Mutans streptococci strains prevalence before and after cavity preparation during Atraumatic Restorative Treatment.

Critics argue that all carious dentine is not removed from the hand-prepared cavity during the Atraumatic Restorative Treatment (ART) procedure, and that the caries process is soon resumed. The aim of this study was to determine the effectiveness of ART in removing carious tissue, by investigating the numbers of mutans streptococci and lactobacilli, with emphasis on the prevalence of Streptococcus mutans and Streptococcus sobrinus strains before, and after ART treatment of dental caries. Two microbiology samples were collected. The first sample was removed from the centre of the carious lesion at the enamel-dentine junction, and the second was collected from the centre of the hard cavity wall above the pulp, after the soft infected dentine had been manually removed. A total of 71 mutans streptococci isolates from 31 children and 40 carious teeth were subcultured, biochemically characterised and genotyped by the arbitrarily primed polymerase chain reaction (AP-PCR). Results showed a significant decrease in TVC (P<0.0001), mutans streptococci (P < 0.0001) and lactobacilli (P = 0.0002) after cavity preparation. AP-PCR identified S. mutans strains that were undetectable during biotyping, and divided clinical isolates into two main clusters. In all, 63% (45/71) of isolates from the carious lesions comprised S. mutans strains. After cavity preparation, this was reduced to 35% (25/71), of which 30% (21/71) were S. mutans and the remaining 6% (4/71) S. sobrinus strains. The number of mutans streptococci strains was below detectable levels in 19 of the prepared cavities. The significant decrease in bacteria after manual cavity preparation demonstrates the reliability of a standardized ART technique, yet the presence of S. mutans strains shows that the effectiveness of the ART procedure can vary during treatment and between dental practitioners.

Mutans streptococci and other caries-associated acidogenic bacteria in five-year-old children in South Africa.

Correlations between mutans streptococci and caries are inconsistent; some studies show that early caries may occur with other bacterial species possessing the ability to survive, interact and compete with mutans streptococci. This study looked at the relationship between mutans streptococci, Lactobacillus, Actinomyces and Veillonella in saliva and plaque collected from four tooth sites in two ethnic groups, with and without caries. All samples were collected and cultured onto selective media. Colonies were enumerated and identified using biochemical tests. Pearson correlations showed low yet statistically significant correlations between plaque mutans streptococci counts and the number of decayed surfaces (ds) and decayed, missing and filled surfaces (dmfs) of primary teeth in blacks and in coloreds (historical race classification). Salivary mutans streptococci counts correlated with ds and dmfs in coloreds. No relationship was found between ds, dmfs and Lactobacillus, Actinomyces or Veillonella numbers. Significant associations were evident between plaque mutans streptococci and Veillonella and Lactobacillus in black children with caries and between plaque mutans streptococci and Actinomyces and Lactobacillus and Veillonella in colored children. Hence, oral microbes are in constant flux but have interrelationships in children with caries.