Prevalence of dental fluorosis of children aged 8-12 in coal-burning type of endemic fluorosis areas in Guizhou Province

Objective To investigate the prevalence of dental fluorosis of children aged 8 - 12 in coal-burning type of endemic fluorosis areas in Guizhou Province and to provide a scientific basis for assessment and acceptance of the diseased areas. Methods According to the "Diagnosis of Dental Fluorosis" (WS/T 208-2011), dental fluorosis of all children aged 8-12 were examined in historic diseased areas of 13 counties (districts) from 2013 to 2014. The date of dental fluorosis of all children aged 8-12 was collected in 13 countries (districts) in 1986 and 2000. The date of 1986 was compared with that of 2000; the survey results were compared with those of 2000, and assessed by the standards for "Control Criteria for Endemic Fluorosis Areas" and "Elimination of Coal-burning Type of Endemic Fluorosis". Results The total detectable rate of dental fluorosis of children aged 8 - 12 was 5.42% (12 446/229 428), and the total dental fluorosis index was 0.094 that covered 229 428 children from 1 673 villages of 166 towns of 13 counties (districts) in the province. The detection rate and dental fluorosis index in every county (district) ranged from 2.83% to 9.39% and from 0.037 to 0.174, respectively. The ratio of dental fluorosis detection rate ≤15% and > 15 - 30% was accounted for 98.09% (1 641/1 673) and 1.91% (32/1 673), respectively in the 1 673 villages. Compared with that of 2000 in each county (district), the difference was statistically significant (all P 0.05), but the prevalence was significantly lower in Huishui County, Wudang District and Huaxi District (χ2 = 537.70, 352.03, 374.84, all P < 0.01). The prevalence was increased to varying degrees in counties (districts) including Honghuagang, Zhenning, Changshun, Pingba, Longli, Xifeng and Kaiyang (χ2 = 9.48, 219.97, 116.93, 288.24, 626.39, 272.38, 14.35, all P < 0.01). Conclusions The detection rate of dental fluorosis of children aged 8 - 12 is significantly dropped and lower than 10%. All surveyed countries are up to the standards of elimination except Pingba, where 32 villages are in a level of control. It's recommended that comprehensive assessment should be carried out with relevant health standard in endemic fluorosis areas. Key words: Fluorosis, dental; Coal; Endemic diseases; Data collection