The number of missing teeth in people of the Edo period in Japan in the 17th to 19th centuries.

OBJECTIVE

The aims of this study were to examine the number of missing teeth in the people of the Edo period (or number of remaining teeth) and to contribute to the 8020 movement proposed in Japan to help people retain 20 or more of their own teeth until the age of 80.

BACKGROUND

The study of dentition in ancient skeletal remains of our ancestors from multiple perspectives can yield information that can contribute to the study of physical anthropology and the leading edge of modern dental research.

MATERIALS AND METHODS

The materials were 82 excavated individuals (52 males and 30 females) from 1603 to 1868 whose maxillas and mandibles were both examinable. The age and sex were estimated by anthropological methods, and the individuals were divided into five groups. The status of missing teeth was compared between groups, and a chi-square test was used to test significant differences between groups. The rates of tooth loss were examined in the maxillas and mandibles.

RESULTS

In the people of the Edo period, many teeth remained in good condition until early to late middle age. There were more remaining teeth in these individuals than in modern-day individuals. However, the Edo people clearly showed increased tooth loss with age. There were no differences in tooth loss by sex. The tooth type with a high rate of tooth loss was posterior teeth, but incisor loss also occurred with ageing. Mandibular canines were most likely to be remaining.

CONCLUSION

The Edo people had more remaining teeth than modern-day society. This finding was unexpected. The notion that "people of long past ages lost more teeth more quickly" does not seem to apply to people in the Edo period in Japan.