title: Dental and periodontal status of 12-year-old Dai school children in Yunnan Province, China: a cross-sectional study.
abstract: BACKGROUND
  The Dai people are one of the ethnic minorities in China and have a population of 1,260,000. They have the same origin as one of the main ethnic groups in Laos and Thailand. The study aims to describe the dental caries and gingival status of 12-year-old Dai children in China and to study the factors affecting their oral-health status.
  
  
  METHODS
  This cross-sectional oral-health survey was conducted from 2011-2012 with ethics approval. A sample of 12-year-old Dai children living in Yunnan, China, was selected using a multistage and cluster sampling method. One trained examiner performed the clinical examination. Caries experience was measured using DMFT index, and gingival status was assessed with CPI index. A self-completed questionnaire was sent to the children, and they were asked about their backgrounds and oral-health-related behaviors and oral-health knowledge. Binary logistic regression analysis was performed to investigate the factors that affected the caries status.
  
  
  RESULTS
  A total of 875 children were invited, and 823 (94 %) joined the survey. The prevalence of caries experience among the participants was 40 %. The mean DMFT and DT scores were 0.9 and 0.8, respectively. Most children (93 %) had gingivitis, and many (46 %) had calculus. Girls and those who had visited a dentist during the previous year had a higher prevalence of caries.
  
  
  CONCLUSIONS
  Dental caries were prevalent among 12-year-old Dai children in China. The periodontal condition of most of the children was poor. Caries were associated with gender and dental attendance.
authors.affiliation: Faculty of Stomatology, Kunming Medical University, Yunnan, China. snzhang2000@163.com.
authors.forename: Shinan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Faculty of Stomatology, Kunming Medical University, Yunnan, China. xubiao1962@163.com.
authors.forename: Biao
authors.initials: B
authors.lastname: Xu
authors.affiliation: Faculty of Stomatology, Kunming Medical University, Yunnan, China. liujuan1966@yahoo.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Liu
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China. hrdplcm@hku.hk.
authors.forename: Edward Cm
authors.initials: EC
authors.lastname: Lo
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China. chchu@hku.hk.
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Chu
mesh_terms: D002648:Child; D002681:China; D003430:Cross-Sectional Studies; D003731:Dental Caries / Q000453:epidemiology; D003753:Dental Health Surveys; D005260:Female; D005882:Gingival Diseases / Q000453:epidemiology; D006801:Humans; D008297:Male; D008913:Minority Groups; D009909:Oral Health; D010510:Periodontal Diseases / Q000453:epidemiology; D015995:Prevalence