Temporomandibular disorders (TMD) are the most common cause of non-dental orofacial pain, affecting about 1/3 of the population worldwide. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I is recognized as the international gold standard for the clinical and research diagnosis of TMD; however, no validated Romanian version has been available to date. The aim of the present study was to translate and culturally adapt the DC/TMD Axis I into Romanian, and to evaluate its criterion validity and interand intra-examiner reliability. This cross-sectional methodological study followed the Beaton et al. and DC/TMD translation guidelines. The process included forward-backward translation, an expert panel review, and pre-testing on 20 patients to ensure semantic and conceptual equivalence. A total of 140 Romanian-speaking adults (mean age: 34.7 ±12.1 years; 70.7% women) were examined by 2 calibrated clinicians. Criterion validity was assessed against an expert-consensus reference diagnosis. Interand intra-examiner reliability for categorical variables was analyzed using Cohen's κ, and for continuous measurements using intraclass correlation coefficients (ICCs). The Bland-Altman plots and demographic analyses further evaluated measurement consistency. The Romanian DC/TMD Axis I showed excellent diagnostic performance, with sensitivity ranging from 85.7% (for disc displacement without reduction) to 91.2% (for myalgia), specificity of 93.5-98.2%, and AUC (the area under the receiver operating characteristic (ROC) curve) ≥ 0.91 for all diagnostic categories. Inter-examiner agreement was substantial to almost perfect (κ = 0.78-0.94), and intra-examiner agreement similarly high (κ = 0.80-0.95). Continuous mandibular measurements demonstrated excellent reproducibility (ICC = 0.89-0.96). Slightly lower sensitivity for disc displacement without reduction indicates an area for further refinement of diagnostic criteria. The Romanian version of the DC/TMD Axis I is a valid, reliable and culturally equivalent tool for diagnosing TMD. Its adoption will standardize clinical assessment, enhance interdisciplinary communication, and enable Romanian participation in multicenter and educational initiatives across Central and Eastern Europe.

Musculoskeletal ultrasonography (MSKUS) is increasingly used to assess masticatory-muscle morphology and mechanical properties, but its clinical interpretability in temporomandibular disorders (TMDs) and bruxism remains uncertain. We systematically reviewed quantitative B-mode, elastographic, functional, diagnostic, and measurement-property evidence. The final pre-submission search combined PubMed/MEDLINE, Scopus, Embase, and Web of Science Core Collection, with supplementary discovery in Europe PMC and Lens, through 20 August 2026 (PROSPERO CRD420261481058). Random-effects meta-analyses used restricted maximum likelihood (REML) with Hartung-Knapp inference. Resting masseter thickness showed no consistent case-control difference (k=14; MD -0.19 mm, 95% CI -0.78 to 0.40; I²=88.9%), nor did contracted masseter thickness (k=11; MD -0.06 mm, 95% CI -1.16 to 1.03; I²=95.9%). Anterior temporalis thickness remained inconclusive at rest (k=5; MD 0.33 mm, 95% CI -0.59 to 1.25; I²=83.4%) and during contraction (k=5; MD -0.05 mm, 95% CI -1.59 to 1.49; I²=94.5%). Resting masseter stiffness measured by shear-wave elastography remained higher in clinical/bruxism groups (k=4; Hedges' g 1.80, 95% CI 0.15 to 3.44; I²=83.5%). Certainty was very low for all pooled outcomes. MSKUS is currently better supported for adjunctive phenotyping and longitudinal monitoring than as a stand-alone diagnostic test.