Dental pathology in the samurai and commoners of early modern Japan

Abstract

The class system in place during the Edo (early modern) period in Japan is thought to have included a range of customs that differed between the samurai (ruling class) and commoners. The incidence of caries in the dentition of the samurai was significantly lower than that of commoners. This difference is considered to be due to diet, eating frequency, and tooth care. As to location of the caries, it was found that the incidence of root caries in the samurai was remarkably lower than that in commoners. Root caries does not occur until gingival attachment recedes in an apical direction. The samurai and commoners did not show a significant difference in incidence of periodontal disease, while many samurai dentitions exhibited slick-polished teeth and wedge-shaped defects, which are thought to have been caused by the customary brushing of teeth. Such a custom might have successfully prevented dental caries. Given these findings, we consider that the lower incidence of caries in the samurai, compared with commoners, resulted from the influence of oral hygiene practices that helped to prevent root caries.