title: Differences of the oral colonization by Streptococcus of the mutans group in children and adolescents with Down syndrome, mental retardation and normal controls.
abstract: OBJECTIVE
  to compare the concentration and serotype of Streptococcus mutans in saliva of Down syndrome (DS), mental retarded (MR) and healthy control (C) individuals of the Región Metropolitana Sur of Santiago of Chile.
  
  
  METHODS
  Hundred and seventy nine male and females children and adolescents, aged between 5 to 19 years, 59 DS, 60 MR and 60 C were studied. Saliva samples were cultured in TYCSB agar for quantification, biochemical and serological tests. ANOVA and Chi-square for homogeneity tests were applied.
  
  
  RESULTS
  C, DS and MR presented Streptococcus mutans (serotypes c, e, f) and Streptococcus sobrinus (d, g, h), but only among DS and MR non-typifiable (No-tip) Streptococcus mutans were found. MR and DS showed higher bacteria concentration scores than C (P=0.001). Serotypes showed a significant heterogeneity of concentration scores: d, g, h showed the highest and No-tip the lowest one (P = 0.037).
  
  
  CONCLUSIONS
  No-tip bacteria were absent in C and present in MR and DS; this result indicates different immune and ecological conditions among these human groups. The score of Streptococcus mutans in saliva was higher in DS and MR than in C.
authors.affiliation: Servicio de Odontología y Cirugía Maxilo Facial, Escuela de Medicina, Pontificia Universidad Católica de Chile. alinossi@gmail.com
authors.forename: Alfredo G
authors.initials: AG
authors.lastname: Linossier
authors.forename: Carlos Y
authors.initials: CY
authors.lastname: Valenzuela
authors.forename: Héctor
authors.initials: H
authors.lastname: Toledo