Objective  To evaluate the oral health status of the 12-year-old population in Hainan province, and provide information supporting oral health care.

  Methods  From December 2015 to June 2016, 12-year-old residents in urban and rural areas of Hainan province were selected by the method of multi-stage stratified random sampling of equal capacity. According to the program of the fourth national epidemiological survey of oral health, dental caries and periodontal conditions of permanent crowns in the whole mouth were examined by dental mirror and community periodontal index probe. The rate of caries prevalence, the mean decayed-missing-filled teeth (DMFT), the rate of filling, the rate of pit and fissure sealing, the rate of gingival bleeding and the rate of dental calculus detection were calculated.

  Results  A total of 595 children, 297 males and 298 females, aged 12, in Hainan province were examined in this study, 358 of them from urban areas and 237 from rural areas. All of them are middle school students. The rate of caries prevalence was 57.0% (339/595), the mean DMFT was 1.71 (1020/595), the rate of filling was 13.6% (139/1019), the rate of pit and fissure sealing was 1.5% (9/595), the rate of gingival bleeding was 46.9% (279/595), and the rate of dental calculus detection was 39.5% (235/595). The proportion of caries from the highest to the lowest were the left lower first molar (18.4%), the right lower first molar (18.1%), the left upper central incisor (7.8%), the right upper first molar (7.7%), the right upper central incisor (7.6%), and the left upper first molar (7.3%). The rate of caries prevalence (63.3% vs. 52.8%, P=0.011) and mean DMFT (2.04 vs. 1.50, P=0.008) of rural children were higher than those of urban children. The rate of gingival bleeding (40.9% vs. 50.8%, P=0.018) of rural children was lower than that of urban children. There were no significant differences in the rate of filling (12.0% vs. 15.1%, P=0.143), the rate of pit and fissure sealing (0.4% vs. 2.2%, P=0.076) and the rate of dental calculus detection (35.4% vs. 42.2%, P=0.100) between the rural children and the urban children. The rate of caries prevalence of male children (52.9% vs. 61.1%, P=0.043) was lower than that of female children. The rate of filling (16.7% vs. 11.2%, P=0.011) and the rate of gingival bleeding (52.9% vs. 40.9%, P=0.004) of male children were higher than those of female children. There were no significant differences in the mean DMFT (1.54 vs. 1.89, P=0.061), the rate of pit and fissure sealing (1.3% vs. 1.7%, P=0.741), and the rate of dental calculus detection (41.1% vs. 37.9%, P=0.431) between the male children and the female children.

  Conclusions  The prevalence of permanent teeth caries in the 12-year-old population in Hainan province was high. Most of the decayed teeth were not filled. And the sealant rate of pits and ditches was low. Their periodontal health was poor. Targeted oral health measures should be further developed in the light of the urban-rural and gender differences.