adherence to oral appliance (OA) treatment may affect dental changes and temporomandibular disorders (TMD) in patients with obstructive sleep apnea (OSA).

METHODS

The original study group consisted of adults with OSA who were referred for OA therapy. Eight indicators of subjective side effects of using OA (temporomandibular joint (TMJ) and muscle pain, pain in teeth, jaw stiffness in the morning, clicking, dry mouth, hypersalivation, gingival irritation) were evaluated by a questionnaire. Three occlusal indicators (overjet, overbite, molar occlusion) and clinical TMD signs (TMJ pain, muscle pain, clicking, jaw deviation on opening) were evaluated at baseline and at the 3-, 6-, and 12-month follow-up. In addition, objective adherence monitoring for OA was registered. Statistical analyses included the chi-square test, Fisher's exact test, paired sample t-test, and linear regression analyses.

RESULTS

A total of 58 adults with OSA were referred for OA therapy. Mean (SD) age was 50.7 (11.7) and mean apnea-hypopnea index (AHI) was 19.5 (10.0). At 1-year follow-up, the study group consisted of 28 men and 12 women. Overjet but not overbite reduced significantly after 1-year OA therapy. The average nightly wear of OA was related to overjet and overbite reduction, and to TMD signs. Hypersalivation, dry mouth, and tooth discomfort were the most common subjective side effects of OA therapy.

CONCLUSION

There was a time-dependent relationship with the nightly wear of OA and reduction in overjet and overbite, and clinical TMD signs. With 60% of mandibular advancement, dental changes and TM-disorders were considered mild/minor in the 1-year study period.

The epidemiological profile of temporomandibular joint disorders in the Tunisian population: A cross-sectional study

Objective

This study aimed to explore the prevalence, signs, and symptoms of different types of TMD (Temporomandibular joint disorders) disorders in Tunisian patients.

Methods

A retrospective cross-sectional study was conducted using the clinical records of patients from the Department of Functional Exploration, Pain, and Orofacial Dysfunction of the Dental Clinic of Monastir.

Results

TMD is associated with a female predominance, with a peak prevalence among those aged between 20 and 40 years. Pain and a limited range of motion were significantly more prevalent in women (p = 0.019 and p = 0.012, respectively). Clicking sounds were the most frequent joint noises (38.2 %). Crepitus was more prevalent among older adults (33 %). Of the different types of TMD, disk displacement with reduction was the most prevalent (n = 216, 39 %). Sleep bruxism was more prevalent than awake bruxism (20.7 % VS 9.5 %). Due to the heterogeneous TMD signs and symptoms, patients tend to seek medical attention from various specialties (e.g. neurology and otolaryngology).

Conclusion

The prevalence of different types of TMD, and the different signs and symptoms varied depending on sociodemographic characteristics, such as sex, age and lifestyle. Diagnosis is challenging and TMD may be confused with other orofacial pain conditions.

Examination of Conditioned Pain Modulation in Myofascial TMD With Consideration of Temporal Summation

Research on myofascial temporomandibular disorder (mTMD) has often focused on potential dysfunction in endogenous pain modulation. However, studies on the specific inhibitory and facilitatory components of endogenous pain modulation using conditioned pain modulation (CPM) and temporal summation of second pain (TSSP) have shown mixed results. This study aimed to 1) examine whether women with mTMD demonstrated efficient CPM compared to controls; 2) explore the association between independent measures of CPM and TSSP in women with mTMD relative to controls; and 3) determine whether resulting modulatory profiles differentially predicted pain intensity among cases. All participants were recruited from dental clinics. Cases were women who met the research diagnostic criteria for mTMD. Controls did not have facial pain on exam and were selected to be sociodemographically similar to cases. CPM and TSSP were assessed via independent psychophysical protocols. CPM was examined in linear mixed models predicting pain thresholds adjusted for age and stratified by TSSP. Mean CPM was estimated at a 2.2 (SD = 2.8) degree increase in pain thresholds (P ≤ .001), similar in cases and controls (P = .67). CPM was less efficient in cases with enhanced TSSP (P = .031), but not in controls. Although the double-pronociceptive profile of both low CPM and high TSSP trended higher among cases than controls, it did not predict higher levels of pain intensity among cases. This study does not support deficient inhibitory endogenous pain modulation in mTMD, but results suggest that inhibitory and facilitatory pain modulation should be examined concomitantly in the study of endogenous pain modulation. PERSPECTIVE: This manuscript presents a novel examination of inhibitory modulation by the level of facilitatory modulation in mTMD. The findings and approach may prove useful for mechanistic researchers studying endogenous pain modulation and clinical researchers seeking to jointly examine conditioned pain modulation and temporal summation in future research on chronic pain.

Impact of the COVID-19 pandemic on clinical and psychological aspects of temporomandibular disorders

BACKGROUND

The Coronavirus 2019 disease (COVID-19) caused drastic changes in people's lifestyle that affected TMD characteristics through its physical and psychological influences. The aim of this study was to define the clinical and psychological characteristics of a large group of well-defined TMD patients and seek their differences between before and during the COVID-19 pandemic to establish points of care to be emphasized in the post-pandemic era.

METHODS

TMD patients diagnosed by the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) aged ≥ 18 were analyzed. Samples between September, 2017 to July, 2019 (n = 455) and March, 2021 to June, 2022 (n = 338) were collected to represent before and during COVID-19, respectively. The Graded Chronic Pain Scale (GCPS) and Symptom Checklist-90-Revision (SCL-90-R) were used to evaluate disability levels and psychological status. Clinical indices were compared between COVID periods and factors related to higher pain levels were investigated according to pandemic period.

RESULTS

More patients reported pain on palpation of the masticatory muscles during the pandemic (p = 0.021) while the number decreased for neck muscles (p = 0.001) and TMJ (p < 0.001) areas. Patients reporting nocturnal bruxism (23.3-29.6%) and clenching (45.1-54.7%) significantly increased during the pandemic. TMD patients with pain without disability were more common during the pandemic regardless of pain intensity (p < 0.001). The number of patients expressing interference in daily activities decreased drastically during COVID-19 regardless of disability level (p < 0.001). Factors associated with higher than moderate pain intensity (CPI ≥ 50) were insomnia (odds ratio [OR] = 1.603, p = 0.047) and somatization (OR = 1.082, p < 0.001) before the pandemic. During the pandemic, age (OR = 1.024, p = 0.007), somatization (OR = 1.070, p = 0.006), and paranoid ideation (OR = 1.117, p = 0.003) were significantly associated with higher pain intensity.

CONCLUSIONS

The results of our study underline the importance of evaluating psychological profiles of TMD patients, especially somatization, paranoid ideation and psychoticism, in exceptional situations that may cause a change in individual mental status. This will lead to a better understanding of the individual TMD patient and help in planning personalized treatment strategies that will assist the patient in adjusting to changes occurring in special environments such as the COVID-19 pandemic.

Are orofacial pain and xerostomia associated with differences in diet, sensory perception, appetite and enjoyment of eating?-An explorative study

BACKGROUND

Orofacial function is believed to influence an individual's diet. knowledge on appetite and enjoyment of eating in orofacially impaired individuals is scarce.

OBJECTIVE

We aimed to explore potential associations between impaired orofacial function, that is, orofacial pain, jaw function limitation and xerostomia, respectively, and diet, appetite, taste perception, as well as the enjoyment of eating.

METHODS

An online questionnaire was shared among Aarhus University's dental patients and through social media. A convenience sample of 351 individuals responded (97 men, 254 women, aged 18-86 years). Participants were divided into groups with and without orofacial pain or xerostomia based on responses. Questions about food intake, appetite, meal-related well-being and oral/general health were included. Data were analysed using Mann Whitney U tests, Spearman's correlation, Chi-square tests, and t-tests.

RESULTS

Participants with (n = 123) and without (n = 228) orofacial pain differed significantly regarding age, perceived oral/general health, frequency of consumption of for example cooked vegetables and raw whole fruit, perception of sourness, chewiness, and nausea/pain when eating (p ≤ .031). Participants with (n = 101) and without (n = 250) xerostomia differed significantly regarding perceived oral/general health, intake of prepared fruit, alcohol, ice cream/mousse/pudding, general appetite, intake of breakfast and liquid snacks, nausea/pain when eating, taste and chewiness of food (p ≤ .038).

CONCLUSION

Diet, appetite, taste and sensory perception, as well as enjoyment of eating of individuals reporting orofacial pain and/or xerostomia differed slightly to that of individuals free of such symptoms. However, due to the explorative nature of this study, the results should be interpreted with caution pending further research on potential long-term effects on nutritional status and well-being.

Mechanical overload induces TMJ disc degeneration via TRPV4 activation

OBJECTIVE

The temporomandibular joint (TMJ) disc cushions intraarticular stress during mandibular movements. While mechanical overloading is related to cartilage degeneration, the pathogenesis of TMJ disc degeneration is unclear. Here, we determined the regulatory role of mechanoinductive transient receptor potential vanilloid 4 (TRPV4) in mechanical overload-induced TMJ disc degeneration.

METHODS

We explored the effect of mechanical overload on the TMJ discs in a rat occlusal interference model in vivo, and by applying sustained compressive force in vitro. TRPV4 inhibition was delivered by small interfering RNA or GSK2193874; TRPV4 activation was delivered by GSK1016790A. The protective effect of TRPV4 inhibition was validated in the rat occlusal interference model.

RESULTS

Occlusal interference induced TMJ disc degeneration with enhanced extracellular matrix degradation in vivo and mechanical overload promoted inflammatory responses in the TMJ disc cells via Ca2+ influx with significantly upregulated TRPV4. TRPV4 inhibition reversed mechanical overload-induced inflammatory responses; TRPV4 activation simulated mechanical overload-induced inflammatory responses. Moreover, TRPV4 inhibition alleviated TMJ disc degeneration in the rat occlusal interference model.

CONCLUSION

Our findings suggest TRPV4 plays a pivotal role in the pathogenesis of mechanical overload-induced TMJ disc degeneration and may be a promising target for the treatment of degenerative changes of the TMJ disc.

Temporomandibular disorder patients with excessive daytime sleepiness present greater pain intensity and reduced jaw function

BACKGROUND

Sleep disorders are associated with temporomandibular disorders (TMDs). Limited studies have focused on excessive daytime sleepiness (EDS) and its impact on jaw functions in TMD patients.

OBJECTIVE

The aim of the present investigation was to identify the impact of EDS on pain and jaw function in TMD patients.

METHODS

A total of 338 TMD patients (50 males and 288 females) was included. The Epworth Sleepiness Scale (ESS) was used to classify patients into EDS group (score ≥ 10) and non-EDS group (score < 10). The Jaw Functional Limitation Scale 8-item (JFLS-8) was used to assess the severity of jaw dysfunction. Pain intensity was evaluated using the Visual Analogue Scale (VAS). Anxiety and depression were evaluated using the Generalised Anxiety Disorder 7-item (GAD-7) and the Patient Health Questionnaire 9-item (PHQ-9). All included patients were diagnosed with pain-related TMD (PT), intra-articular TMD (IT) or combined TMD (CT).

RESULTS

Compared with non-EDS patients, EDS patients exhibited more severe jaw dysfunction, greater pain intensity and higher PHQ-9 scores (p < .05). Multivariate analyses showed that EDS (B = 3.69), female gender (B = 3.69), and elevated GAD-7 score (B = 0.73) were significantly associated with an increased score on the JFLS-8 (p < .05). Moreover, bivariate logistic regression analysis indicated a significant relationship between EDS and PT (OR = 2.70, p = .007).

CONCLUSION

The presence of EDS was more closely related to PT, but the causal relationship between them needs to be further confirmed. More concern and intervention to alleviate poor sleep quality might be highlighted during the treatment of TMD, especially PT subtype.

Pain mechanisms in the transgender individual: a review

Specific Aim

Provide an overview of the literature addressing major areas pertinent to pain in transgender persons and to identify areas of primary relevance for future research.

Methods

A team of scholars that have previously published on different areas of related research met periodically though zoom conferencing between April 2021 and February 2023 to discuss relevant literature with the goal of providing an overview on the incidence, phenotype, and mechanisms of pain in transgender patients. Review sections were written after gathering information from systematic literature searches of published or publicly available electronic literature to be compiled for publication as part of a topical series on gender and pain in the Frontiers in Pain Research.

Results

While transgender individuals represent a significant and increasingly visible component of the population, many researchers and clinicians are not well informed about the diversity in gender identity, physiology, hormonal status, and gender-affirming medical procedures utilized by transgender and other gender diverse patients. Transgender and cisgender people present with many of the same medical concerns, but research and treatment of these medical needs must reflect an appreciation of how differences in sex, gender, gender-affirming medical procedures, and minoritized status impact pain.

Conclusions

While significant advances have occurred in our appreciation of pain, the review indicates the need to support more targeted research on treatment and prevention of pain in transgender individuals. This is particularly relevant both for gender-affirming medical interventions and related medical care. Of particular importance is the need for large long-term follow-up studies to ascertain best practices for such procedures. A multi-disciplinary approach with personalized interventions is of particular importance to move forward.

Associations of inflammatory polyarthritis with clinical and radiological findings of temporomandibular disorders

OBJECTIVE

To evaluate the association of different forms of inflammatory polyarthritis with clinical signs of temporomandibular disorders (TMD) and radiological findings in temporomandibular joint (TMJ), based on a nationwide health survey in Finland. The aim was also to assess the presence of clinical and radiological TMD findings in subjects with increased risk for developing rheumatoid arthritis (RA).

MATERIAL AND METHODS

Anationally representative sample included 6331 Finnish adults who participated in the Health 2000 Survey (BRIF8901). Subjects were examined for signs of TMD, findings in panoramic radiograph of TMJ, musculoskeletal health and serology (rheumatoid factor, RF, and anti-cyclic citrullinated peptide, aCCP).

RESULTS

Sixty-four percent of seronegative RAand 60% of seropositive RAsubjects had at least one sign of TMD. While adjusting for confounding factors (gender, age, dentures and smoking history), RAwas significantly associated with crepitation and abnormal radiological findings in TMJ. Seronegative RAwas also associated with restricted mouth opening. Systemic autoimmunity associated with RA("at risk of RA") was not associated with clinical or radiological TMD findings.

CONCLUSIONS

Clinical and radiological findings of TMD are more prevalent among subjects with inflammatory polyarthritis than among the population in general in the Finnish adult population.

Impact of professional, recreational and nonsinging on temporomandibular disorders - a comparative study based on a self-assessment questionnaire

BACKGROUND

This study investigates the relationship between professional and recreational singing on temporomandibular disorders (TMDs) in women compared to a nonsinging control group.

METHODS

A total of 288 female subjects between the ages of 18 and 45 participated in the self-assessment questionnaire including demographic data, as well as questions on vocal practice and TMDs symptoms. Depending on the singing time per week, the (non)vocalists were assigned to the groups professional (n = 96), recreational (n = 96) and nonsingers (n = 96).

RESULTS

The TMDs prevalence in professional singers (42%) was higher than that in recreational singers (31%) and noticeably higher than that in nonsingers (25%). The Fisher-Freeman-Halton exact test showed that the differences between the groups were not noticeable (p = .053) but could be formulated as tendencies. The professionals suffered much more from restricted jaw movement (p = .004; OR = 2.718; 95% CI = 1.409-5.242), temporomandibular joint sounds (p < .009; OR = 2.267; 95% CI = 1.264-4.064) and temporomandibular pain (p = .010; OR = 2.333; 95% CI = 1.264-4.308) than nonsingers.

CONCLUSIONS

Singing might have an enhancing effect on the appearance of TMDs. In particular, professional singers suffered more from self-reported TMDs than recreational singers and nonsingers. In addition to the high level of physical workload if participating in professional singing, the psychosocial impact should be investigated more in further studies. No new treatment strategies resulted from this study, as the etiological significance of singing is still unclear. Knowledge about risk factors for multifactorial TMDs can help practitioners and patients prevent and treat TMDs.

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

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.

Obstructive sleep apnea treatment improves temporomandibular disorder pain

PURPOSE

The existence of a bidirectional relationship between poor sleep and pain intensity has been studied, and good sleep quality has been found to be a key factor underlying pain control. The purpose of this prospective cohort study was to observe if OSA treatment provides a reduction in temporo-mandibular disorder (TMD) pain and headache attributed to TMD in patients with obstructive sleep apnea (OSA) after 18 months of OSA treatment.

METHODS

A prospective cohort study was conducted on consecutive patients suffering from OSA. Patients underwent polysomnography and TMD examination according to the DC/TMD protocol at baseline and after 18 months. Intensity of TMD pain and headache attributed to TMD were analyzed.

RESULTS

Of 40 patients (31 men, mean age 51.3 ± 10.3 years), 33 underwent OSA treatment. At the follow-up examination after 18 months, significant improvements in the intensity of pain-related TMD and headache attributed to TMD were observed (p < 0.05). Seven patients did not start treatment for OSA or discontinued treatment. These patients did not show any significant difference in intensity of TMD-pain or headache attributed to TMD after 18 months (p > 0.05).

CONCLUSIONS

Significant reductions in intensity of pain-related TMD and headache attributed to TMD were observed in patients with OSA after 18 months of OSA treatment onset, while no difference was observed in subjects not undergoing or discontinuing OSA treatment.

TRIAL REGISTRATION

The protocol was registered on ClinicalTrials.gov database with number NCT04948541.

Changes in oral health-related quality of life after self-care treatment in patients with myofascial pain

OBJECTIVE

The aim of this study was to evaluate the changes in oral health-related quality of life (OHRQoL) of patients with myofascial pain treated by means of self-care measures.

METHODS

Fifteen patients with myofascial pain had OHRQoL evaluated by the Oral Health Impact Profile (OHIP-TMD) questionnaire and were instructed for self-care measures verbally and with a printed guide in the first consultation (T0), after 30 days (T1) and 60 days (T2). Paired t-test was performed to evaluate changes through time.

RESULTS

OHIP-TMD scores were 29.3 (SD 10.2) at T0, 18.9 (SD 11.2) at T1, and 15.9 (SD 10.7) at T2. There was a reduction of scores related to the OHIP-TMD domains of functional limitation, physical pain, psychological and social inability and incapacity (T1 and T2), and psychological discomfort (T2).

CONCLUSION

Self-care measures had positive effects on the myofascial pain treatment, reducing physical pain generated by TMD and improving patients' OHRQoL.

Severity and form of temporomandibular disorder symptoms: Functional, physical, and psychosocial impacts

OBJECTIVE

The associations between the presence of differing severity/form of temporomandibular disorder (TMD) symptoms and oral health-related quality of life (OHRQoL) were explored.

METHODS

The severity and form of TMDs in young adults were categorized based on the Fonseca Anamnestic Index (FAI) and Diagnostic Criteria for TMDs (DC/TMD), and OHRQoL was assessed with the Oral Health Impact Profile-14 (OHIP-14). Data were analyzed using non-parametric statistics (α = 0.05).

RESULTS

The study cohort consisted of 501 young adults (mean age 19.7 ± 1.3 years; 75.2% women). Participants with severe/moderate TMDs had significantly higher OHIP severity scores than those with mild/no TMDs. Moreover, participants with combined/pain-related symptoms exhibited significantly higher severity scores compared to those without symptoms. The physical pain and psychological discomfort domains were typically more impaired regardless of severity/form of TMD symptoms.

CONCLUSION

More severe and painful symptoms were related to greater impairments in OHRQoL, especially in the physical and psychological domains.

Age distribution of East Asian TMD patients and age-related differences in DC/TMD axis I findings

OBJECTIVES

The pattern of age distribution in East Asian temporomandibular disorder (TMD) patients and age-related differences in DC/TMD diagnostic subtypes/categories were evaluated.

SUBJECTS AND METHODS

TMD patients from two University-based centers in China and South Korea were enrolled. Axis I physical diagnoses were rendered according to DC/TMD. Patients were categorized into six age groups (15-24, 25-34, 35-44, 45-54, 55-64, and 65-84 years; Groups A-F respectively).

RESULTS

Youths/young adults (Groups A-C) formed 74.1% of TMD patients. TMJ disc displacements (74.9%), arthralgia (49.2%), and degenerative joint disease [DJD] (36.8%) were the most common TMD subtypes. The majority had combined (54.0%) and chronic (58.5%) TMDs. Youths/young adults and middle-aged/old adults had substantially lower frequencies of merely pain-related (6.2-14.5%) and intra-articular (13.8-16.8%) TMDs correspondingly. "Being female" increased the prospects of pain-related/combined TMDs by 96%/49%, respectively.

CONCLUSIONS

East Asian TMD patients comprised mostly of youths/young adults who had an alarmingly high prevalence of TMJ DJD.

A Preliminary Diagnostic Model for Forward Head Posture among Adolescents Using Forward Neck Tilt Angle and Radiographic Sagittal Alignment Parameters

Despite numerous attempts to correct forward head posture (FHP), definitive evidence-based screening and diagnostic methods remain elusive. This study proposes a preliminary diagnostic methodology for FHP, utilizing a noninvasive body angle measurement system as a screening test for FHP and incorporating radiological parameters for sagittal alignment. We enrolled 145 adolescents for FHP screening. The forward neck tilt angle (FNTA), defined as the angle between the vertical line and the line connecting the participant's acromion and tragus, was measured using the POM-Checker (a noninvasive depth sensor-based body angle measurement system). A whole-spine standing lateral radiograph was obtained, and eight sagittal alignment parameters were measured. Statistical analyses of the association between the FNTA and eight sagittal alignment parameters were conducted. We used 70% of the participant data to establish a preliminary diagnostic model for FHP based on FNTA and each sagittal alignment parameter. The accuracy of the model was evaluated using the remaining 30% of the participant data. All radiological parameters of sagittal alignment showed weak statistical significance with respect to FNTA (best case: r = 0.16, p = 0.0500; cranial tilt). The proposed preliminary diagnostic model for FHP demonstrated 95.35% agreement. Notably, the model using FNTA without radiological parameters accurately identified (100%) participants who required radiographic scanning for FHP diagnosis. Owing to the weak statistical significance of the association between radiological parameters and external body angle, both factors must be considered for accurate FHP diagnosis. When a clear and severe angle variation is observed in an external body angle check, medical professionals should perform radiographic scanning for an accurate FHP diagnosis. In conclusion, FNTA assessment of FNTA through the proposed preliminary diagnostic model is a significant screening factor for selecting participants who must undergo radiographic scanning so that a diagnosis of FHP can be obtained.

Sociodemographic Profile: A Forgotten Factor in Temporomandibular Disorders? A Scoping Review

The literature on Temporomandibular Disorders (TMD) incidence commonly reports sociodemographic factors such as gender and age. However, the role and prevalence of other sociodemographic factors in TMD are not well defined. Therefore, this scoping review aimed to report the prevalence of sociodemographic factors in TMD patients. A systematic search was conducted in the PubMed and Web of Science databases to identify clinical trials in adult populations, using the Research Diagnostic Criteria for TMD (RDC/TMD) or the Diagnostic Criteria for TMD (DC/TMD) and reporting sociodemographic data in TMD patients. Twenty-seven studies meeting the criteria were included in this review. The most commonly reported sociodemographic factors assessed in the included studies were age, race, education, job, income, and marital status. TMD prevalence was observed to be higher among younger and divorced individuals among the included studies. However, conflicting results were found for education level, and employment was not considered a risk factor for TMD. Although this review has methodological limitations, it suggests an association between TMD incidence and certain sociodemographic factors; nevertheless, further studies are needed to establish this relationship more conclusively.

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

OBJECTIVES

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.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Correlation between temporomandibular joints and craniocervical posture in patients with bilateral anterial disc displacement

OBJECTIVE

To study the changes of temporomandibular joints and craniocervical posture in adult patients with bilateral anterior disc displacement, and to explore their correlation, which may provide some clinical value for clinical diagnosis and treatment planning.

METHODS

Ninety-eight adult patients were divided into 3 groups: 29 patients in bilateral disc normal position group (BN), 33 patients in bilateral Anterior Disc Displacement With Reduction group (ADDWR) and 36 patients in bilateral Anterior Disc Displacement Without Reduction group (ADDWoR). Dolphin and Uceph software were used to measure 14 items of temporomandibular joint and 11 items of craniocervical posture for comparison and correlation analysis between groups.

RESULTS

There were significant differences in bilateral joint space between three groups. Compared with the BN, the anteroposterior diameter of the condyle was significantly reduced, the condyle was significantly displaced posteriorly and superiorly in the ADDWR and ADDWoR, but the joint fossa width and joint fossa depth did not change significantly. Cervical curvature and inclination were greater in patients with anterior disc displacement than BN, indicating that the craniocervical posture of adult patients with anterior disc displacement was extended and protrusive.

CONCLUSION

Anterior disc displacement of the temporomandibular joint can displace the condyle upwards and posteriorly and reduce the anteroposterior diameter of condyle, and then make the condyle closer to the wall of articular fossa to induce joint symptoms. Additionally, craniocervical postural position is significantly affected, which may be related to compensate for the effects of airway space.

The effects of dry needling and face yoga on pain, depression, function, and sleep quality in patients with temporomandibular dysfunction

CONTEXT

Temporomandibular joint dysfunction (TMD) poses significant challenges due to its diverse symptoms and impact on patients' daily lives.

OBJECTIVE

This study aimed to explore the effectiveness of two innovative interventions, dry needling and face yoga, in managing TMD-related issues such as pain, depression, and sleep quality.

DESIGN AND STUDY PARTICIPANTS

Ninety patients with TMD symptoms were enrolled in a prospective randomized controlled trial. The patients were divided into three groups: dry needling, face yoga, and a control group. Various assessments, including Visual Analog Scale for pain, Beck Depression Inventory for depression, and Pittsburgh Sleep Quality Index for sleep quality, were conducted before and 6 weeks after the interventions.

RESULTS

A decrease in pain levels and a statistically significant increase in jaw joint movements (mouth opening, protrusive movement, lateral movements) were observed in the dry needling and face yoga groups after treatment (p <0.05). Additionally, improvements in sleep quality were observed (p <0.05).

CONCLUSION

Dry needling and face yoga interventions demonstrated efficacy in managing TMD symptoms, including pain relief and improved jaw movement. The findings suggest that these interventions can be valuable additions to the treatment regimen for patients suffering from TMD-related issues. However, further research is warranted to explore the long-term effects and mechanisms underlying these interventions in TMD management.

Forced mouth opening induces post-traumatic hyperalgesia and associated peripheral sensitization after temporomandibular joints injury in mice

Temporomandibular disorder (TMD) is the most prevalent painful condition in the craniofacial area. The pathophysiology of TMD is not fully understood, and it is necessary to understand pathophysiology underlying painful TMD conditions to develop more effective treatment methods. Recent studies suggested that external or intrinsic trauma to TMJ is associated with chronic TMD in patients. Here, we investigated the effects of the TMJ trauma through forced-mouth opening (FMO) in mice to determine pain behaviors and peripheral sensitization of trigeminal nociceptors. FMO increased mechanical hyperalgesia assessed by von Frey test, spontaneous pain-like behaviors assessed by mouse grimace scale, and anxiety-like behaviors assessed by open-field test. In vivo GCaMP Ca 2+ imaging of intact trigeminal ganglia (TG) showed increased spontaneous Ca 2+ activity and mechanical hypersensitivity of TG neurons in the FMO compared to the sham group. Ca 2+ responses evoked by cold, heat, and capsaicin stimuli were also increased. FMO-induced hyperalgesia and neuronal hyperactivities were not sex dependent. TG neurons sensitized following FMO were primarily small to medium-sized nociceptive afferents. Consistently, most TMJ afferents in the TG were small-sized peptidergic neurons expressing calcitonin gene-related peptides, whereas nonpeptidergic TMJ afferents were relatively low. FMO-induced intraneural inflammation in the surrounding tissues of the TMJ indicates potentially novel mechanisms of peripheral sensitization following TMJ injury. These results suggest that the TMJ injury leads to persistent post-traumatic hyperalgesia associated with peripheral sensitization of trigeminal nociceptors.

Filling in the Gaps. Making Sense of Living with Temporomandibular Disorders: A Reflexive Thematic Analysis

INTRODUCTION

Persistent, painful temporomandibular disorders (TMDs) are challenging to manage and usually require the active engagement of patients. To achieve this, it is necessary to understand the complex and multifactorial nature of persistent pain. Many dental professionals have little education about persistent pain and may prefer to offer structural management and advice. This research aims to explore how people understand their persistent TMD and how this understanding has been influenced by their treatment providers.

METHODS

Twenty-one people were recruited to represent a diversity of experience with persistent TMD. Interviews followed a semistructured topic guide. Themes were constructed through reflexive thematic analysis to represent how people made sense of their symptoms and the messages that they had picked up through their treatment journey.

RESULTS

Participants described examples of conflicting opinions and inconsistent management recommendations. They rarely recalled collaborative discussions about the nature and complexity of their symptoms and different options for treatment. This experience is represented by a single theme, "a medical merry-go-round." Subthemes of "a medical journey to nowhere-participants' frustrated attempts to find medical management that will end their pain" and "is it me?-participants' questioning their role in persisting pain" kept participants on the merry-go-round, while symptom resolution and participants' emerging development of a holistic understanding of their TMD pain provided exit points. Understanding pain holistically tended to be helpful and typically occurred despite rather than because of the advice given in routine treatment settings.

CONCLUSION

Participants in this study had not typically found their pain management within dental and medical settings to have helped them to construct meaning and understand their experiences of painful TMD. However, understanding symptoms holistically was experienced as beneficial. This study suggests that improved communication and signposting within services for persistent TMD may be beneficial to patients with TMD pain.

KNOWLEDGE TRANSFER STATEMENT

Results of this study confirm that being offered a series of anatomically based, singular-cause explanations for persisting pain symptoms had been experienced as unhelpful by the participants who had sought help for their TMD. Participants highlighted the importance of accurate and collaborative communication and of dental professionals explicitly adopting and communicating a biopsychosocial understanding of pain to their patients who have TMD. Results highlight that some people can struggle to manage persisting pain with minimal support. Signposting patients to appropriate services and resources may help them to understand more about the nature of persistent pain and methods of managing it.

Pain-sensorimotor interactions: New perspectives and a new model

How pain and sensorimotor behavior interact has been the subject of research and debate for many decades. This article reviews theories bearing on pain-sensorimotor interactions and considers their strengths and limitations in the light of findings from experimental and clinical studies of pain-sensorimotor interactions in the spinal and craniofacial sensorimotor systems. A strength of recent theories is that they have incorporated concepts and features missing from earlier theories to account for the role of the sensory-discriminative, motivational-affective, and cognitive-evaluative dimensions of pain in pain-sensorimotor interactions. Findings acquired since the formulation of these recent theories indicate that additional features need to be considered to provide a more comprehensive conceptualization of pain-sensorimotor interactions. These features include biopsychosocial influences that range from biological factors such as genetics and epigenetics to psychological factors and social factors encompassing environmental and cultural influences. Also needing consideration is a mechanistic framework that includes other biological factors reflecting nociceptive processes and glioplastic and neuroplastic changes in sensorimotor and related brain and spinal cord circuits in acute or chronic pain conditions. The literature reviewed and the limitations of previous theories bearing on pain-sensorimotor interactions have led us to provide new perspectives on these interactions, and this has prompted our development of a new concept, the Theory of Pain-Sensorimotor Interactions (TOPSMI) that we suggest gives a more comprehensive framework to consider the interactions and their complexity. This theory states that pain is associated with plastic changes in the central nervous system (CNS) that lead to an activation pattern of motor units that contributes to the individual's adaptive sensorimotor behavior. This activation pattern takes account of the biological, psychological, and social influences on the musculoskeletal tissues involved in sensorimotor behavior and on the plastic changes and the experience of pain in that individual. The pattern is normally optimized in terms of biomechanical advantage and metabolic cost related to the features of the individual's musculoskeletal tissues and aims to minimize pain and any associated sensorimotor changes, and thereby maintain homeostasis. However, adverse biopsychosocial factors and their interactions may result in plastic CNS changes leading to less optimal, even maladaptive, sensorimotor changes producing motor unit activation patterns associated with the development of further pain. This more comprehensive theory points towards customized treatment strategies, in line with the management approaches to pain proposed in the biopsychosocial model of pain.

TET1-mediated epigenetic regulation of tumor necrosis factor-α in trigeminal ganglia contributes to chronic temporomandibular joint pain

Chronic temporomandibular joint (TMJ) pain profoundly affects patients' quality of life. Trigeminal tumor necrosis factor-α (TNFα) plays a pivotal role in mediating TMJ pain in mice, yet the underlying epigenetic mechanisms remain enigmatic. To unravel these epigenetic intricacies, we employed a multifaceted approach. Hydroxymethylated DNA immunoprecipitation (hMeDIP) and chromatin immunoprecipitation (ChIP) followed by qPCR were employed to investigate the demethylation of TNFα gene (Tnfa) and its regulation by ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in a chronic TMJ pain mouse model. The global levels of 5-hydroxymethylcytosine (5hmc) and percentage of 5hmc at the Tnfa promoter region were measured in the trigeminal ganglia (TG) and spinal trigeminal nucleus caudalis (Sp5C) following complete Freund's adjuvant (CFA) or saline treatment. TET1 knockdown and pain behavioral testing were conducted to ascertain the role of TET1-mediated epigenetic regulation of TNFα in the pathogenesis of chronic TMJ pain. Our finding revealed an increase in 5hmc at the Tnfa promoter region in both TG and Sp5C of CFA-treated mice. TET1 was upregulated in the mouse TG, and the ChIP result showed TET1 direct binding to the Tnfa promoter, with higher efficiency in the CFA-treated group. Immunofluorescence revealed the predominant expression of TET1 in trigeminal neurons. TET1 knockdown in the TG significantly reversed CFA-induced TNFα upregulation and alleviated chronic TMJ pain. In conclusion, our study implicates TET1 as a vital epigenetic regulator contributing to chronic inflammatory TMJ pain via trigeminal TNFα signaling. Targeting TET1 holds promise for epigenetic interventions in TMJ pain management.

Does childhood maltreatment play a role in temporomandibular disorders?

The aim of this study was to find out if experiences of maltreatment in childhood have an effect on the occurrence of temporomandibular joint disorders (TMD). The study was conducted on 380 volunteer adults (252 females and 128 males), with a mean (SD) age of 27.63 (9.06) years. The level of TMD was assessed using the Fonseca Anamnestic Index (FAI). Childhood Trauma Questionnaires (CTQ) were completed by the participants and their marital status and educational level were recorded. FAI scores were significantly higher in females than in males. There was no statistically significant difference between gender and total CTQ score. Moreover, there was no statistically significant difference between educational status, marital status, and total CTQ score. FAI scores correlated positively with total CTQ scores in all individuals. Similarly FAI scores correlated positively with total CTQ scores in males and females. Childhood maltreatment is associated with TMDs. Dentists should be aware that possible collaboration with psychiatrists and/or psychologists when treating patients with TMD could increase the success of their treatment.

Occurrence of Temporomandibular Disorders among patients undergoing treatment for Obstructive Sleep Apnoea Syndrome (OSAS) using Mandibular Advancement Device (MAD): A Systematic Review conducted according to PRISMA guidelines and the Cochrane handbook for systematic reviews of interventions

BACKGROUND

Patients undergoing mandibular advancement device (MAD) therapy for obstructive sleep apnea (OSA) may experience changes in jaw position and altered occlusion. This could potentially contribute to the development or exacerbation of TMD symptoms. The literature on the long-term impact of MAD treated for OSA on TMD is scarce. Hence, this review was undertaken to ascertain the occurrence of TMD in MAD users.

METHODS

A comprehensive search protocol was implemented across several online databases using MeSH keywords and Boolean operators. A standardised data extraction form was developed specifically for this review. Two reviewers independently extracted the data. RoB-2 was used to evaluate the methodological quality of the included studies.

RESULTS

A total of 13 clinical studies were selected for this review. Some studies reported a significant reduction in the severity and frequency of TMD symptoms following MAD treatment. However, other studies did not observe significant changes in TMD symptoms or TMJ-related parameters from baseline to follow-up intervals. Temporary increases in TMJ-related pain or symptoms at the beginning of the follow-up period, which later subsided, were reported in some studies. Overall, MAD was not discontinued in any OSA patient due to TMDs.

CONCLUSION

The findings reveal that different outcomes associated with TMD are affected differently by MAD treatment for OSAS. According to a few studies, MAD therapy significantly reduced the severity and frequency of TMD symptoms. Other research, however, found no appreciable modifications in TMD symptoms or TMJ-related indicators. Although the overall results point to no significant effect of MAD treatment on TMD symptoms, the disparity in results between studies highlights the need for additional studies using standardised approaches.

Psychological characteristics of young adults with temporomandibular disorders, somatization and combined conditions: A multidimensional evaluation

BACKGROUND

Temporomandibular disorders and somatization have shown interrelation in many studies. The physical and psychological factors which contributed to the occurrence and relation of both conditions are yet to be determined.

OBJECTIVES

The personality traits, coping styles and psychological distress of young adults with temporomandibular disorder (TMD) and somatic symptoms were characterized together with the determination of psychological risk factors for TMDs, somatization and combined conditions.

METHODS

Participants were recruited from university-attending young adults. TMD and somatic symptoms were appraised with the short-form Fonseca Anamnestic Index and Patient Health Questionnaire-15. Psychological variables were assessed with the Big Five Personality Inventory-10, Brief-COPE Inventory and Depression, Anxiety, and Stress Scales-21. Data were evaluated using chi-squared/non-parametric tests and logistic regression analyses (α = .05).

RESULTS

Among the 507 participants (mean age 22.2 ± 1.5 years), 46.4% reported no TMD/somatic symptoms (NS) while 7.5%, 34.5% and 11.6% had TMDs only (TS), somatization only (SS) and combined TMDs-somatization (CS), respectively. Significant differences in conscientiousness (NS > SS), agreeableness (NS, TS > CS; NS > SS), dysfunctional coping, general distress, depression, anxiety and stress (CS ≥ SS > NS) were discerned. Multivariate analyses indicated that the odds of TS were increased by anxiety (OR = 1.10; 95% CI = 1.01-1.21), while the odds of SS/CS were affected by anxiety (OR = 1.15; 95% CI = 1.06-1.25/OR = 1.34; 95% CI = 0.19-1.52) and problem-focused coping (OR = 0.71; 95% CI = 0.56-0.89/OR = 0.55; 95% CI = 0.39-0.78).

CONCLUSION

Though individuals with TMDs and somatization have dissimilar psychological profiles, anxiety constantly increased their likelihood. Problem-focused coping strategies may help alleviate psychosocial and physical stressors associated with TMDs and somatization.

Prevalence of temporomandibular disorders in the Brazilian population: A systematic review and meta-analysis

This systematic review aimed to assess the prevalence of temporomandibular disorders (TMD) in the Brazilian population, with studies that used the RDC/TMD or DC/TMD as diagnostic tools. A total of 6365 people from 11 studies were included. Sample mean age ranged from 12 to 69.5 years. The pooled prevalence of TMD was 33.6% (95% CI 31.5-35.8; I2 = 37.2). Prevalence of TMD was higher in females (37.0%) than in males (29.3%). Our results indicate that TMD is a prevalent condition across Brazil's territories. The results from this meta-analysis can help calculate more accurate sample sizes for future studies.

Gender differences in lateral pterygoid muscle in patients with anterior disk displacement

OBJECTIVE

To use quantitative MRI to assess gender differences in lateral pterygoid muscle (LPM) characteristics in patients with anterior disk displacement (ADD).

METHODS

Lateral pterygoid muscle of 51 patients diagnosed with temporomandibular joint disorders (TMD) who underwent T1-weighted Dixon and T1-mapping sequences were retrospectively analyzed. There were 34 female patients (10 with bilateral normal position disk [NP]; 24 with bilateral ADD) and 17 male patients (eight with bilateral NP; nine with bilateral ADD) among them. After controlling for age, differences in fat fraction, T1 value, volume and histogram features related to gender and disk status were tested with 2-way ANCOVA or Quade ANCOVA with Bonferroni correction.

RESULTS

Volume of LPM in NP was significantly smaller than that of ADD (p < 0.001). Fat fraction of LPM in females with NP was significantly higher than males with NP (p < 0.05). Females with ADD showed a significantly higher T1 value (p < 0.05), and higher intramuscular heterogeneity than males with ADD.

CONCLUSIONS

Lateral pterygoid muscle in female TMD patients presented more fatty infiltration in the NP stage and might present more fibrosis in the ADD stage compared with males. Together, this leads to more serious intramuscular heterogeneity during the pathogenesis of ADD in females.