How to Increase Number of Present Teeth in Elderly: Consideration of Percentile Curves for Present Teeth in Tokyo

Maintaining dental and oral health and increasing healthy life expectancy are important issues for Japan as it deals with the rapid aging of its population. The purpose of this study was to determine effective dental health measures aimed at increasing the number of present teeth in the elderly. Change in the number of present teeth was determined based on data obtained from the 2009 and 2014 "Good Teeth Tokyo (Ii-ha Tokyo)" surveys carried out by the Tokyo Metropolitan Government. The number of present teeth and percentile curves were compared between these two time points. The number only showed a significant increase in individuals aged 60 years in 2014 (p<0.05). This may have been due to the establishment of a national public insurance system. The number of present teeth showed an increase in 2014 in the 25th, 50th, and 75th percentile curves. In the 75th and 90th percentile curves, tooth loss accelerated when the number of present teeth was fewer than 25. This finding is consistent with studies reporting that tooth loss itself is a risk for tooth loss. Tooth loss showed a slight acceleration between the ages of approximately 20 and 45 years in the 90th percentile curve. These results indicate that dental check-ups at universities and companies, periodontal disease check-ups performed by local governments, and health instruction at these check-ups are necessary to increase the number of present teeth in the elderly. They further suggest that implementing measures to promote periodic visits to dental clinics and providing incentives to undergo treatment for tooth defects are necessary in high-risk individuals. In conclusion, dental check-ups, health instruction, and strategies for high-risk individuals in their 20s and 40s are necessary to increase the number of present teeth in the elderly.