Identification And Gene Polymorphism For Main Streptococci In The Dental Plaques From Children's Rampant Caries

Objective:To investigate the pathogenic bacteria, Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus), from rampant caries of children and study genotypes of S. mutans, to provide scientific bases for its prevent Methods Biochem Anal.Methods:Isolating pathogens from rampant caries of children, identifying them using bacteriological and molecμlar biological methods. According to the examination of SPSS10.0χ2, the difference of the detectable rate of S. mutans and S. sobrinus from dental piaque.Analyzing the relationship of the occurrence of rampant caries with the polymorphism of S. mutans (serotype C) by means of Arbitrarily Primed Polymerase Chain Reaction(AP-PCR). The number of genotype of S. mutan according to the examination of SPSS10.0 One-Way Anaalysis of Variance(ANOV).Also analyzing the relevance between the detectable rates of S. sobrinus from dental caries and the number of genotype of S. mutans, via SPSS10.0 Univariate ANOV, in order to deduce their relationship with rampant caries of children.Resμlts:A total number of 20 strains were isolated from 66 individuals with dental caries, among which 752 clinical isolates of S. mutans(serotype C) and 66 clinical isolates of S. sobrinus were identified. According to the examination, the difference of the detectable rate of S. mutans between rampant caries group and caries susceptible(CS) in deciduous teeth group is not significant statistically (P=0.206 >0.05); the difference of the detetable rate of S. sobrinus is significant (P=0.033< 0.05); the difference of the detectable rate of S. mutans between rampant caries group and caries free(CF) group is significant statistically (P=0.031<0.05); the difference of the detectable rate of S. sobrinus is significant(P=0.005<0.01). According to the AP-PCR to S. mutans (serotype C) among children:The genotype of S. mutans (serotype C) among children with dental caries is polymorphic; According to the examination, the average number of genotype of the clinical isolates of S. mutans (serotype C) in children with rampant caries is higher than control group and this difference is significant statistically (F=4.08, P=0.024< 0.05); the average number of genotype of S. mutans in children that carry S. sobrinus is different from those do not carry S. sobrinus and this difference is significant statistically (F=8.743, P=0.005).Conclusion:The bacteria that cause rampant caries in children include S. mutans and S. sobrinus, among which S. sobrinus has a higher isolation rate and typing of S. mutans (serotype C) in clinical isolates shows its polymorphism nature. S. mutans(serotype C) in children with rampant caries have more genotypes than in children with caries free. The isolation of S. sobrinus and gene polymorphism of S. mutans (serotype C) shows positive relationship with rampant caries in children.