Characteristics of painful temporomandibular disorders and their influence on jaw functional limitation and oral health-related quality of life.

BACKGROUND: There is limited knowledge about the impact of painful temporomandibular disorders (TMDs) and pain characteristics on jaw functional limitation and oral health-related quality of life (OHRQoL) in TMD patients. OBJECTIVES: The influence of painful TMDs and pain characteristics on jaw functional limitation and OHRQoL was investigated. Inter-relationships between limitation in jaw function and various OHRQoL domains, along with facial pain attributes predicting impaired jaw function and diminished OHRQoL were also examined. METHODS: TMD patients were recruited from a university-based hospital. A comprehensive questionnaire comprising demographic variables, the DC/TMD Symptom Questionnaire, Graded Chronic Pain Scale, Jaw Functional Limitation Scale-8 (JFLS-8) and Oral Health Impact Profile-TMD (OHIP-TMD) was administered. Participants underwent a protocolized physical examination, and TMD diagnoses were determined utilising the DC/TMD algorithms. Participants were subsequently stratified into intra-articular/pain-related/combined TMD groups, as well as no TMD pain, acute/chronic pain and low/high-intensity pain groups. Data were assessed using non-parametric and hierarchical linear regression analyses (α = .05). RESULTS: The final sample consisted of 280 participants (mean age 31.2 (SD 11.8) years; 79.3% women). Significant differences in pain characteristics, JFLS-8, and global OHIP scores were observed across the various TMD subtypes, pain chronicity and pain intensity categories. Pain intensity and pain-related interference exhibited moderate correlations with JFLS-8 and global OHIP scores (rs = 0.53-0.60). Moderate associations were also noted between JFLS-8 and global OHIP, as well as most OHIP domains (rs = 0.42-0.64). Both jaw functional limitation and OHRQoL were predicted by sex, pain intensity and pain-related interference. CONCLUSIONS: Sex, pain intensity and pain-related interference are key determinants for both impaired jaw function and diminished OHRQoL, with pain-related interference exerting a more pronounced effect.

Rasch validation of the oral health impact profile for temporomandibular disorders.

OBJECTIVES: This study examined the metric properties of the Oral Health Impact Profile for Temporomandibular Disorders (OHIP-TMD) using Factor/Rasch analyses and created a short-form version of the measure. SUBJECTS AND METHODS: Aggregated OHIP-TMD data were obtained from a cross-sectional study involving 844 TMD patients with diagnostic criteria for TMDs defined conditions. The dimensionality of the OHIP-TMD was first evaluated with exploratory factor analysis. An eigenvalue >1.0 and oblique oblimin rotation were applied for extracting the factors. Rasch analysis was subsequently performed on the primary dimension using the ConQuest software. RESULTS: Multi-dimensionality of the OHIP-TMD was observed with the primary dimension comprising ten items. Adequate fit to the Rasch model was noted after deleting item 8 with infit/outfit mean-square values ranging from 0.75 to 1.40 logits. Item difficulty ranged from -0.75 to 1.05 logits, while participants' ability to respond varied from -4.55 to 5.19 logits. The respondent spread was slightly skewed and satisfactory item-response targeting was present. CONCLUSIONS: The 22-item OHIP-TMD demonstrated multi-dimensionality with the primary dimension consisting of nine reliable items with adequate fit to the Rasch model. The 9-item short-form version of the OHIP-TMD (SOHIP-TMD) is a promising tool for evaluating OHRQoL.

TMJ degenerative joint disease: relationships between CBCT findings, clinical symptoms, and signs.

OBJECTIVES: The relationships between cone-beam computed tomography (CBCT) findings, Temporomandibular disorder (TMD) symptoms, and signs were investigated in patients with TMJ degenerative joint disease (DJD). MATERIAL AND METHODS: Adult patients with Diagnostic Criteria for TMDs (DC/TMD)-defined intra-articular conditions were enrolled and subjected to CBCT assessment. The participants were organized into three groups, namely no (NT), early (ET), and late (LT) TMJ DJD based on radiographic findings. TMD symptoms/signs were appraised using the DC/TMD methodology. Statistical analyses were performed using Chi-square/non-parametric tests and Kappa statistics (α = 0.05). RESULTS: The mean age of the participants (n = 877) was 30.60 ± 11.50 years (86.6% women). NT, ET, and LT were observed in 39.7%, 17.0%, and 43.3% of the study sample. Significant differences in the prevalence of TMD symptoms (TMD pain, TMJ sounds, opening, and closing difficulty) and signs (TMD/TMJ pain, TMJ clicking/crepitus, and opening limitation) were discerned among the three groups (p ≤ .001). TMD/TMJ pain and opening difficulty/limitation were more prevalent in early rather than late degenerative changes. While moderate agreements between symptoms and signs were observed for TMD pain/opening limitation, the concurrence for TMJ sounds was fair. CONCLUSIONS: Young adults with TMJ sounds and pain should be examined with CBCT to establish the extent/progress of osseous changes.

Comparison of painful temporomandibular disorders, psychological characteristics, sleep quality, and oral health-related quality of life of patients seeking care before and during the Covid-19 pandemic.

BACKGROUND: Literature concerning Temporomandibular disorders (TMDs) and the Covid-19 pandemic is limited and disparate findings related to TMD frequencies, psychological distress, and quality of life were presented. This study investigated the prevalence of painful Temporomandibular disorders (TMDs) and compared the psychological, sleep, and oral health-related quality of life profiles of patients seeking TMD care before and during the Covid-19 pandemic. METHODS: Data were accrued from consecutive adult patients 12 months before (BC; control) and during (DC; case group) the Covid-19 pandemic. The Diagnostic Criteria for TMDs (DC/TMD), Depression, Anxiety, Stress Scales (DASS)-21, Pittsburgh Sleep Quality Index (PSQI), and Oral Health Impact Profile (OHIP)-TMDs were utilized and statistical analysis was performed using Chi-square/non-parametric tests (α = 0.05). RESULTS: The prevalence of painful TMDs was 50.8% before and 46.3% during the pandemic. Significant differences in PSQI and OHIP component scores were discerned between the BC and DC groups contingent on TMD pain. Total-DASS was moderately correlated to total-PSQI/OHIP (rs = 0.41-0.63). CONCLUSION: The covid-19 pandemic did not appear to exacerbate psychological distress but affected sleep and increased unease over TMD dysfunction.

The influence of the COVID-19 pandemic, sex, and age on temporomandibular disorders subtypes in East Asian patients: a retrospective observational study.

BACKGROUND: Despite its major existential, societal, and health impacts, research concerning the COVID-19 pandemic and Temporomandibular disorders (TMDs) is still limited. This study examined the effect of the pandemic on TMD subtypes and elucidated the influence of the pandemic, sex, and age on the prospect of pain-related (PT) and/or intra-articular (IT) TMDs in East Asian patients. METHODS: Data were accrued from consecutive new patients attending two university-based TMD/orofacial pain clinics in China and South Korea, 12 months before (BC; Mar 2019-Feb 2020) and during (DC; Mar 2020-Feb 2021) the COVID-19 pandemic. TMD diagnoses were derived from pertinent symptoms, signs, and radiographic findings according to the Diagnostic Criteria for TMDs (DC/TMD) methodology. Patients were subsequently categorized into those with PT, IT, and combined TMDs (CT) and also stratified by attendance period, sex, and age groups (adolescents/young adults [AY] and middle-aged/older adults [MO]) for statistical analyses using Chi-square/Mann-Whitney U tests and logistic regression analyses (α = 0.05). RESULTS: The BC and DC groups comprised 367 (75.2% females; 82.8% AY) and 471 (74.3% females; 78.3% AY) patients correspondingly. No significant differences in sex and age group distributions were observed. The DC group had significantly more PT/IT conditions with higher prevalence of myalgia, headache, and degenerative joint disease than the BC group. Univariate analyses showed that PT/CT was associated with sex and age, whereas IT was related to the pandemic and age. However, multivariate analyses indicated that the odds of PT were affected by sex (OR = 2.52) and age (OR = 1.04) while the odds of IT (OR = 0.95) and CT (OR = 1.02) were influenced by age only. CONCLUSIONS: The COVID-19 pandemic, as an impact event, did not influence the prospect of PT and/or IT. Sex and age appeared to play more crucial roles in the development of PT and IT/CT respectively.

DC/TMD axis I subtyping: generational and gender variations among East Asian TMD patients.

OBJECTIVES: This study examined the generational-gender distinctions in Diagnostic Criteria for Temporomandibular disorders (DC/TMD) subtypes among East Asian patients. METHODS: Consecutive "first-visit" TMD patients presenting at two university-based TMD/orofacial pain clinics in China and South Korea were enlisted. Demographic information along with symptom history was gathered and clinical examinations were performed according to the DC/TMD methodology. Axis I physical diagnoses were rendered with the DC/TMD algorithms and categorized into painful and non-painful TMDs. Patients were categorized into three birth cohorts, specifically Gen X, Y, and Z (born 1965-1980, 1981-1999, and 2000-2012 respectively) and the two genders. Data were evaluated using Chi-square/Kruskal-Wallis plus post-hoc tests and logistic regression analyses (α = 0.05). RESULTS: Gen X, Y, and Z formed 17.2%, 62.1%, and 20.7% of the 1717 eligible patients examined (mean age 29.7 ± 10.6 years; 75.7% women). Significant differences in prevalences of arthralgia, myalgia, headache (Gen X ≥ Y > Z), and disc displacements (Gen Z > Y > X) were observed among the three generations. Gen Z had substantially fewer pain-related and more intra-articular conditions than the other generations. Women presented a significantly greater frequency of degenerative joint disease and number of intra-articular conditions than men. After controlling for generation-gender interactions, multivariate analyses showed that "being Gen X" and female increased the risk of painful TMDs (OR = 2.20) and reduced the odds of non-painful TMDs (OR = 0.46). CONCLUSIONS: Generational-gender diversities in DC/TMD subtypes exist and are important for guiding TMD care and future research endeavors.

Descending serotonergic modulation from rostral ventromedial medulla to spinal trigeminal nucleus is involved in experimental occlusal interference-induced chronic orofacial hyperalgesia.

BACKGROUND: Dental treatment associated with unadaptable occlusal alteration can cause chronic primary myofascial orofacial pain. The serotonin (5-HT) pathway from the rostral ventromedial medulla (RVM) exerts descending modulation on nociceptive transmission in the spinal trigeminal nucleus (Sp5) and facilitates chronic pain. The aim of this study was to investigate whether descending 5-HT modulation from the RVM to the Sp5 is involved in the maintenance of primary myofascial orofacial hyperalgesia after persistent experimental occlusal interference (PEOI) or after delayed removal of experimental occlusal interference (REOI). METHODS: Expressions of 5-HT3A and 5-HT3B receptor subtypes in the Sp5 were assessed by immunofluorescence staining and Western blotting. The release and metabolism of 5-HT in the Sp5 were measured by high-performance liquid chromatography. Changes in the pain behavior of these rats were examined after specific pharmacologic antagonism of the 5-HT3 receptor, chemogenetic manipulation of the RVM 5-HT neurons, or selective down-regulation of 5-HT synthesis in the RVM. RESULTS: Upregulation of the 5-HT3B receptor subtype in the Sp5 was found in REOI and PEOI rats. The concentration of 5-HT in Sp5 increased significantly only in REOI rats. Intrathecal administration of Y-25130 (a selective 5-HT3 receptor antagonist) dose-dependently reversed the hyperalgesia in REOI rats but only transiently reversed the hyperalgesia in PEOI rats. Chemogenetic inhibition of the RVM 5-HT neurons reversed the hyperalgesia in REOI rats; selective down-regulation of 5-HT in advance also prevented the development of hyperalgesia in REOI rats; the above two manipulations did not affect the hyperalgesia in PEOI rats. However, chemogenetic activation of the RVM 5-HT neurons exacerbated the hyperalgesia both in REOI and PEOI rats. CONCLUSIONS: These results provide several lines of evidence that the descending pathway from 5-HT neurons in the RVM to 5-HT3 receptors in the Sp5, plays an important role in facilitating the maintained orofacial hyperalgesia after delayed EOI removal, but has a limited role in that after persistent EOI.

Deep learning-based evaluation of the relationship between mandibular third molar and mandibular canal on CBCT.

OBJECTIVES: The objective of our study was to develop and validate a deep learning approach based on convolutional neural networks (CNNs) for automatic detection of the mandibular third molar (M3) and the mandibular canal (MC) and evaluation of the relationship between them on CBCT. MATERIALS AND METHODS: A dataset of 254 CBCT scans with annotations by radiologists was used for the training, the validation, and the test. The proposed approach consisted of two modules: (1) detection and pixel-wise segmentation of M3 and MC based on U-Nets; (2) M3-MC relation classification based on ResNet-34. The performances were evaluated with the test set. The classification performance of our approach was compared with two residents in oral and maxillofacial radiology. RESULTS: For segmentation performance, the M3 had a mean Dice similarity coefficient (mDSC) of 0.9730 and a mean intersection over union (mIoU) of 0.9606; the MC had a mDSC of 0.9248 and a mIoU of 0.9003. The classification models achieved a mean sensitivity of 90.2%, a mean specificity of 95.0%, and a mean accuracy of 93.3%, which was on par with the residents. CONCLUSIONS: Our approach based on CNNs demonstrated an encouraging performance for the automatic detection and evaluation of the M3 and MC on CBCT. Clinical relevance An automated approach based on CNNs for detection and evaluation of M3 and MC on CBCT has been established, which can be utilized to improve diagnostic efficiency and facilitate the precision diagnosis and treatment of M3.

Functional, physical and psychosocial impact of degenerative temporomandibular joint disease.

OBJECTIVES: This study evaluated the functional, physical and psychosocial impacts of TMJ degenerative joint disease (DJD). The bearing of TMJ osteoarthrosis/osteoarthritis and early/late TMJ DJD on oral health-related quality of life (OHRQoL) were also compared. METHODS: Participants were enrolled from a TMD/oro-facial pain centre. Those diagnosed with intra-articular conditions based on the Diagnostic Criteria for Temporomandibular disorders (DC/TMD) were subjected to CBCT assessment and categorised into four discrete groups: NN-no TMJ DJD and no arthralgia; NA-no TMJ DJD with arthralgia; TO-TMJ osteoarthrosis; and TR-TMJ osteoarthritis. The TO/TR groups were subdivided into early/late TMJ osteoarthrosis (EO/LO) and osteoarthritis (ER/LR). OHRQoL was examined using the OHIP-TMD, and data were appraised with the Kruskal-Wallis/Mann-Whitney U tests (α = 0.05). RESULTS: The study participant (n = 358) had a mean age of 31.85 ± 12.39 years (85.6% women). Frequencies of the TMD groups were as follows: NN-23.2%; NA-27.1%; TO-19.0%; and TR-30.7%. Participants with TR/NA had significantly worse OHRQoL than those with TO/NN. Additionally, participants with ER/LR reported significantly poorer OHRQoL than their counterparts with EO/LO. For all TMD groups and TMJ DJD subgroups, the psychological discomfort domain was generally the most impaired. Differences in global OHIP scores were significant between participants with and without arthralgia (i.e., NA-NN, ER-EO and LR-LO). CONCLUSIONS: The presence of TMJ pain appeared to impair OHRQoL more than the severity of TMJ DJD. As psychological domains were most impacted, psychosocial care should be incorporated when managing patients with painful TMJ DJD.

CXCR3 signalling partially contributes to the pathogenesis of neuropathic pain in male rodents.

BACKGROUND: Currently, there is a lack of effective therapy for chronic pain. Increasing evidence has shown that chemokines and their correlative receptors involved in the neuron-glial cell cross-talk could contribute to the pathogenesis of neuropathic pain. Our previous studies suggested that CXCR3 expression was elevated in the spinal dorsal horn after nerve injury. OBJECTIVES: In this study, we aimed to explore the role of CXCR3 signalling in chronic pain modulation. METHODS: Reverse transcription quantitative PCR and Western blotting were used to measure the expression of CXCR3 and its ligands in the spinal cord following chronic constriction injury (CCI) of the sciatic nerve. Cxcr3 -knockout mice were used to observe the effect of the receptor on pain-related behaviour and microglial activation. Immunohistochemistry was used to investigate the expression of two activation markers for spinal microglia, Iba-1 and phosphorylated-p38 (p-p38) in these mice. RESULTS: The expression of CXCR3 and its ligand CXCL11 was upregulated in the lumbar dorsal horn of the spinal cord in CCI models. In Cxcr3 -knockout mice, CCI-induced tactile allodynia and thermal hyperalgesia were observed to be alleviated during the early stage of pain processing. Meanwhile, the expression of the glial activation markers, namely, Iba-1 and p-p38, was decreased. CONCLUSION: Our results demonstrate that CXCR3 could be a key modulator involved in pain modulation of the spinal cord; therefore, CXCR3-related signalling pathways could be potential targets for the treatment of intractable pathological pain.

Comparison of psychological states and oral health-related quality of life of patients with differing severity of temporomandibular disorders.

BACKGROUND: Studies on temporomandibular disorder (TMD) severity in patient populations are scarce. OBJECTIVES: This study sought to compare the psychological states and oral health-related quality of life (OHRQoL) among patients with differing TMD severity. METHODS: Adult patients (≥18 years old) with and without (controls) TMDs were recruited from the TMD/oro-facial pain centre and prosthodontics department, respectively. The presence and severity of TMDs were established with the Fonseca Anamnestic Index (FAI), and TMD diagnoses were confirmed with the Diagnostic Criteria for TMDs (DC/TMD). Psychological states and OHRQoL were examined with the Depression, Anxiety, Stress Scales-21 (DASS-21) and Oral Health Impact Profile for TMDs (OHIP-TMD). Data were subjected to chi-square, Kruskal-Wallis/Mann-Whitney U tests and Spearman's correlation (α = .05). RESULTS: A total of 961 participants with a mean age of 32.99 ± 13.14 years (71.19% women) were assessed. Frequencies of the various TMD categories were as follows: no TMD/controls (12.07%), mild TMD (24.56%), moderate TMD (40.37%) and severe TMD (23.00%). The three most common TMD-related symptoms were TMJ noises, mouth opening difficulty and muscle pain. Participants with moderate/severe TMD presented a higher proportion of intra-articular and/or combined disorders. They reported significantly higher levels of depression, anxiety, stress and poorer OHRQoL than their counterparts with no/mild TMD (p < .001). Moderate-to-strong correlations were observed between FAI and DASS-21/OHIP-TMD scores (rs = 0.42-0.72). CONCLUSIONS: Patients with moderate/severe TMD had significantly higher levels of psychological disturbance and poorer OHRQoL. As OHRQoL and psychological states are correlated, psychological well-being must be considered when managing patients with moderate/severe TMDs.

Astrocytes in the rostral ventromedial medulla contribute to the maintenance of oro-facial hyperalgesia induced by late removal of dental occlusal interference.

BACKGROUND: Astrocytes in the rostral ventromedial medulla (RVM) contribute to descending pain modulation, but their role in oro-facial pain induced by persistent experimental dental occlusal interference (PEOI) or following EOI removal (REOI) is unknown. OBJECTIVE: To explore the involvement of RVM astrocytes in PEOI-induced oro-facial hyperalgesia or its maintenance following REOI. METHODS: Male rats were randomly assigned into five groups: sham-EOI, postoperative day 6 and 14 of PEOI (PEOI 6 d and PEOI 14 d), postoperative day 6 following REOI on day 3 (REOI 3 d) and postoperative day 14 following REOI on day 8 (REOI 8 d). The nociceptive head withdrawal threshold (HWT) and activities of RVM ON- or OFF-cells were recorded before and after intra-RVM astrocyte gap junction blocker carbenoxolone (CBX) microinjection. RVM astrocytes were labelled immunohistochemically with glial fibrillary acidic protein (GFAP) and analysed semi-quantitatively. RESULTS: Persistent experimental dental occlusal interference-induced oro-facial hyperalgesia, as reflected in decreased HWTs, was partially inhibited by REOI at day 3 but not at day 8 after EOI placement. Increased GFAP-staining area occurred only in REOI 8 d group in which CBX could inhibit the maintained hyperalgesia; CBX was ineffective in inhibiting hyperalgesia in PEOI 14 d group. OFF-cell activities showed no change, but the spontaneous activity and responses of ON-cells were significantly enhanced that could be suppressed by CBX in REOI 8 d group. CONCLUSION: Rostral ventromedial medulla astrocytes may not participate in PEOI-induced oro-facial hyperalgesia or hyperalgesia inhibition by early REOI but are involved in the maintenance of oro-facial hyperalgesia by late REOI.

Diagnostic accuracy of the short-form Fonseca Anamnestic Index in relation to the Diagnostic Criteria for Temporomandibular Disorders.

STATEMENT OF PROBLEM: Screening for temporomandibular disorders (TMDs) is important in research and clinical practice. The short-form Fonseca Anamnestic Index (SFAI) was recently introduced but had only been validated for muscle disorders. PURPOSE: The purpose of this clinical study was to determine the diagnostic accuracy of the SFAI and its discrete and pooled items in relation to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) benchmark. MATERIAL AND METHODS: A total of 866 consecutive participants with TMDs and 57 TMD-free controls (aged ≥18 years) were recruited. The participants (n=923; mean age 32.8 ±13.3 years; women 79.2%) answered the FAI, and TMD diagnoses were derived based on the DC/TMD protocol and algorithms. The 5-item SFAI, which comprised 2 pain-related and 3 function-related TMD questions, was subsequently acquired and assessed with reference to the DC/TMD diagnoses. The receiver operating characteristics (ROC) was used to verify accuracy (area under the curve [AUC]) and the best cutoff points. Sensitivity, specificity, predictive values, and likelihood ratios were also examined. RESULTS: Pain-related (PT) and intra-articular (IT) TMDs were present in 48.3% (446/923) and 82.7% (763/923) of the participants, respectively. The SFAI demonstrated high accuracy for identifying all TMDs, PT, and IT (AUC of 0.97, 0.99, and 0.97, respectively). The best cutoff points were 12.5 for all TMDs/IT and 17.5 for PT. Sensitivity of the SFAI ranged from 90.7% to 97.5% while specificity varied from 93.0% to 96.5%, with the highest values for PT. As positive predictive values (99.4% to 99.5%) were greater than negative ones (41.7% to 83.3%), the SFAI was better at detecting the presence than the absence of TMDs. With reference to PT, the sensitivity, and specificity of the 2 discrete and pooled pain-related questions (questions 3 and 4), extended from 82.3% to 99.3% and 77.2% to 96.5% respectively. With regard to IT diagnoses, sensitivity and specificity ranged from 56.0% to 98.3% and 86.0% to 98.3% for the 3 discrete and pooled function-related items (questions 1, 2, and 5). CONCLUSIONS: The SFAI presented high degrees of diagnostic accuracy in relation to the DC/TMD and can be used for screening TMDs. SFAI scores between 15 and 50 points should be used to identify the presence of TMDs, with scores ≥20 points specifying possible pain-related TMDs.

Subtypes of acute and chronic temporomandibular disorders: Their relation to psychological and sleep impairments.

OBJECTIVES: To determine the differences in psychological states and sleep quality in patients with various temporomandibular disorder (TMD) subtypes, and to ascertain the relationships between TMD duration with psychological and sleep impairments. METHODS: A total of 830 TMD patients were recruited categorized into pain-related (PT), intra-articular (IT), and combined (CT) TMD groups. Each group was further divided into acute and chronic subtypes. The Depression, Anxiety, and Stress Scales-21 (DASS-21), and Pittsburgh Sleep Quality Index (PSQI) were used to assess emotional states and sleep problems. RESULTS: Although chronic TMDs generally had higher levels of anxiety, depression, stress, and sleep impairments than acute TMDs, significant differences were only observed for the PT group. Ranking of the mean depression, anxiety, and stress scores was as follows: acute TMDs: CT > PT > IT; chronic TMDs: PT > CT > IT. For both acute and chronic TMDs, the ranking of mean PSQI global and component scores was PT ≥ CT ≥ IT. Logistic regression analyses indicated that stress (ORs = 4.40) and depression (ORs = 2.82) increased the risks of chronic pain-related TMDs (p < .05). CONCLUSIONS: Chronic pain-related TMDs are associated with high levels of psychological distress and poorer sleep, while chronic intra-articular TMDs are not. Stress and depression increased the probability of chronic pain-related TMDs.

Comparison of emotional disturbance, sleep, and life quality in adult patients with painful temporomandibular disorders of different origins.

OBJECTIVES: This study compared the differences in emotional disturbance, sleep, and life quality among adult patients with temporomandibular (TMD) muscle and/or joint pain. MATERIALS AND METHODS: The study involved an analytical cross-sectional design. A total of 420 consecutive patients diagnosed with pain-related TMDs based on the Diagnostic Criteria for TMDs (DC/TMD) were recruited from a TMD referral centre and stratified into three groups, namely muscle pain (MP; n = 50), joint pain (JP; n = 329), and combined muscle-joint pain (CP; n = 41). Emotional disturbance, sleep quality, and oral health-related quality of life (OHRQoL) were assessed with the Depression, Anxiety, and Stress Scale-21 (DASS-21), Pittsburgh Sleep Quality Index (PSQI), and Oral Health Impact Profile-TMDs (OHIP-TMDs) respectively. Statistical analyses were performed using the chi-square test, one-way ANOVA, and Pearson's correlation (p < 0.05). RESULTS: Mean age for the three pain groups (females = 349; males = 71) ranged from 37.15 ± 14.91 to 38.60 ± 14.37 years (p = 0.973). Ranking of depression, anxiety, and stress scores was as follows: CP > MP > JP. Significant differences in emotional disturbances were observed (p < 0.001). CP patients had significantly poorer sleep quality than those with JP (p = 0.004). Moreover, OHRQoL was also significantly more impaired as compared to both MP (p = 0.006) and JP (p < 0.001) patients. Correlations between global PSQI and OHIP-TMDs scores were weak to moderate (rs = 0.30-0.47). CONCLUSIONS: Patients with combined muscle-joint pain presented higher levels of emotional disturbance than those with only MP or JP. They also had significantly poorer sleep quality and lower OHRQoL. CLINICAL RELEVANCE: Emotional and sleep health must be considered in the management of painful TMDs.

Age-related differences in diagnostic categories, psychological states and oral health-related quality of life of adult temporomandibular disorder patients.

OBJECTIVES: The peak prevalence of temporomandibular disorders (TMDs) may occur in middle age. This study determined the proportion of matured adults seeking TMD treatment and compared their diagnostic, psychological and oral health-related quality-of-life (OHRQoL) profiles to younger patients. METHODS: Adult subjects were recruited from a tertiary TMD centre and assigned to three age groups, namely 18-44 years (young adults [YA]), 45-64 (middle-aged adults [MA]) and ≥65 (old adults [OA]). TMD diagnoses were established with the Diagnostic Criteria for TMDs and categorised as pain-related (PT), intra-articular (IT) and combined (CT) TMDs. Psychological states and OHRQoL were assessed with the Depression, Anxiety, and Stress Scale-21 (DASS-21) and Oral Health Impact Profile-TMDs (OHIP-TMDs). Demographic, DASS-21, and OHIP-TMDs data were analysed using chi-square test, one-way ANOVA and Pearson's correlation (P < .05). RESULTS: Middle-aged (19.7%; 136/692) and old (4.0%; 28/692) adults comprised about a quarter of the TMD patients. Although gender distribution was comparable, significant differences in TMD categories were observed (P < .001). Pain-related TMDs were more prevalent in the MA/OA groups while intra-articular TMDs were more frequent in the YA group. No significant difference in DASS-21 and total OHIP scores was noted among three groups. However, the MA and OA groups had significantly lower OHRQoL in the physical pain domain. Correlations between DASS-21 and OHIP-TMDs scores varied with age and ranged from rs  = 0.47-0.92. CONCLUSIONS: Matured patients constituted a quarter of TMD cohort and presented higher frequencies of painful TMDs. They have similar psychological profiles to younger patients but experienced lower OHRQoL in physical pain domain.

Psychometric evaluation of the Chinese version of the Fonseca anamnestic index for temporomandibular disorders.

BACKGROUND: The Fonseca anamnestic index (FAI) offers a simple, low-cost, patient-reported method for screening temporomandibular disorders (TMDs). OBJECTIVES: This study described the development of the Chinese version of the FAI (FAI-C) and examined its reliability and validity when compared to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). METHODS: The FAI-C was created by translation and cross-cultural adaptation of the English instrument following international guidelines. Psychometric evaluation of the FAI-C was carried out on a sample of 613 patients with TMDs and 57 controls. Reliability of the FAI-C was determined by means of internal consistency and test-retest methods while validity was ascertained by criterion-related validity. Criterion validity was examined via Cohen's kappa, sensitivity and specificity when compared with DC/TMD Axis I diagnoses. RESULTS: Cronbach's alpha value (internal consistency) for total FAI-C score was 0.669, and intra-class correlation coefficient (ICC) value (test-retest reliability) was 0.823. For criterion validity, kappa coefficient value was 0.633 while sensitivity and specificity was 95.9% and 71.9%, respectively. CONCLUSION: The Chinese version of the FAI demonstrated acceptable reliability and good validity. The FAI-C could thus be used as an instrument for screening TMDs in Chinese literate populations.

Increased chemokine RANTES in synovial fluid and its role in early-stage degenerative temporomandibular joint disease.

BACKGROUND: Degenerative joint disease (DJD) of the temporomandibular joints (TMJs) in adolescents and young adults is closely associated with disc displacement without reduction (DDw/oR). OBJECTIVE: This study aimed to determine the pathogenesis of early-stage TMJ DJD induced by DDw/oR. METHODS: 31 female subjects aged 12-30 years were enrolled, comprising 12 patients with DDw/oR without DJD, 13 with DDw/oR and early-stage DJD, and 6 healthy volunteers. The synovial fluid samples of the subjects were screened for 27 inflammatory-related cytokines using multiple cytokine array. Significantly increased cytokines and a key regulator of osteoclastogenesis "receptor activator of nuclear factor-κB ligand" (RANKL) were further determined by sandwich immunoassay. These factors were also assessed for the possible pathophysiologic actions on RAW264.7 cell proliferation, migration, osteoclastogenesis and bone-resorbing activity using Cell Counting Kit-8, Transwell system, tartrate-resistant acid phosphatase staining and osteo assay plates. RESULTS: Macrophage-derived inflammatory protein-1 beta (MIP-1ß) and regulated upon activation normal T cell expressed and secreted (RANTES) were found to vary significantly in relation to the controls. In contrast to an unchanged concentration of RANKL, a strong increase in the level of RANTES was detected in subjects with DDw/oR and early-stage DJD. MIP-1ß concentrations were only elevated in subjects with DDw/oR without DJD. Functionally, both MIP-1ß and RANTES could enhance macrophage migration in a concentration-dependent manner, while only RANTES exhibited a promoting effect on osteoclast formation and bone-resorbing activity. CONCLUSIONS: Chemokine RANTES was significantly upregulated and might be a key regulator of osteoclastogenesis contributing to DDw/oR-induced early-stage TMJ DJD.

Contribution of microglial reaction to increased nociceptive responses in high-fat-diet (HFD)-induced obesity in male mice.

The progressive increase in the prevalence of obesity in the population can result in increased healthcare costs and demands. Recent studies have revealed a positive correlation between pain and obesity, although the underlying mechanisms still remain unknown. Here, we aimed to clarify the role of microglia in altered pain behaviors induced by high-fat diet (HFD) in male mice. We found that C57BL/6CR mice on HFD exhibited enhanced spinal microglial reaction (increased cell number and up-regulated expression of p-p38 and CD16/32), increased tumor necrosis factor-α (TNF-α) mRNA and brain-derived neurotrophic factor (BDNF) protein expression as well as a polarization of spinal microglial toward a pro-inflammatory phenotype. Moreover, we found that using PLX3397 (a selective colony-stimulating factor-1 receptor (CSF1R) kinase inhibitor) to eliminate microglia in HFD-induced obesity mice, inflammation in the spinal cord was rescued, as was abnormal pain hypersensitivity. Intrathecal injection of Mac-1-saporin (a saporin-conjugated anti-mac1 antibody) resulted in a decreased number of microglia and attenuated both mechanical allodynia and thermal hyperalgesia in HFD-fed mice. These results indicate that the pro-inflammatory functions of spinal microglia have a special relevance to abnormal pain hypersensitivity in HFD-induced obesity mice. In conclusion, our data suggest that HFD induces a classical reaction of microglia, characterized by an enhanced phosphorylation of p-38 and increased CD16/32 expression, which may in part contribute to increased nociceptive responses in HFD-induced obesity mice.

Condylar repair and regeneration in adolescents/young adults with early-stage degenerative temporomandibular joint disease: A randomised controlled study.

BACKGROUND: Anterior repositioning splint (ARS) can facilitate regenerative condylar remodelling. OBJECTIVE: To determine the effect of ARS on osseous condylar changes in adolescents/young adults with early-stage degenerative joint disease (DJD). METHODS: Sixty-nine patients with early-stage temporomandibular joint (TMJ) DJD based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and cone beam computed tomography (CBCT) imaging were recruited and randomly allocated to two treatment groups: (a) conservative therapy with ARS and (b) conservative therapy without ARS. Subjects with acute TMJ closed-lock had their displaced discs physically reduced by mandibular manipulation prior to ARS therapy. Clinical and CBCT data of 59 patients (86.4% females, mean age 17.95 ± 4.53 years, 67 joints) were attained pre- and at 6 or 12 months post-treatment. Osseous changes after treatment were categorised into (a) progressed, (b) unchanged, (c) repaired (remodelled without new bone formation) and (d) regenerated (remodelled with new bone formation). Statistical analysis including chi-square test, independent samples t test or Mann-Whitney U test was conducted. RESULTS: About 85.5% of patients (59/69) completed the study, with 28 subjects (32 joints) in the splint group and 31 (35 joints) in the control group. The occurrence of condylar repair and regeneration was significantly higher with ARS (78.1%/[25/32] of joints) when compared to control group (48.6%/[17/35]) (P < 0.05). Moreover, condylar regeneration was exclusively observed in 50%/(16/32) of joints with ARS. For the 14 joints in splint group that received physical TMJ closed-lock reduction, 85.7%/(12/14) exhibited condylar regeneration. The splint group (3.1%/[1/32]) also had significantly lower incidence of progressive TMJ degeneration than the control (37.1%/[13/35]) (P < 0.001). CONCLUSION: Condylar repair and regeneration in early-stage TMJ DJD are possible, and ideal spatial disc-condyle relationship appears important. The possibility of restoring TMJ form/structure by ARS therapy presents an attractive area of new basic science and clinical research (Bone defect repair in early osteoarthrosis of temporomandibular joint by joint distraction therapy: A randomized controlled trial/ChiCTR-TRC-14005172).