Torus mandibularis in skeletal remains from the Joseon Dynasty and modern Korea

Abstract

Torus mandibularis (TM), or mandibular tori, are nodular, excessive bony growths along the lingual side of the lower jaw. TM occurs in varying frequencies in different populations with a higher prevalence in Asiatic and circumpolar groups. The tori are associated with mechanical stress from masticatory and paramasticatory behaviors, heredity, sex, age, and environmental factors. We investigated the presence, location, symmetry, and degree of TM frequencies in two skeletal populations with cultural, biological, and geographical affinities: 15th–18th-century Joseon Dynasty Koreans (n = 119) and 20th–21st-century modern Koreans (n = 77). TM frequency is significantly higher among modern Koreans (54.6%) than Joseon Dynasty individuals (13.3%) for females and males. There are no sex differences in TM prevalence in the archaeological and modern groups and an age-related trend in the TM frequency is not observed in either sample. Our results are consistent with the literature, which reports a higher frequency in Asiatic populations, but contrary to the general worldwide trend of decreasing prevalence over time. Modern Koreans have not undergone significant dietary changes since the Joseon Dynasty, and the quasicontinuous model with external factors may be responsible for the development of TM.