Distribution of selected cariogenic bacteria in five different intra-oral habitats in young children.

Knowledge of the colonization patterns and composition of the oral microbiota can lead to a better understanding of disease initiation. The aim of this study was to examine the distribution of selected cariogenic bacteria in samples from five different oral habitats in young Greek children. Ninety-three children 3-12 years old (mean + SD 7.9 +/- 2.5) (60.2% male, 39.8% female) participated and split into three different age groups: primary (3-6 years), early mixed (6-9 years), and mixed dentition (9-12 years). Samples for bacterial enumeration were taken from saliva, supragingival and subgingival plaque, tongue dorsum, and soft tissues from each child, and were further analysed using checkerboard DNA-DNA hybridization. Mean counts and proportions of all the test bacteria differed significantly among sample locations. Cariogenic bacteria were present in almost all healthy children. Mean proportions of Streptococcus mutans isolated from soft tissue and Streptococcus sanguinis from soft tissue, subgingival and saliva samples increased significantly with age, whereas the opposite was seen for Lactobacillus acidophilus. Cariogenic bacteria were present in almost all young children. Soft tissues, saliva, and tongue were more often colonized by cariogenic streptococcal species than teeth. These surfaces may serve as reservoirs for oral pathogens, requiring attention during preventive interventions.