NORMAL MICROBIOTA ON THE TEETH OF PRESCHOOL-CHILDREN

Plaque samples from nine healthy, preschool children were gathered from the labial and lingual surfaces of primary maxillary and mandibular incisors and the occlusal fissures of primary maxillary first molars over a 16 mth period. Samples were dispersed, serially diluted and cultivated on non-selective and a variety of selective media. Representative colony types were counted, subcultured and microorganisms identified using morphological, physiological, serological and acid end-product analyses. Non-parametric statistical methods, including a permutation analysis, were used to analyse the data. The communities on each surface were much more complex than has been reported previously. Streptococcus was the dominant genus at each surface except for the lower incisor where Actinomyces dominated. Neisseriae was more dominant than veillonellae at all dental surfaces. Gram-negative rods and filaments including Haemophilus, Fusobacterium, Capnocytophaga, Leptotrichia and Porphyromonas species were also present on all surfaces at varying levels and persistence. This investigation has shown that many potential oral pathogens, both dental and periodontal, are components of the commensal oral microbiota of preschool children and exist in the absence of overt disease.