Occlusal disharmony affects plasma corticosterone and hypothalamic noradrenaline release in rats

Few neuro-endocrinological studies have examined the relationship between occlusal disharmony and stress. To determine the effect of occlusal disharmony on the central nervous system, we measured plasma corticosterone and extracellular noradrenaline in the vicinity of the hypothalamic paraventricular nucleus in rats both with and without incisal caps. After the caps were set, plasma corticosterone and extracellular noradrenaline levels gradually increased, reaching a peak at 8.5 and 6.5 hours, respectively, after which they decreased. Furthermore, plasma corticosterone and extracellular noradrenaline levels increased in a circadian fashion around the onset of the dark phase in rats without caps, but not in rats with caps. These results suggest that occlusal disharmony causes chronic stress in the rat.