Researchers have identified a relationship between occlusion and brain activity. A review of 12 studies shows that changes in bite can affect the part of the brain that controls movement.
Neuroimaging techniques have shown that chewing activates parts of the somatosensory, supplementary motor, and insular cortices, but there has been little evidence for a relationship between the stomatognathic system and brain activity.
The researchers analyzed 12 relevant case-control studies, clinical trials, and systematic reviews from an online database. The findings indicate that changes in bite affect the sensorimotor cortex, which controls movement on the contralateral side of the body.
“Occlusion has been suggested to play an important role in the development of diseases ranging from anxiety and stress to Alzheimer's disease and senile dementia,” write the authors of the study, led by Sebastian Silva Ulloa of the University of Cuenca in Ecuador.
Mechanoreceptors in the periodontal ligament are one of the ways in which bite and brain function are linked. These receptors bridge the gap in communication between the teeth and the brain. At the orofacial level, mechanoreceptors perform two main functions: first, they convey information for controlling motor functions, and second, they convey information regarding the texture of food.
“Changes in the stimulation of mechanoreceptors lead to a decrease in chewing force and a lack of control over the movements of the lower jaw,” the authors of the study explained.
Chewing, in particular, is an important link between the mouth and the mind. Chewing can improve cognition and is good for memory because it activates the somatosensory cortex, accessory motor area, insular cortex, prefrontal cortex, and hippocampus.
However, previous studies have shown that “decreased chewing caused by malocclusion, loss of teeth, malprosthetics, or reduced bite force may impair cognition, including working memory, and actively manipulate stored information, thus representing a risk factor for dementia.” – the authors write.
Because chewing plays a critical role in brain health, chewing disorders are considered a risk factor for Alzheimer's disease, dementia and stress disorders. The authors noted that the latter two conditions are associated with impaired memory and learning.
Previous studies have also shown that morphological changes in the hippocampus and cell proliferation in the dentate gyrus follow the loss of molars. These changes in the hippocampus are similar to those observed with age-related changes.
Furthermore, movements during occlusion are indicative of a change in brain control after splint therapy as a treatment for mandibular clicking. Brain training induced by occlusal shields may be one of the main reasons for this, according to the researchers.
“Oral tactile stimuli would likely change in the presence of an occlusal guard, which is a foreign object inside the mouth,” the study authors wrote.
One of the key findings of this study is that dentists should consider how changes in bite during chewing can affect areas of the brain that are responsible for memory, learning, pain and anxiety.
“This suggests that chewing maintains the integrity of certain areas of the brain and that it may be a key factor in the onset of neurodegenerative diseases,” the authors concluded.