Etiological Roles Are Not Fixed: A Functional–Temporal and Adaptive-Capacity Framework for Painful Temporomandibular Disorders

Background/Objectives: Painful temporomandibular disorders (TMDs) are multifactorial and biopsychosocial, yet identifying associated factors does not establish the function each factor occupies along an individual clinical trajectory. This conceptual hypothesis article aimed to propose a functional–temporal framework that distinguishes etiological role from biopsychosocial domain and incorporates individual adaptive capacity. Methods: The framework was developed from established TMD concepts and purposively selected prospective and longitudinal evidence relevant to first onset, post-onset course, repeated measurement, and person-by-exposure interaction. The article is not a systematic or scoping review. Results: Recognized influences are organized into three functional positions: predisposing, initiating, and perpetuating. These positions are not treated as intrinsic properties of variables; assignment depends on temporal ordering, context, measurement, phenotype, and the specified outcome. Adaptive capacity is proposed as a conceptual source of differential response and is distinguished from generic effect modification, which is one empirical strategy for testing the hypothesis. Existing longitudinal studies show that susceptibility, onset-related change, post-onset course, and exposure-by-person interactions can be measured, but no cohort has validated the complete framework. Falsifiable predictions and conservative wording rules are specified. Conclusions: The framework offers a temporally disciplined approach to etiological interpretation and patient communication without implying deterministic causation or treatment efficacy. Its current empirical basis is strongest for painful TMD, and densely measured inception cohorts are needed to test whether functional position and prespecified moderators add explanatory or predictive information.