BACKGROUND: The present study is to evaluate the clinical characteristics of patients with temporomandibular disorders (TMD).
METHODS: A total of 3362 TMD patients were included. Each participant had complete medical records according to the diagnostic criteria for temporomandibular disorders (DC/TMD). The clinical characteristics including symptoms and signs in relation to age and gender were analyzed.
RESULTS: The mean age of the patients seeking care was 29.89 ± 13.73Y, and 68.6% of patients were aged 16-35 years. The female-to-male ratio of patients was 2.2: 1, and the average age of males was significantly lower than that of females. The prevalence of clicking symptoms decreased with age, while the prevalence of pain symptoms and limitations in jaw movement increased with age. Females were more likely to have limitations in jaw movement than males. Among the patients with pain, the average visual analogue scale (VAS) was 2.96 ± 1.23. The average VAS score of acute TMD patients (≤ 3 months) was significantly higher than that of chronic TMD patients (> 3 months).
CONCLUSIONS: The majority of TMD patients seeking care were young people. The number and average age of female patients was higher than the males. Female patients were more likely to have limitations in jaw movement than males.

BACKGROUND: Currently, there is still controversy surrounding the relationship between temporomandibular disorders (TMDs) symptoms and jaw functional limitations. We investigated the distribution of TMDs in senior high school students, including both the number and types of symptoms, and assessed their association with jaw functional limitations. Furthermore, we explored sex differences in these associations.
METHODS: This study was conducted at a public high school in Hefei, Anhui Province, China, with data collected from September to October 2022. All subjects completed questionnaires assessing the anamnestic symptoms of TMDs and the Jaw Functional Limitation Scale (JFLS), and examinations were performed by trained dentists according to the Diagnostic Criteria for TMD. Data were analysed using the Kruskal-Wallis, Mann-Whitney U, and Chi-square tests.
RESULTS: The mean age of the participants (N = 2890) was 17.2 ± 0.14 years and 38.9% were females (61.1% were males). Limitations in self-assessed jaw function were associated with the presence of TMDs (P < .05). Participants with more symptoms reported significantly high levels of functional limitations (P < .05). Compared to male adolescents, female adolescents more commonly experienced TMDs pain and tended to have more symptoms (P < .05). However, no sex differences were observed in most associations between TMDs and jaw functional limitations.
CONCLUSIONS: TMDs-positive symptoms are common in adolescents. Female adolescents were more affected by TMDs symptoms than male adolescents. Individuals with more TMDs symptoms have greater jaw functional limitations.

UNASSIGNED: This study aims to investigate the relationship between five sleep traits (insomnia, sleep duration, getting up in morning, snoring, and daytime nap) and temporomandibular disorders (TMD) using bi-directional Mendelian randomization.
UNASSIGNED: The bi-directional Mendelian randomization study was conducted in two stages. Initially, sleep traits were examined as exposures while TMD was evaluated as an outcome, whereas the second step was reversed. The inverse variance weighted (IVW) method and other Mendelian randomization methods were used for analysis. Furthermore, we performed the MR-Egger intercept, MR-PRESSO, Cochran\'s Q test, and \"Leave-one-out\" to assess the levels of pleiotropy and heterogeneity.
UNASSIGNED: The IVW method indicates that getting up in the morning reduces the risk of developing TMD (OR = 0.50, 95% CI 0.30-0.81, p = 0.005), while insomnia may increase the risk of TMD (OR = 2.05, 95% CI 1.10-3.85, p = 0.025). However, other sleep traits are not associated with the risk of TMD, and having TMD does not alter an individual\'s sleep traits. After removing outliers, the results remained robust, with no pleiotropy detected.
UNASSIGNED: Genetically determined difficulty in getting up in the morning and insomnia can increase the risk of TMD. By optimizing sleep, the risk of developing TMD can be reduced. This underscores the importance of sleep in preventing TMD.

BACKGROUND: Syndecan 4 (SDC4), a type I transmembrane proteoglycan, serves as a critical link between chondrocytes and the extracellular matrix.
OBJECTIVE: This study aimed to explore the role of SDC4 in cartilage degeneration of temporomandibular joint osteoathritis (TMJOA).
METHODS: Condylar chondrocytes were stimulated with varying concentrations of recombinant rat interleukin-1β (rrIL-1β) and SDC4 small interfering RNA (si-SDC4). Anti-SDC4 ectodomain-specific antibodies or IgG were intra-articularly administrated in a TMJOA model rats. SDC4 conditional knockout (SDC4-cKO) and Sdc4flox/flox mice were induced TMJOA. Cartilage degeneration was assessed using haematoxylin & eosin (H&E) and safranin O (SO) staining. Protein levels of SDC4, matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase with a thrombospondin motifs 5 (ADAMTS5), tumour necrosis factor α (TNFα), type II collagen (Col-II), aggrecan (ACAN), cleaved caspase 3 (CASP3), Ki67 and related pathways in condylar cartilage were evaluated by immunohistochemical (IHC) staining or western blot assays.
RESULTS: SDC4 expression was evidently increased in MIA-model animals compared to control groups. rrIL-1β stimulation increased the expression of SDC4, MMP3 and ADAMTS5 expression in chondrocytes, while decreasing the expression of Col-II. These effects were reversed by si-SDC4 in vitro. In vivo, SDC4 blockade reduced the death of chondrocytes and the loss of cartilage matrix, which was evidenced by increased expression of Col-II and ACAN, and a decrease in SDC4, MMP13 and cleaved-CASP3-positive cells. Furthermore, the protein levels of ACAN and Ki67 were elevated, and the ERK1/2 and P38 signalling pathways were activated following SDC4 inhibition.
CONCLUSIONS: SDC4 inhibition significantly ameliorates condylar cartilage degeneration, which was mediated, at least partly, through P38 and ERK1/2 signalling. Inhibition of SDC4 may be of great value for the treatment of TMJOA.

BACKGROUND: Poor reporting quality and spin in randomized controlled trial (RCT) abstracts can lead to misinterpretation and distorted interpretation of results.
OBJECTIVE: This methodological study aimed to assess the reporting quality and spin among RCT abstracts on splint therapy for temporomandibular disorders (TMD) and explore the association between spin and potentially related factors.
METHODS: The authors searched PubMed for RCTs on splint therapy for TMD. The reporting quality of each abstract was assessed using the original 16-item CONSORT for abstracts checklist. The authors evaluated the presence and characteristics of spin only in abstracts with nonsignificant primary outcomes according to pre-determined spin strategies. Logistic regression analyses were performed to identify factors associated with the presence of spin.
RESULTS: A total of 148 abstracts were included in the reporting quality evaluation. The mean overall CONSORT score (OCS) was 5.86 (score range: 0-16). Only interventions, objectives and conclusions were adequately reported. Of the 61 RCT abstracts included for spin analysis, spin was identified in 38 abstracts (62.3%), among which 32 abstracts (52.3%) had spin in the Results section and 21 (34.4%) had spin in the Conclusions section. A significantly lower presence of spin was found in studies with exact p-value reporting (OR: 0.170; 95% CI: 0.032-0.887; p = .036) and a two-arm comparison design (OR: 11.777; 95% CI: 2.171-63.877; p = .004).
CONCLUSIONS: The reporting quality of RCT abstracts on splint therapy for TMD is suboptimal and the prevalence of spin is high. More awareness and joint efforts are needed to improve reporting quality and minimize spin.

UNASSIGNED: This study was conducted to investigate the bidirectional causal relationship between obstructive sleep apnea (OSA) and temporomandibular disorders (TMD).
UNASSIGNED: Using an online pooled dataset of genome-wide association studies (GWAS), a two-sample bi-directional Mendelian randomization (MR) method was implemented. Inverse variance weighting was used as the primary analyses approach, and other methods of MR Egger, weighted median method, MR-Egger, Simple mode, and Weighted mode analysis were conducted as supplements to evaluate the causal relationship between OSA and TMD with odds ratios (OR) and 95% confidence interval (CI). Furthermore, the Cochran Q, MR-Egger, and MR-PRESSO approaches were used to perform the heterogeneity test and multiple validity.
UNASSIGNED: The general results of the forward MR analysis indicated that OSA had a significant causal influence on TMD (OR=1.241, 95% CI: 1.009-1.526, P=0.041), but no significant correlation was observed in the reverse MR analysis (IVW: OR=0.975, 95% CI=0.918-1.036, P=0.411).
UNASSIGNED: In summary, our research demonstrated a hereditary causative relationship between OSA and TMD, indicating that appropriate intervention is required for both prevention and treatment of TMD.

UNASSIGNED: The role of autoimmune diseases (ADs) in temporomandibular disorders (TMDs) has been emphasized in observational studies. However, whether the causation exists is unclear, and controversy remains about which specific disorder is destructive in TMDs. This Mendelian randomization (MR) study aims to estimate the causal effect of common ADs on TMDs.
UNASSIGNED: Genetic data from published genome-wide association studies for fourteen common ADs, specifically multiple sclerosis (MS, N = 15,283), ankylosing spondylitis (AS, N = 22,647), asthma (N = 408,422), celiac disease (N = 15,283), Graves\' disease (N = 458,620), Hashimoto thyroiditis (N = 395,640), primary biliary cirrhosis (PBC, N = 11,375), primary sclerosing cholangitis (PSC, N = 14,890), psoriasis vulgaris (N = 483,174), rheumatoid arthritis (RA, N = 417,256), systemic lupus erythematosus (SLE, N = 23,210), Type 1 diabetes (T1D, N = 520,580), inflammatory bowel disease (IBD, N = 34,652), and Sjogren\'s syndrome (SS, N = 407,746) were collected. Additionally, the latest summary-level data for TMDs (N = 228,812) were extracted from the FinnGen database. The overall effects of each immune traits were assessed via inverse-variance weighted (IVW), weighted median, and MR-Egger methods, and performed extensive sensitivity analyses. Finally, 731 immune cell phenotypes (N = 3,757) were analyzed for their mediating role in the significant causality.
UNASSIGNED: Univariable MR analyses revealed that genetically predicted RA (IVW OR: 1.12, 95% CI: 1.05-1.19, p < 0.001) and MS (IVW OR: 1.06, 95% CI: 1.03-1.10, p = 0.001) were associated with increased risk of TMDs. Two out of 731 immune cell phenotypes were identified as causal mediators in the associations of RA with TMDs, including \"CD25++ CD8+ T cell % CD8+ T cell\" (mediation proportion: 6.2%) and \"CD3 on activated CD4 regulatory T cell\" (5.4%). Additionally, \"CD127 on granulocyte\" mediated 10.6% of the total effect of MS on TMDs. No reverse directions, heterogeneity, and pleiotropy were detected in the analyses (p > 0.05).
UNASSIGNED: This MR study provides new evidence regarding the causal impact of genetic predisposition to RA or MS on the increased risk of TMDs, potentially mediated by the modulation of immune cells. These findings highlight the importance for clinicians to pay more attention to patients with RA or MS when consulting for temporomandibular discomfort. The mediating role of specific immune cells is proposed but needs further investigation.

BACKGROUND: Few studies have been conducted on treating temporomandibular disorders (TMDs) with new digital occlusal splints, which has increasingly attracted wide attention.
METHODS: To evaluate the clinical efficacy and quality of life (QoL) of Kovacs digital occlusal splint (KDOS) treatment in patients with TMD.
METHODS: Eighty-nine patients with TMD who were treated using KDOS were analyzed. The patients were divided into three groups according to the Wilkes stage. The clinical symptoms and QoL scores of the patients in each group were recorded before and at least three months after treatment, and the data were statistically analyzed and compared. The relationships between the disease severity, sex, age, and level of QoL before treatment and improvement in the clinical symptoms were analyzed using binary logistic regression.
RESULTS: The mean age and follow-up period of the patients were 28.0 ± 10.4 years and 4.9 ± 2.1 months, respectively. After KDOS treatment, the improvement rates of joint noise and pain were 80.4% and 69.8%, respectively. Additionally, the patients\' maximum mouth opening and global QoL mean scores significantly improved compared to those before treatment (p < 0.001). Binary logistic regression analysis revealed that the factors affecting the improvement in the clinical symptoms were disease severity and level of QoL before treatment.
CONCLUSIONS: KDOS can improve the clinical symptoms and QoL of patients with TMD. Moreover, patients without osteoarthritis and with low pretreatment QoL levels are more likely to demonstrate clinical improvement.
BACKGROUND: The trial was registered with Chinese Clinical Trial Registry (ChiCTR) (ID: ChiCTR2300076518) on 11/10/2023.

UNASSIGNED: To assess the therapeutic efficacy of botulinum toxin type A (BTX-A) for managing myofascial pain related to temporomandibular disorders (TMDs).
UNASSIGNED: This study was conducted according to the PRISMA 2020 statement guidelines. The PubMed, Embase, and Cochrane Library databases were searched. Only randomized controlled trials were included. The primary outcome was a pain score on the visual analog scale, and the secondary outcomes were maximum mouth opening and adverse effects. The Cochrane risk of bias tool was used to assess risk bias. A meta-analysis of studies with the same interventions, controls, assessment methods, and follow-up durations was performed.
UNASSIGNED: A total of 519 studies were retrieved, of which 20 randomized controlled trials were included in the qualitative analysis and six were included in the meta-analysis. The results showed that, compared with placebo, BTX-A injection was more effective at relieving myofascial pain, and its effect was similar to that of conventional methods. However, there was no difference in maximum mouth opening between the two groups. After the study assessment with the RoB 2.0 tool, six studies showed a low risk of bias, 13 studies showed some concerns regarding the reported results, and only one study showed a high risk of bias. Adverse effects of BTX-A injection were observed in four studies.
UNASSIGNED: In conclusion, BTX-A is effective at relieving pain in TMD patients but does not improve mouth opening. To minimize adverse effects, we recommend a low dose of BTX-A for TMD patients who do not experience complete pain relief from conservative treatments.

OBJECTIVE: To evaluate the clinical effectiveness and stability of open suture versus micro-screw anchored disc reduction and fixation in treating disc displacement without reduction in the anterior temporomandibular joint.
METHODS: A total of 38 patients (51 sides) with anterior disc displacement without reduction (ADDwR) of the TMJ treated in our hospital from August 2021 to January 2023 were selected, including 19 cases in group A (23 sides) treated with open temporomandibular joint disc reduction and anchorage, and 19 cases in group B (28 sides) treated with temporomandibular joint disc reduction and suture. The Magnetic Resonance Imaging (MRI) data of the two groups before and after operation were compared to evaluate the effective rate of articular disc reduction, the change of articular disc length, The Maximal Interincisal Opening (MIO) and Numeric Rating Scale (NRS) were measured before and after operation.
RESULTS: In group A, the MRI effective rate 6 months after disc reduction was 95.65 % (22/23), the disc length gain was 1.74 mm, MIO was 40.32±5.067 mm, and NRS was 0.47±0.697. The MRI effective rate 6 months after disc reduction in group B was 100 % (28/28). The disc length gain was 1.78 mm, MIO was 41.58±3.746 mm, and NRS was 0.00. There was no significant difference between the two groups (P > 0.05).
CONCLUSIONS: TMJ disc reduction and suture and open TMJ disc anchorage can effectively reduce the TMJ disc. The TMJ disc stability is high at 6 months after operation, and the pain and mouth opening can be improved, which is worthy of further promotion in clinical practice.