Four‐Dimensional Impact of Oral Behaviours on Oral Health‐Related Quality of Life Across <scp>TMD</scp> Subtypes: A Parallel Multivariate Exploration

BACKGROUND: Temporomandibular disorders (TMDs) impair oral health-related quality of life (OHRQoL) through pain, dysfunction and psychosocial distress. Oral behaviours may exacerbate these impacts, but their associations across TMD subtypes remain underexplored. OBJECTIVES: This study examined oral behaviours across TMD subtypes and their relationships with psychological distress, alongside their four-dimensional impacts on OHRQoL. METHODS: A total of 989 first-visit TMD patients (mean age 29.7 years [SD 10.6]; 80.6% female) completed the Oral Behaviour Checklist, Patient Health Questionnaire-9, General Anxiety Disorder-7 and Oral Health Impact Profile for TMDs. Diagnoses followed DC/TMD protocol, classifying participants into intra-articular (IT: 28.9%), pain-related (PT: 38.4%) and combined (CT: 32.7%) TMD subtypes. Jaw overuse behaviour (JOB) was categorised as normal (NO: 18.6%), low (LO: 29.4%) or high (HO: 52.0%). Analyses included nonparametric tests, Spearman correlations and logistic regressions (α = 0.05). RESULTS: CT and PT reported more frequent waking-state nonfunctional oral activities (WN), higher psychological distress and poorer OHRQoL than IT. HO showed significantly greater impairment across all four OHRQoL dimensions: oral function, orofacial pain, orofacial appearance and psychosocial impact. Appearance and function consistently ranked highest among dimensions. Depression and anxiety were moderately correlated with psychosocial impact (rs = 0.51-0.65). High JOB was associated with younger age (OR 0.95), higher education (ORs 2.01-2.59) and depression (OR 1.07). Low OHRQoL was linked to female sex (OR 1.67), older age (OR 1.03), PT/CT subtypes (ORs 2.49-3.60), WN (OR 1.16) and anxiety (OR 1.29). CONCLUSIONS: Oral behaviours, especially WN, are significantly associated with psychological distress and multidimensional OHRQoL impairment in TMD patients, with distinct patterns across diagnostic subtypes.