[Prevalence of and its relationship with early childhood caries among children of three ethnic groups (Han, Uygur, Mongolian) in Bortala Mongol Autonomous Prefecture of Xinjiang Uygur Autonomous Region].

To investigate the distributions of (Ca), which are closely associated to early childhood caries (ECC) of young children, in 3-5-year-old children of Mongolian, Uygur and Han ethnic groups in Bortala Mongol Autonomous Prefecture of Xinjiang Urgur Autonomous Region, so as to provide scientific basis for the early prediction and prevention of caries locally. Totally 1 089 healthy children aged 3 to 5 years old (Mongolian 136, Uygur 403 and Han 550; 568 males and 521 females) were randomly selected by stratified and cluster sampling method. The children in early childhood caries group were 786 and in caries free group were 303. Dental plaque samples were collected from the carious tooth tissues and supragingival sites, respectively. Samples were isolated and cultured by different media. Ca were identified by Gram stain, germ tube test, PCR method and internal transcribed spacer region sequencing methods. Ca isolated were further typed by using PCR-25SrDNA genotype method. Pearson χ(2) test and Spearman rank correlation were used to analyze the differences in genotypes of Ca amongst three ethnic groups and the relationship between decayed missing filled tooth (dmft) classification and detection of Ca. The Ca was significantly higher in the ECC group [14.4% (113/786)] than in the caries free group [7.6% (23/303)] (0.002). The identified rate of Ca in Mongolian group was [11.8% (16/136)], which was significantly lower than that of Uygur group [17.9% (72/403)] and higher than that of Han group [8.7% (48/550)] (χ(2)=10.192, 0.006). Among the male children, the identified rate of Ca in Mongolian group was [10.0% (8/80)], which was significantly lower than that of Uygur group [21.7% (44/203)] and higher than that of Han group [8.4% (24/285)] (χ(2)=18.887, 0.000). Among the female children, the detection rates of Ca were [14.3% (8/56)] in Mongolian group, [14.0% (28/200)] in Uygur group and [9.1% (24/265)] in Han group. There were no significant differences among the three ethnic groups (χ(2)=3.206, 0.201). The identification rates of oral Ca in Uygur and Han ECC groups were correlated with the decayed, missing and filled teeth (Uygur 0.195, 0.001; Han 0.145, 0.004). Totally 136 Ca samples were divided into 3 types by PCR-25SrDNA method, and the predominant type was type A [55.1% (75/136)]. The distribution of oral Ca among children were ethnically different. Uygur male children carrying Ca were more susceptible to dental caries. Ca might be a risk factor for ECC. There was no specific cariogenic genotype in Ca isolated. There were no associations between ethnic factors and the genotypes of Ca isolated.