Variability of Exostoses on Human Jaws During the Past Six Millennia in Northern China

Abstract

The aim of this study was to survey oral exostoses in human populations that belonged to the same region encompassing five periods over 6000 years, to determine the prevalence and its changing trend over time. A total of 306 human jaws belonging to the modern Xi'an region and four archeological sites, Banpo (6700-5600 years BP), Shaolingyuan (3000 years BP), Shanren (2200 years BP) and Chang'an (1000-1300 years BP), were investigated. The degree of buccal exostosis (BE), torus mandibularis (TM) and torus palatinus (TP) and the TP shape were recorded. The prevalence of BE, TM, and TP in the five groups was 20.8 %-62.5 %, 17.5 %-71.5 %, and 31.7 %-74.2 %, respectively. The differences in the three types of exostoses among the five groups were all statistically significant, but only TM and TP showed a decreasing trend over time. A high and quite diverse prevalence of oral exostoses was found in the five groups of samples. Decreasing trends in relation to time for TM and TP were detected.

Prevalence of Oral Exostoses in Northern China During the Past Six Millennia—From a Sex and Age Perspective

“…In a sample of 306 jaws studied, 213 BEs, 226 TMs, and 116 TPs were identified. The extent of the 3 types of exostoses and the distribution of TP morphology in different populations were described previously 16…”

“…The detailed morphological observations of samples have been described in our previous work. 16 Briefly, BEs, located buccally of maxillary molar regions, were typically continuous bony ridges of wavy shape (Fig. 3A) or uniform thickness (Fig.…”

“…The extent of the 3 types of exostoses and the distribution of TP morphology in different populations were described previously. 16 The Prevalence of Oral Exostoses Concerning Sex in Each Period Supplementary Digital Content Tables 2 and 3 (http:// links.lww.com/SCS/E461) shows the distribution of oral exostoses according to sex. In the Banpo samples, BEs were more often diagnosed in males, whereas a severe degree was only observed in females.…”

“…Similarly, many researchers have reported a positive correlation between exostoses and age,9,13 but a number of studies provide contradictory results 14,15. In contrast, previous literature has revealed that, as nonmetric traits of the jaw, oral exostoses have a particular trend of transformation over time 16…”

“…14,15 In contrast, previous literature has revealed that, as nonmetric traits of the jaw, oral exostoses have a particular trend of transformation over time. 16 Although there have been some studies on the sex and age differences in the incidence of oral exostoses, few have investigated samples from one site spanning several chronological ranges on this aspect. Our previous study collected relatively intact jaws from 4 ancient and modern populations in Xi'an, China, the ancient capital of 6 dynasties, an imperative historical city located in the north of China (Fig.…”