The Distribution Of Streptococcus Mutans And Its Relationship With Early Childhood Caries In Three Minority Children In Bortala Region Of Xinjiang Province

Objective:To investigate the detection rate of Streptococcus mutans(S.mutans)in children aged 3~5 years old in Bortala Region of Xinjiang province,included Han,Uygur and Mongolian.Then the correlation between genotypic diversity of S.mutans and dental caries in preschool children was analyzed.Methods:In accordance with the inclusion and exclusion criteria,the plaque samples of 90 subjects were randomly selected from the epidemiological investigation of Bortala Region of Xinjiang province.These samples were divided into severe early childhood caries(S-ECC)group(n=45)and caries-free(CF)group(n=45),an average of 15 people in Han,Uygur,Mongolian.The plaque samples were collected and cultured with Mitis-Salivarius-Bacitrac in Agar and Brain Heart Infusion.S.mutans were further identified by Gram staining,biochemical identification and polymerase chain reaction(PCR).Arbitrarily Primed PCR(AP-PCR)fingerprinting was applied in the genotypes distribution of S.mutans.Results:The detection rate of S.mutans was 75.5%,and the detection rate of S.mutans in S-ECC group was 86.7%,which was higher than that in CF group(64.4%).The difference was statistically significant(P=0.014).The detection rate of S.mutans was not different among the three ethnic groups(P=0.457).After isolation and identification,a total of 549 clinical strains of S.mutans were obtained and 113 different genotypes were obtained.Individuals carrying more than one S.mutans genotype in the S-ECC group accounted for 61.5%,and individuals in the CF group carrying more than one S.mutans genotype accounted for 37.9%.The genotypic diversity of S.mutans in S-ECC group of three ethnic groups was higher than that of CF group,the difference was statistically significant(P=0.035).The results of the trend chi-square test showed that there was a linear correlation between the genotypic diversity in Han,Uygur,Mongolian and decayed-missing-filled tooth(?~2=4.767,P=0.029).Conclusion:The distribution of S.mutans in children's oral cavity in Bozhou area was significantly different among different caries sensitive groups.There was no difference among ethnic groups.The S-ECC group had more genotypes than the CF group,and the number of genotypes might be related to the carious ability of S.mutans.