A recent study finds that people with fewer natural teeth perform poorly on memory tests.
Looking at 273 people ages 55 and older, the researchers found a modest but significant relationship between a person's number of natural teeth and his or her performance on memory tests, Fox News reported.
The link held when researchers took subjects' ages into account. In other words, it wasn't simply that both teeth and memory abilities tend to disappear with age.
Although the reason for the link isn't entirely clear, the new findings are in line with previous animal and human studies, suggesting that the presence of natural teeth has an impact on cognitive function, and having fewer teeth may be regarded as a risk factor for memory problems in the elderly, according to the researchers.
Animal studies have shown that rats whose teeth were pulled out showed memory and learning problems. The rats that had lost more teeth showed higher neuronal loss, and more damage to the hippocampus, a part of the brain involved in memory formation.
It is possible that loosing natural teeth reduces sensory signals that teeth send to the brain, affecting its functions, including memory, the researchers said.
Natural teeth send signals to the brain via a nerve that is responsible for sensation in the face, and for motor functions, such as biting and chewing.
Prosthetic teeth, though helpful for eating, lack the nerves and ligament that attach natural teeth to the jaw, potentially resulting in a reduced sensory input to the brain.
It's also possible that a common factor could be responsible for the link between teeth and memory.
For instance, gum infections that could lead to tooth loss may also cause inflammation, which may, in turn, cause neuronal death and memory loss, the researchers said.
The findings are published in the European Journal of Oral Sciences.