Occlusal disharmony leads to learning deficits associated with decreased cellular proliferation in the hippocampal dentate gyrus of SAMP8 mice.

Occlusal disharmony is associated with increased plasma corticosterone levels, learning deficits, and morphologic alterations in the hippocampus via chronic stress. Here, we investigated the occlusal disharmony-induced impairment of hippocampal function. We first examined the effects of raising the bite on newborn cell proliferation in the hippocampal dentate gyrus (DG) in senescence-accelerated prone mice. Raising the bite significantly decreased cell proliferation in the hippocampal DG in an age-dependent manner. Immediately after raising the bite, cell proliferation decreased abruptly in the aged mice, then gradually increased, but did not recover to control levels within 2wk. Further, learning-induced cell proliferation was impaired in aged bite-raised mice. These findings suggest that occlusal disharmony induced by raising the bite impaired cell proliferation in the hippocampal DG, leading to learning deficits.