Clinical, Psychosocial, and Somatosensory Differences Between Bruxers with and without Painful Temporomandibular Disorders.

OBJECTIVES: This study compared psychosocial, clinical-health, and somatosensory parameters between participants with subject-based and/or clinically based indications of bruxism with and without temporomandibular disorder (TMD). Additionally, the associations between the Central Sensitization Inventory (CSI), quantitative somatosensory testing (QST) parameters, and characteristic pain intensity (CPI) were investigated. METHODS: A cross-sectional clinical study included 68 participants allocated into two groups: bruxers without painful TMD (Brux-TMDPain, n = 14) and bruxers with painful TMD (Brux+TMDPain, n = 54). Psychosocial measures included the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder Scale-7 (GAD-7), and Pain Catastrophizing Scale (PCS). Clinical-health variables comprised the Jaw Functional Limitation Scale (JFLS), Pittsburgh Sleep Quality Index (PSQI), and CPI. Somatosensory parameters included the CSI and QST measures: pressure pain threshold (PPT), wind-up ratio (WUR), and conditioned pain modulation (CPM). Mann-Whitney U and chi-square tests were used for between-group comparisons. Associations between CSI, QST, and CPI were analyzed using Spearman's correlation, with additional subgroup analyses based on CSI scores (≥40 vs. < 40). RESULTS: Compared with Brux-TMDPain, Brux+TMDPain showed significantly lower PPTs at the masseter (1483 vs. 1797 g/f; p = 0.03) and TMJ (1681 vs. 2202 g/f; p = 0.03), and higher scores for CPI (50.0 vs. 21.5; p = 0.002), PHQ-9 (p = 0.04), GAD-7 (p = 0.05), PCS (p = 0.01), and JFLS (p = 0.003). CSI correlated negatively with PPTs (ρ = -0.43 to -0.50; p ≤ 0.01) and positively with WUR (ρ = 0.37; p = 0.009). In Brux+TMDPain, higher CSI scores were associated with higher CPI (ρ = 0.30; p = 0.03). CONCLUSION: Bruxers with painful TMD exhibited indications of greater peripheral hyperalgesia, psychosocial burden, and mandibular functional limitation. CSI scores did not distinguish participants with and without painful TMD, although their modest association with pain intensity suggests a dimensional relationship with self-reported symptom burden. These findings support integrated, multimodal assessment within a biopsychosocial framework to better characterize phenotypic profiles and inform individualized clinical strategies. CLINICAL SIGNIFICANCE: Simple muscle overloading alone may not sufficiently explain the pathophysiology of TMD pain, as alterations in somatosensory processing and central sensitization-related features may also contribute.