title: [Study on periodontal disease in Chinese in Xia Dynasty].
abstract: OBJECTIVE
  To study the teeth of the ancients in Xia Dynasty, the first dynasty in Chinese history about 4 000 years ago, and acquaint ourselves with their incidences of periodontal disease,and the evolution of oral diseases.
  
  
  METHODS
  The teeth and jaws excavated in Erlitoou, Henan Province and Youyao, Shanxi Province were observed with clinical methods. The specimens totaled 56 individuals (male 38, and female 18), including 894 teeth, and 86 dental arches. The objects were all permanent teeth. The major observation items were periodontal disease. The prevalence of periodontal disease of the people in Chinese Xia Dynasty were outlined.
  
  
  RESULTS
  The prevalence rate of periodontal disease was 19.80% in the 894 teeth, while prevalence rate was about 42.86% among the individuals. The premortal tooth loss rate was 7.45% in the observed teeth.
  
  
  CONCLUSIONS
  Periodontal disease is an age-related disease without sex difference and commonly seen in the mandible, which is quite similar to the situation at present. The periodontal disease was the main reason for tooth loss in people of Xia Dynasty.
authors.affiliation: Department of Orthodontics, Peking University School & Hospital of Stomatology, Beijing 100081, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Xiang-long
authors.initials: XL
authors.lastname: Zeng
authors.forename: Wu
authors.initials: W
authors.lastname: Liu
mesh_terms: D044466:Asian People; D005260:Female; D049690:History, Ancient; D006801:Humans; D008297:Male; D010510:Periodontal Diseases / Q000453:epidemiology* / Q000266:history*; D015995:Prevalence