Over the past 70 years, temporomandibular joint (TMJ) diseases have been subjected to shifts in conceptual understanding. Unable to account for disease patterns, the mismatch between case assignment and treatment need, and different interventions producing similar treatment outcomes (although at varying levels of risks to patients), emerging theories make persuasive arguments in support of alternative explanations that conceptualize TMJ diseases as complex conditions influenced by genetic susceptibility, environmental factors and risk-conferring behaviors.