Background: Streptococcus mutans and Streptococcus sobrinus are major pathogens causing Early Childhood Caries. The experience of caries in children is associate with mother’s caries experience and the acquisition and transmission of this strain in various populations have received extensive attention. Objective: the aim of this study was to use a simple and rapid molecular method named Polymerase Chain Reaction (AP-PCR) to verify the transmission and genotypic concordance of Streptococcus sobrinus in mother child (0-36months) pairs. 
 

Materials and methods: A hundred one of mother-child pairs were evaluated. Plaque samples were taken in both mother and child with a cotton swab each one. Mothers completed a questionnaire regarding their sociodemographical behaviors and dental behaviors. Detection of Streptocccus sobrinus ATCC® 33402TM was performed by AP-PCR. Group mean values were compared using Pearson Chi-Square and Fisher’s Exact Test. (IBM SPSS 22.0, Chicago, Illinois, USA). 
 

Results: The results showed 16 mother-child pairs (15.8%) had Streptocccus sobrinus ATCC® 33402TM and 6 mother-child pairs of 16 (37.5%) had genotypic concordance. In addition there was no statistical difference of sociodemographical behaviors and dental behaviors associated with the genotypic concordance of Streptococcus sobrinus ATCC® 33402TM (p>0.05). 
 

Conclusion: AP-PCR is a useful molecular method for strain identification of Streptocccus sobrinus ATCC® 33402TM in dental plaque.