Dental Hygiene Strongly Linked to Mortality and Healthy Aging, Japanese Studies Find

Elderly patient undergoing a dental checkup highlighting the link between oral health and longevity — Good dental hygiene in old age may significantly reduce mortality and extend healthy life expectancy, Japanese studies suggest.

Poor Oral Health Linked to Higher Mortality in Older Adults

Dental health is proving to be far more than a matter of appearance or comfort. New large-scale studies from Japan suggest that oral hygiene may be a critical indicator of how long and how well people live, particularly in old age.

Researchers from Osaka Metropolitan University and the Institute of Science Tokyo have independently found strong links between poor oral health, increased mortality, and a higher risk of requiring long-term care. Together, their findings highlight dental hygiene as a key but often overlooked factor in healthy aging.

Large Osaka Study Shows Strong Connection Between Teeth and Survival

A research team led by Osaka Metropolitan University analyzed dental checkup data from 190,282 residents of Osaka Prefecture aged 75 and above, collected between fiscal years 2018 and 2020.

The study examined the relationship between dental condition and all-cause mortality and found a clear pattern:

Older adults with more healthy or treated teeth had significantly lower death rates.
Those with untreated cavities or no remaining teeth faced substantially higher risks.

According to the analysis, people with no remaining teeth had a mortality risk about 1.7 times higher than individuals with 21 or more teeth.

Researchers believe this is because untreated dental problems can impair chewing, reduce nutritional intake, and trigger chronic inflammation — all of which negatively affect overall physical health.

Healthy and Treated Teeth Prove to Be the Best Mortality Indicator

One of the study’s most notable findings was that counting healthy and treated teeth together was the most accurate predictor of mortality. This approach outperformed methods that either included untreated teeth or counted only healthy ones.

The findings, published in November in the international journal BMC Oral Health, are part of a broader epidemiological effort using real-world dental and long-term care data from Osaka Prefecture. Researchers say the results could reshape how oral health is assessed as a marker of future health risks in older adults.

Reinforcing Japan’s Long-Running “8020 Campaign”

The study builds on Japan’s well-known “8020 Campaign,” which encourages people to retain at least 20 natural teeth by age 80. Since its launch in 1989, the campaign has seen remarkable progress, with achievement rates rising from around 10% to 61.5% as of July.

“We hope that this is an opportunity to use the results of this study to help promote early treatment and regular dental care,” said Naoko Otsuki, the lecturer who led the Osaka research.

Oral Frailty Found to Shorten Healthy Life Expectancy

In a separate study, researchers at the Institute of Science Tokyo, led by Professor Jun Aida, focused on oral frailty, a decline in oral function that affects daily life.

Using nationwide data from 11,080 older adults tracked over six years, the team examined how oral health influenced transitions to disability and death.

Oral frailty was defined as having three or more symptoms, including:

Few remaining teeth
Difficulty chewing or swallowing
Dry mouth
Difficulty speaking

These conditions are known to reduce food intake, physical strength, and social interaction, accelerating health decline among older adults.

Higher Risk of Death and Long-Term Care Linked to Oral Frailty

The Tokyo study found that people with oral frailty had:

A 1.23 times higher risk of requiring long-term care
A 1.34 times higher risk of death

Healthy life expectancy at age 65 was 1.4 to 1.5 years shorter for those with oral frailty. In contrast, older adults who visited the dentist regularly enjoyed a healthy life expectancy nearly one year longer on average.