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Poor dental hygiene is directly linked to decrease in brain volume and mental decline

A recently published study adds a compelling reason to maintain your dental hygiene: It might be linked to the health of your brain and mental decline.

The study, which appeared in the online July 5, 2023 issue of Neurology, the medical journal of the American Academy of Neurology, investigates the potential connection between brain health and dental health.

The research identified that common dental issues, like gum disease and tooth loss, could be related to shrinkage in the hippocampus, a part of the brain involved with memory and Alzheimer’s disease.

It’s crucial to note that the study doesn’t claim that these dental problems cause Alzheimer’s disease. However, it has certainly shown a strong association.

Satoshi Yamaguchi, PhD, DDS, the author of the study from Tohoku University in Sendai, Japan, explained the significance of the findings.

“Tooth loss and gum disease are very common, so evaluating a potential link with dementia is incredibly important,” said Yamaguchi. He added, “Our study found that these conditions may play a role in the health of the brain area that controls thinking and memory, giving people another reason to take better care of their teeth.”

How the dental hygiene study was conducted

The study engaged 172 participants, all around the age of 67, and none of them reported memory problems at the study’s outset. All underwent dental exams and memory tests. Their hippocampal volume was measured via brain scans at the beginning of the study and again four years later.

Researchers assessed the dental hygiene and health of the participants by counting their teeth and measuring the depth of their gum tissue, a key indicator of gum disease. Healthy gums typically measure between one and three millimeters deep.

Mild gum disease is signified by measurements of three to four millimeters in several areas, while severe gum disease involves measurements of five to six millimeters, accompanied by more bone loss, leading to loose teeth and potential tooth loss.

What the scientists discovered

The research found a link between the number of teeth and the severity of gum disease to changes in the left hippocampus of the participants’ brains.

Interestingly, in people with mild gum disease, fewer teeth correlated with mental decline from faster shrinkage in the left hippocampus. Conversely, in those with severe gum disease, more teeth were associated with faster shrinkage in the same area.

In terms of brain aging, researchers found that for individuals with mild gum disease, each lost tooth accelerated the rate of brain shrinkage, equivalent to nearly one year of brain aging. However, for those with severe gum disease, each additional tooth corresponded to a faster rate of brain shrinkage, equivalent to 1.3 years of brain aging.

Yamaguchi emphasized the implications of these findings. “These results highlight the importance of preserving the health of the teeth and not just retaining the teeth,” he stated.

Poor dental hygiene and gum disease linked to mental decline

The study’s results suggest that keeping teeth suffering from severe gum disease might be linked to brain atrophy. Yamaguchi underscored the importance of regular dental check-ups to control gum disease progression. Teeth severely affected by gum disease might need to be extracted and replaced with suitable prosthetic devices.

As promising as these findings are, Yamaguchi admits that more research is needed, preferably involving larger groups of participants. He also noted the study’s geographical limitation, as it was conducted only in one region of Japan, and therefore the results may not be applicable to other populations.

The research was funded by multiple Japanese institutions, including the Ministry of Education, Culture, Sports, Science and Technology; Keio University; Japan Arteriosclerosis Prevention Fund; Ministry of Health, Labor, and Welfare; Teikyo University; and various pharmaceutical companies and foundations.

In essence, this study shows that taking care of your teeth goes beyond just maintaining a bright smile. It might also be a significant factor in preserving your brain health.

Practicing good dental hygiene will potentially prevent mental decline by helping to ward off diseases like Alzheimer’s. So, make sure to keep up with your dental hygiene and routine check-ups; your brain might thank you for it.

More about dental hygiene

Dental hygiene, also known as oral hygiene, refers to the practice of keeping the mouth and teeth clean to prevent dental problems like cavities, gum diseases, and bad breath.

Good dental hygiene is essential for overall health. Research has linked poor oral health to a variety of conditions such as heart disease, diabetes, and Alzheimer’s. Here are some important aspects to consider:


This is the cornerstone of good dental hygiene. You should brush your teeth at least twice a day. Ideally in the morning and before bed, using a soft-bristle toothbrush and fluoride toothpaste.

The toothbrush should be held at a 45-degree angle to the gums. Brushing should cover all surfaces of the teeth, using gentle, circular motions. Brushing your tongue is also crucial, as it can harbor bacteria and contribute to bad breath. Remember to replace your toothbrush every three to four months, or sooner if the bristles are frayed.


Flossing removes food particles and plaque that your toothbrush can’t reach. It should be done once a day, usually before bed. To floss correctly, you should use an 18-inch piece of floss. Wind most of it around your middle fingers, and then gently glide it between the teeth, following the curve of each tooth to avoid damaging the gums.


After brushing and flossing, rinsing your mouth with water or mouthwash helps to remove any lingering particles. Some mouthwashes also contain ingredients to fight bacteria and freshen breath.


Consuming a balanced diet can contribute to good dental health. Try to limit sugary foods and drinks, as sugar promotes the growth of the bacteria that cause cavities. Foods high in calcium and phosphorus, like milk, cheese, and lean meats, can help to keep your teeth strong.

Regular Dental Visits

Regular check-ups and cleanings by a dental professional are essential, usually every six months. Although the frequency may vary based on your individual dental health. These visits can help detect problems early, when they’re easier and less expensive to treat. They can also remove tartar, a hardened form of plaque that can’t be removed by normal brushing and flossing.

Avoiding Tobacco

Tobacco, in both smoked and smokeless forms, can lead to gum disease, tooth discoloration, bad breath, and oral cancer. Quitting tobacco use can significantly reduce these risks.

Remember, dental hygiene is not just about having a beautiful smile; it’s an important part of your overall health. Practice good oral hygiene habits daily, and your teeth and body will thank you.

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