title: Distribution ofStreptococcus mutansandStreptococcus sobrinusin Dental Plaque of Indian Pre-School Children Using PCR and SB-20M Agar Medium.
abstract: BACKGROUND
  Dental caries is one of the most common infectious diseases affecting the oral cavity. Among the oral bacteria, mutans streptococci have been implicated as major cariogenic bacteria as they can produce high levels of dental caries causing substances such as lactic acid and extracellular polysaccharides.
  
  
  OBJECTIVE
  The aim of the study was to detect the presence ofStreptococcus mutansandStreptococcus sobrinusin dental plaque by using Polymerase Chain Reaction (PCR) method, quantification of these micro-organisms using Modified Sucrose-Bacitracin (SB-20M) agar medium and to correlate their presence in Caries Active (CA) and Caries Free (CF) pre-school children.
  
  
  METHODS
  Sixty-eight pre-school children, in the age group of 3-5 years were divided equally into 34 CA and 34 CF children. Dental plaque samples were obtained for detection of these microorganisms by PCR method and quantification was done using SB-20M culture medium. The data was analyzed using statistical software SPSS version 16. For statistical analysis, the frequencies and means of Colony Forming Units (CFU) were used with CI = 95%. For bivariate analysis, Fisher exact test was used at 5% level of significance. The comparison of mean of number of CFU ofS. mutansandS. sobrinuswas made by Mann Whitney U test and Spearman's Rho test at 1% level of significance was used for correlation between dmft and CFU in CA group.
  
  
  RESULTS
  The results showed thatS. sobrinuswas significantly higher in CA group as compared to CF group whereasS. mutansshowed no significant difference. On quantification of these micro-organisms,S. sobrinuswas present in significantly higher numbers in CA group as compared to CF group. On correlating the CFU/ml of the micro-organisms with the dmft index, both the micro-organisms showed a positive correlation.
  
  
  CONCLUSIONS
  We conclude thatS. mutansandS. sobrinuswere detected in higher numbers in CA children as compared to CF children. PCR is a sensitive, specific, rapid and an effective method for the detection of oral microorganisms.
authors.affiliation: Senior Resident, Department of Dental Surgery, Dr. Ram Manohar Lohia Hospital , New Delhi, India .
authors.forename: Divya
authors.initials: D
authors.lastname: Singla
authors.affiliation: Professor and Head, Department of Pedodontics and Preventive Dentistry, People's College of Dental Sciences and Research Centre , Bhopal, Madhya Pradesh, India .
authors.forename: Arun
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Professor and Head, Department of Pedodontics and Preventive Dentistry, ITS - Centre for Dental Studies and Research , Muradnagar, Ghaziabad, Uttar Pradesh, India .
authors.forename: Vinod
authors.initials: V
authors.lastname: Sachdev
authors.affiliation: Reader, Department of Pedodontics and Preventive Dentistry, ITS - Centre for Dental Studies and Research , Muradnagar, Ghaziabad, Uttar Pradesh, India .
authors.forename: Radhika
authors.initials: R
authors.lastname: Chopra
keywords: Age group; Analysis; Dental caries; Genetics; Oral microflora