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 checkups 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.

In Japan, domiciliary care fees are only covered by the public health insurance system if the clinic concerned is located within 16 km of the patient's residence. This nationwide rule does not take local conditions into account and therefore may not be appropriate. The goal of the present study was to assess the current state of domiciliary dental care nationwide in view of this restriction to clarify the current situation and any inherent problems. Six dental institutions providing domiciliary dental care were selected by location (urban or mountainous area) and size. Travel time from clinics to the 16 km points and the longest time required for the journey from clinics were investigated. Two of the dental clinics were located in depopulated areas with few dental institutions. These clinics had to provide domiciliary dental care not only in the 16-km area around the clinic, but also in areas over 16 km away. Travel time to the 16-km points was between 52 and 90 min. On the other hand, the longest time for actual visiting was between 30 and 60 min. In some areas, no domiciliary dental care was available within the 16 km limit. This indicates that the 16-km area is too wide to be covered by one dental institution alone and that it poses a problem in areas with few dental institutions. This suggests that it would be preferable to consider time required to visit rather than geographical distance in forming policy. The 16-km limit often spans multiple residential areas, indicating that greater coordination is needed between the Community-based Integrated Care System and dental offices.