Abstract— The role of the occlusion in the aetiology of reflex jaw muscle hyperactivity and myofacial pain is analysed. Neurological mechanisms are proposed to explain how variations in occlusal morphology of sufficient magnitude (segmental influences), and the presence of anxiety states (suprasegmental influences) affect jaw muscle activity and contribute to myofascial pain. Controlled occlusal therapy may alter the segmental neurological control of jaw muscle activity to facilitate resolution of muscle hyperactivity in acute myofascial pain. Chronic myofascial pain dysfunction is not primarily related to occlusal factors and a complex psychophysiological mechanism is involved in this type of pain problem.