Search Results (658)

Lubricin, also known as proteoglycan 4 (PRG4), is a key glycoprotein involved in boundary lubrication and maintenance of joint homeostasis in the temporomandibular joint (TMJ). However, the clinical evidence regarding synovial fluid (SF) lubricin levels remains limited and fragmented. This scoping review aimed to map and synthesize the available clinical evidence on lubricin levels in patients with temporomandibular disorders (TMDs) and their relationship to clinical outcomes, particularly pain and mandibular mobility. Searches were conducted in PubMed, Scopus, ACM, BASE, Cochrane, ClinicalTrials.gov, and Google Scholar. After duplicate removal and screening, two studies were included in the final synthesis. Preliminary findings from these studies suggest that (SF) lubricin levels may be lower in more advanced TMJ pathology, particularly in degenerative disease. Earlier stages of internal derangement showed lubricin concentrations closer to those observed in healthy controls, whereas advanced internal derangement and osteoarthritic disease were potentially associated with lower levels. One study also reported an inverse correlation between lubricin concentration and pain intensity, while the other demonstrated impaired boundary lubrication in TMD groups. Overall, the available clinical evidence is very limited and insufficient to establish PRG4 as a validated biomarker but suggests a possible association between reduced SF lubricin levels and more advanced TMJ disease. Further well-designed clinical studies are required to confirm these observations and clarify their diagnostic and therapeutic relevance. Full article

Introduction: The relationship between facial form and temporomandibular joint (TMJ) joint-space dimensions remains unclear, particularly regarding variation across different facial shapes. Cone-beam computed tomography (CBCT) provides accurate three-dimensional evaluation of TMJ structures and allows precise assessment of joint-space dimensions. This study aimed to evaluate the association between facial form and TMJ joint-space dimensions (anterior, superior, and posterior) using CBCT. Materials and Methods: This cross-sectional study included 69 adults aged 18–50 years with complete permanent dentition and no signs of temporomandibular disorders based on the Fonseca Index. Facial form was classified as round, oval, or square using standardized two-dimensional photography and an algorithm-based facial classification method (Fisherface-based analysis). CBCT images were obtained using a standardized TMJ protocol, and anterior, superior, and posterior joint spaces were measured bilaterally. Statistical comparisons were performed using ANOVA or Kruskal–Wallis tests (p < 0.05). Results: Most joint-space dimensions showed no significant differences among facial forms. A significant variation was observed only in the left posterior joint space (p = 0.002), where round-faced individuals exhibited the smallest mean value (2.39 ± 1.64 mm) compared with oval (3.77 ± 2.01 mm) and square (6.01 ± 3.12 mm) facial types. Conclusions: Facial form demonstrated minimal influence on temporomandibular joint joint-space dimensions, with differences observed only in the left posterior compartment. These findings suggest that facial-shape assessment may have limited but potentially complementary value in TMJ evaluation. However, the clinical implications should be interpreted cautiously given the predominantly non-significant findings. Full article

Motion dysfunction constitutes a critical clinical manifestation of temporomandibular joint disorder (TMD). Notably, prior research predominantly consists of qualitative clinical descriptions. To better understand the mandibular movement by quantitative analysis, our study proposes a mathematical approach for extracting kinematic parameters and preliminarily illustrates the feasibility and technical advantages through a comparative kinematic parameters analysis of a volunteer opening–closing movement performed in maximum intercuspal position (MIP) and therapeutic position (TP). By decomposing the translational and rotational components of opening–closing movement, the symmetry of the mandibular movement was improved and the maximum mouth opening was increased after wearing a bite-guiding splint. Furthermore, changes in the spatial position of the finite helical axis (FHA) indicated that the FHA position became more stable after wearing the splint, suggesting that this metric has potential kinematic assessment value. Finally, a cushioning effect was observed at the maximum mouth opening when the bite-guiding splint was worn. This approach is expected to provide clinical practice with a high-precision digital assessment tool and a valuable reference for the quantitative evaluation of personalized temporomandibular joint (TMJ) functional rehabilitation. The method could not only conveniently extract the key kinematic parameters of mandible movement but also efficiently evaluate the therapeutic outcomes of clinical intervention. Full article

Background/Objectives: Oral behaviors are increasingly considered relevant within the biopsychosocial framework of temporomandibular disorders, yet their relationship with emotional symptoms remains insufficiently characterized in general adult populations. This study investigated the association between the frequency of oral behaviors and the severity of anxiety and depression symptoms in adults. Methods: This observational, cross-sectional, multicenter study included 460 adults recruited from private dental practices. Oral behaviors were assessed using the Oral Behaviors Checklist (OBC-21), while anxiety and depression were evaluated using Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9). Associations were examined using Spearman correlations and generalized linear models with negative binomial distributions, adjusted for age, sex, and area of residence. Results: OBC-21 scores were positively associated with GAD-7 (R = 0.469, p < 0.001) and PHQ-9 (R = 0.432, p < 0.001). In adjusted models, OBC-21 remained significantly associated with anxiety symptoms (IRR = 1.0292, 95% CI: 1.0187–1.0399, p < 0.001) and depressive symptoms (IRR = 1.0293, 95% CI: 1.0187–1.0400, p < 0.001). Male sex was associated with lower anxiety scores, while age and area of residence were not significant. GAD-7 and PHQ-9 scores were strongly correlated. Conclusions: In this sample of adults attending private dental practices, a higher frequency of oral behaviors was associated with increased anxiety and depression symptoms, independently of age, sex, and area of residence. These findings support the clinical relevance of assessing oral behaviors as part of a biopsychosocial evaluation in dental practice. Full article

Background: Temporomandibular disorders (TMDs) exhibit a marked female predominance, suggesting a potential role for estrogen in their pathophysiology. However, evidence linking estrogen status to TMD remains inconsistent. Objective: To systematically review the association between estrogen-related factors and TMD prevalence and clinical presentation in women. Methods: PubMed, Embase, Scopus, Web of Science, and Google Scholar were searched through September 2025. Observational studies evaluating hormonal contraceptive use, menopausal status, menstrual cycle variation, pregnancy, or estrogen receptor polymorphisms in women with TMD were included. Two reviewers independently performed study selection, data extraction, and risk-of-bias assessment using the Newcastle-Ottawa Scale. Due to substantial heterogeneity, a narrative synthesis was conducted. Results: Seven studies met the inclusion criteria, including six clinical studies involving 2735 participants and one mechanistic supportive study. Moderate-certainty evidence suggested associations between hormonal contraceptive use, menopausal/climacteric status, and increased TMD risk or symptom severity. Additional low-certainty evidence supported associations involving menstrual cycle variation, pregnancy, and estrogen receptor polymorphisms. Conclusions: Current evidence suggests that hormonal factors may influence TMD risk and symptom presentation in women. However, heterogeneity in definitions of hormonal exposure and diagnostic criteria limits definitive conclusions. Further prospective studies using standardized diagnostic protocols and real-time biochemically validated hormonal assessments correlated with clinical symptoms are needed. Full article

Temporomandibular disorders (TMDs) are a group of musculoskeletal conditions characterized by pain, restricted mandibular movement, and joint sounds, which may significantly impair quality of life. Among conservative treatment modalities, low-level laser therapy (LLLT) has gained increasing attention due to its noninvasive nature and its documented analgesic and anti-inflammatory effects. Despite growing evidence supporting the clinical effectiveness of LLLT in the management of TMD-related pain and dysfunction, there is still no consensus regarding the optimal energy density parameters to achieve the most favorable therapeutic outcomes. Therefore, the primary objective of this randomized clinical trial was to determine the optimal energy density of low-level laser therapy. This clinical study evaluated the effects of LLLT applied at different energy densities in patients diagnosed with disk displacement with reduction (DDwR) and myofascial pain. A total of 100 patients were divided into two diagnostic groups, each divided into three subgroups: 940 nm, 1.5 W, 90 J; 940 nm, 3 W, 180 J; and a soft diet group. Laser treatment was performed three times per week for three weeks, for a total of nine sessions. Pain intensity, mandibular movements, and joint sounds were assessed at baseline and at one and six months. Comparable and favorable clinical improvements were achieved in both the laser therapy groups and the soft diet group. The 1.5 W-treated group showed the most significant VAS (visual analog scale) parameter reduction at 6 months. Laser treatment outcomes can be summarized as follows: low-level laser therapy was associated with clinical improvement; however, similar positive outcomes were also observed in the soft diet group. These findings indicate that further controlled studies are needed to better clarify the specific role of laser therapy in the management of temporomandibular disorders. Full article

Low-level laser auriculotherapy (LLLT-AT) is a non-invasive intervention increasingly explored for the management of musculoskeletal pain and psycho-emotional symptoms, which frequently coexist in myogenic temporomandibular disorders (TMDs). This randomized, assessor-blinded, placebo-controlled clinical trial evaluated the effectiveness of LLLT-AT as an adjunct to manual therapy in improving pressure pain threshold (PPT) and anxiety in individuals with myogenic TMDs. Forty-four participants with myogenic TMDs and clinically relevant anxiety were randomly allocated to an experimental group receiving LLLT-AT combined with a standardized myofascial release protocol (n =21) or to a control group receiving sham LLLT-AT with the same manual therapy (n =23). Interventions were delivered twice weekly for three weeks. Primary outcomes were PPT, assessed by pressure algometry, and anxiety, measured using the Generalized Anxiety Disorder–7 (GAD-7) scale. Secondary outcomes included maximum mouth opening range of motion (MMOROM) and mandibular functional limitation assessed by the Jaw Functional Limitation Scale–8 (JFLS-8). Outcomes were evaluated at baseline, post-intervention, and at a four-week follow-up. Both groups demonstrated significant within-group improvements in PPT, MMOROM, and JFLS-8 over time (p < 0.05), with no significant between-group differences (p > 0.05). Between-group analyses showed greater reductions in anxiety in the LLLT-AT group at post-intervention (p = 0.02; Hedges’ g = −1.35) and follow-up (p = 0.02; Hedges’ g = −1.68). LLLT-AT did not confer additional mechanical or functional benefits but was associated with greater reductions in anxiety when used as an adjunct to manual therapy. Full article

Temporomandibular joint osteoarthritis (TMJ-OA) is a multifactorial degenerative disorder characterized by progressive cartilage degradation, subchondral bone remodeling, and chronic inflammation, leading to pain and functional impairment in affected individuals. Despite its clinical impact, effective disease-modifying treatments remain limited, highlighting the need for innovative therapeutic approaches for treating this condition in the future. This manuscript examines the biological rationale, clinical applications, and therapeutic potential of platelet-rich plasma (PRP) and injectable platelet-rich fibrin (i-PRF) in the management of TMJ-OA. As autologous platelet-derived biomaterials, PRP and i-PRF contain high concentrations of growth factors and bioactive molecules that can modulate inflammatory responses and support tissue repair. PRP is associated with a relatively rapid release of these mediators, whereas i-PRF forms a fibrin matrix that may enable a more sustained release profile. Current clinical evidence suggests that both therapies show potential to contribute to pain reduction and may facilitate improvements in mandibular function. However, substantial heterogeneity in preparation protocols, study designs, and outcome measures limits the comparability and generalizability of these findings to the general population. Overall, PRP and i-PRF represent promising, minimally invasive regenerative strategies for managing TMJ-OA. Full article

Background/Objectives: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare genetic disorder causing progressive heterotopic ossification. The dental phenotype has never been systematically characterised. We quantified dental pathologies and oral health-related quality of life across three age groups of genetically confirmed FOP patients and compared them with 156 matched healthy controls (2022–2025). Methods: A total of 52 FOP patients (Group I: 1–5 y, n = 14; Group II: 6–17 y, n = 21; Group III: 18–35 y, n = 17) underwent standardised dental examination (Decayed, Missing, and Filled Teeth index (DMFT), Oral Hygiene Index Simplified (OHI-S), Angle classification, temporomandibular joint (TMJ) assessment), computed tomography (CT) densitometry, sialometry, salivary crystal analysis, and Oral Health Impact Profile-14 (OHIP-14). Statistical analysis used Kruskal–Wallis, Mann–Whitney U, Benjamini–Hochberg false discovery rate (FDR) correction, and effect sizes. Results: Caries (DMFT ≥ 4) was highly prevalent across all FOP groups (82–86%) and significantly higher than in controls (84.6% vs. 38.5%, p < 0.001). Chronic stomatitis showed large age-group differences: 7.1% in Group I vs. 100% in Group III (p < 0.001); it was universal in FOP adults vs. 6.4% in controls. Enamel hypoplasia (21.4% → 58.8%) and Angle class II malocclusion (0% → 47.1%) also showed large age-group differences. Total TMJ disorders were observed in 7.1% of Group I and 100% of Group III (p < 0.001); maximal mouth opening was lower by 17.4 mm in Group III (Cohen’s d = 2.1). Salivary flow rate was 20% lower in adults (0.35 → 0.28 mL/min, p = 0.01). Calcium phosphate crystals were detected in 3/17 adults (17.6%) and showed a preliminary correlation with CT calcification grade (ρ = 0.67, p = 0.003); given the small number of crystal-positive patients, this finding should be considered hypothesis-generating. OHIP-14 total score was higher (worse) in Group III (48.9 vs. 12.4 in Group I, Cohen’s d = 1.95). Conclusions: This cross-sectional study provides a systematic characterisation of the dental phenotype in FOP across three age groups. It shows that chronic stomatitis and TMJ dysfunction become nearly universal by early adulthood, severely impairing quality of life. The correlation between salivary calcium phosphate crystals and CT calcification generates the hypothesis of a non-invasive biomarker, requiring prospective validation. The proposed clinical phenotype and minimally invasive recommendations provide a framework for safer dental management of FOP patients. Full article

Background and Objectives: Temporomandibular disorders (TMDs) are heterogeneous conditions whose clinical expression cannot be fully explained by local or structural findings alone. DC/TMD Axis II provides a psychobehavioral framework for assessing pain, disability, jaw functional limitation, psychological symptoms, and oral behaviors. This conceptual narrative review aimed to clarify how oral behaviors, anxiety, and depressive symptoms can be clinically interpreted together within the DC/TMD Axis II framework. Materials and Methods: A structured search was conducted in PubMed/MEDLINE and Scopus, with records exported in March 2026. Eligible English-language publications were limited to January 2001–March 2026. Google Scholar was used as a supplementary verification source. After deduplication, 2756 records were screened, 87 full-text reports were assessed, and 36 publications were included in the final narrative synthesis. Evidence was synthesized thematically and appraised according to study design, population, diagnostic framework, Axis II instruments, self-report reliance, confounding, and inferential strength. Results: Current literature supports associations between oral behaviors, anxiety, depressive symptoms, pain intensity, and mandibular functional limitation in TMD, especially in painful and functionally impaired profiles. These associations are not uniform across all TMD subtypes and are influenced by factors such as sex, pain burden, comorbidities, and psychosocial context. The Oral Behaviors Checklist is useful for standardizing self-reported oral behaviors, but its interpretation is limited by recall, awareness, and reporting bias. Conclusions: The reviewed evidence supports an interactional interpretation of oral behaviors, psychological symptoms, pain, and jaw function within the DC/TMD Axis II framework. However, because most available studies are cross-sectional and self-reported, this model should be understood as a clinically informed hypothesis supported by convergent associations, not as a confirmed causal pathway. Longitudinal and intervention-based studies are needed to clarify directionality, prognosis, and treatment-response relevance. Full article

Background/Objectives: Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by motor and non-motor symptoms, including pain. Temporomandibular disorder (TMD)-like pain, defined as self-reported pain modified by jaw activities, has been suggested to be more prevalent in PD, but its association with PD severity remains unclear. This study aimed to investigate the association between pain modified by jaw activities and PD severity and the temporal stability of such pain in PD. Methods: This prospective study recruited 28 individuals with PD. Motor symptom severity and disability levels were evaluated using the modified Hoehn and Yahr (mHY) staging and modified Rankin Scale (mRS), respectively. Based on the diagnostic criteria for TMD, a questionnaire assessing pain modified by jaw activities and clinical examination were utilised. Pain modified by jaw activities was reassessed at one, two, and three months. Statistical analyses included Spearman’s rank correlation test and Friedman test, with p < 0.05 considered significant. Results: The participants’ mean age was 69.2 ± 9.6 years; 53.6% were male. Eight participants reported pain modified by jaw activities. Clinical examination identified painful palpation sites in 14 participants, most commonly in the masseter muscle body. Pain modified by jaw activity count showed significant positive correlations with mHY stage (rho = 0.48, p = 0.015) and mRS score (rho = 0.41, p = 0.04). Twenty-four participants completed follow-up, with no significant changes in pain reports over three months. Conclusions: Some individuals with PD may experience persistent TMD-like pain, which is correlated with motor symptom severity and disability levels, highlighting the importance of routine TMD screening in PD. Full article

Background/Objectives: Skeletal Class II malocclusion due to mandibular retrusion is frequently treated with functional appliances, yet their impact on temporomandibular joint (TMJ) structures, specifically the articular disc, remains debated. This systematic review aimed to critically assess quantitative morphological and positional TMJ changes (disc, condyle and glenoid fossa) evaluated with CBCT or MRI in growing skeletal Class II patients treated with functional appliances and to explore whether these changes are associated with the onset or prevention of temporomandibular disorders (TMDs). Methods: The review followed PRISMA guidelines and was registered in PROSPERO (CRD420251028803). Electronic searches were performed in PubMed, Scopus, Web of Science, Cochrane Library, and Embase from inception to December 2025, complemented by manual screening. Inclusion criteria comprised controlled clinical studies in patients aged 8–16 years with skeletal Class II malocclusion due to mandibular deficiency, treated with removable or fixed functional appliances, with pre- and post-CBCT/MRI quantitative TMJ assessment. Risk of bias was evaluated using RoB 2 (RCTs) and ROBINS-I (non-randomized studies); overall certainty was appraised with GRADE. Results: From 937 records, 8 studies met the inclusion criteria. Articular disc outcomes were reported in fewer studies: disc position/morphology was generally stable, and when changes were observed they were favourable (partial improvement/normalization in selected cases). Importantly, no included study reported new treatment-induced disc displacement or new-onset TMD symptoms at the end of treatment. Across studies, the most consistent findings concerned condylar adaptations, commonly described as anterior and/or superior positional changes and remodelling of the condyle–fossa unit. Evidence certainty was limited by heterogeneity and methodological constraints, resulting in low to very low confidence for several outcomes. Conclusions: Functional appliance therapy in growing skeletal Class II patients may be associated with TMJ adaptations, predominantly involving the mandibular condyle, while limited available data may suggest disc stability and no reported short-term clinical TMD onset in included controlled studies. However, due to the limited and heterogeneous evidence base, these findings should be interpreted cautiously, and well-designed prospective studies with standardized 3D imaging outcomes and longer follow-up are needed, particularly for disc-specific endpoints. Full article

Parkinson’s disease (PD) is traditionally defined by dopaminergic loss in the substantia nigra, yet its heterogeneous phenotypes and prodromal trajectories challenge a linear, dopamine-centered model. The α-synuclein origin and connectome (SOC) model proposes two major trajectories: a brain-first pathway, with the pathology initiating in limbic and brainstem structures and spreading ipsilaterally to the nigrostriatal system, and a body-first pathway, with the pathology originating in enteric and peripheral autonomic nerves before ascending to the brain. In this review, we integrate the SOC model into a broader framework, reconceptualizing PD as a progressive disorder of spatial–temporal symmetry. Spatial symmetry encompasses left–right and cranio-caudal balance of neural and musculoskeletal systems, whereas temporal symmetry denotes the coherence of biological rhythms from circadian and autonomic cycles, coupled with metabolic health and mitochondrial function, to sub-second timing governed by dopaminergic and basal ganglia–cortical network dynamics. We outline how systemic insulin resistance and mitochondrial stress erode temporal symmetry, while cranio-cervical malalignment and temporomandibular disorders perturb spatial symmetry. We discuss the neurobiological implementation of these symmetry axes via large-scale networks and dopaminergic modulation of spatial–temporal sensorimotor dynamics, framing PD as a multiscale symmetry-breaking process, and explore the implications for symmetry-oriented biomarkers, subtyping, and future interventions. Full article

Background and Objectives: Temporomandibular disorders (TMDs) are prevalent conditions affecting the temporomandibular joint and associated musculature, arising from a complex interplay of biomechanical, neuromuscular, and psychosocial factors. Increasing evidence supports functional interconnections among the TMJ, cervical spine, and shoulder girdle, suggesting that dysfunction in one region may influence others; however, these relationships remain incompletely understood. This study aimed to evaluate the association between scapulohumeral trauma, postural abnormalities, and TMDs, and to assess their evolution following interdisciplinary rehabilitation. Materials and Methods: A retrospective observational study with prospective follow-up was conducted in patients with scapulohumeral fractures associated with TMD and postural abnormalities. Postural parameters and the clinical features of temporomandibular disorders (TMDs) were evaluated at baseline and follow-up using a structured clinical assessment informed by the DC/TMD framework, together with clinical examination, electromyographic analysis, and mandibular mobility measurements. Postural evaluation was performed using digital baropodometric analysis (Free Med™ platform with FreeStep™ software, standard Medica sensor, Rome, Italy. Patients received individualized multidisciplinary treatment, including orthopaedic rehabilitation, occlusal splint therapy, physiotherapy (twice weekly), pharmacological management, and odonto-periodontal care. Statistical analyses were performed using non-parametric tests (p < 0.05). Results: Significant postural improvement was observed (p < 0.01), with the proportion of patients with normal posture increasing from 0% to 22.2% and the proportion with moderate forward lean decreasing from 53.3% to 15.6%. TMD severity decreased progressively across evaluations (Friedman χ² = 72.35, p < 0.01). No statistically significant differences were found between treatment groups with respect to postural outcomes, although descriptive differences in TMD improvement were observed at later evaluation points. Conclusions: Interdisciplinary rehabilitation was associated with significant improvements in both postural alignment and TMD severity. Scapulohumeral trauma may be associated with alterations in TMJ function and overall posture, while multimodal therapy supports functional recovery. Further randomized controlled studies are needed to confirm these findings. Full article

Background/Objectives: Intra-articular injectable platelet-rich fibrin (I-PRF) is increasingly used in the management of joint-origin temporomandibular joint (TMJ) disorders, but variability in follow-up TMJ disease severity remains substantial. This study assessed whether baseline oral behaviors were associated with follow-up TMJ disease severity after intra-articular I-PRF therapy, using baseline-adjusted analyses of follow-up HI. Methods: This secondary exploratory cohort analysis was conducted within the framework of a registered clinical trial (NCT05883982). Fifty-one consecutive adult patients treated with intra-articular I-PRF were included. Baseline oral behaviors were assessed using the Oral Behaviors Checklist (OBC-21), and TMJ disease severity was quantified using the Helkimo Index (HI) at baseline and final follow-up. Associations between baseline predictors and follow-up HI were evaluated using baseline-adjusted linear regression models including baseline HI as a covariate. Results: Mean (SD) HI decreased descriptively from 7.0 (6.2) at baseline to 2.5 (3.0) at final follow-up (p < 0.001). Baseline HI was strongly associated with follow-up HI (β = 0.32, 95% CI 0.22 to 0.41, p < 0.001), whereas symptom duration (β = 0.02, 95% CI −0.10 to 0.15, p = 0.70) and injection laterality (β = −0.42, 95% CI −1.73 to 0.89, p = 0.52) were not. No OBC-21 item showed a clear baseline-adjusted association with follow-up HI after correction for multiple comparisons. The largest absolute baseline-adjusted regression coefficients were observed for awake bruxism (β = 0.80, 95% CI 0.08 to 1.52, FDR-adjusted p = 0.60) and singing (β = −0.58, 95% CI −1.41 to 0.25, FDR-adjusted p = 0.83). Conclusions: Baseline oral behaviors did not emerge as strong standalone baseline-adjusted factors associated with follow-up HI after intra-articular I-PRF therapy. However, the observed associations may still have been influenced by baseline disease severity dimensions not fully captured by total baseline HI, such as structural disease stage, pain intensity, psychosocial burden, or other unmeasured clinical severity features. The observed nominal and directional item-level patterns should be interpreted only as hypothesis-generating and require confirmation in larger, better-characterized cohorts. Full article