Novel stress increases hypothalamic-pituitary-adrenal activity in mice with a raised bite.

Background And Objective: In humans, occlusal disharmony may cause various physical complaints, including head and neck ache, stiffness in the shoulder and neck, and arthrosis of the temporomandibular joints. Occlusal disharmony induced by raising the bite in rodents, increases plasma corticosterone levels, which leads to morphologic changes in the hippocampus and altered hippocampus-related behavior. The paraventricular nucleus (PVN) of the hypothalamus regulates the hypothalamic-pituitary-adrenal system.

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.

Effect of bite-raised condition on the hippocampal cholinergic system of aged SAMP8 mice.

Occlusal disharmony induces chronic stress, which results in learning deficits in association with the morphologic changes in the hippocampus, e.g., neuronal degeneration and increased hypertrophied glial fibrillary acidic protein-positive cells.

Masticatory function and cognitive function.

Recent studies have suggest that masticatory (chewing) function is useful for maintaining neurocognitive function in the elderly. For example, a reduced ability to masticate, such as that resulting from toothlessness or soft-diet feeding, causes learning and memory deficits in aged animals and pathologic changes in the hippocampus. In addition, occlusal disharmony impairs hippocampal memory processes via chronic stress, and induces similar hippocampal pathology.