The Microflora Associated with Developing Lesions of Nursing Caries

Longitudinal microbiological examinations of dental plaque from children who developed nursing caries were carried out for 1 year. 9 children were included in the study, 5 of them developed caries lesions, while 4 remained caries-free. Two susceptible sites, the labial and palatal surfaces of the primary first incisor and a control site, the labial of the primary first mandibular incisor, were sampled. The plaque samples were analysed for the presence and numbers of members of Streptococcus, Actinomyces, Lactobacillus and Veillonella. The results showed significant differences between the levels of Streptococcus mutans, Lactobacillus and Veillonella at the sites which developed caries and the control sites in the same mouths. However, the susceptible sites which did not develop lesions in caries-active children supported a flora which was not significantly different from that of the lesion sites. This suggests that other factors beyond those which allow the establishment of a ‘pathogenic’ flora are involved in the development of a lesion. Veillonella were found in significantly higher amounts on the susceptible surfaces when compared to the controls. This finding was independent of the development of a lesion. It may be that the higher levels of Veillonella at susceptible sites reflect an increase in lactic acid in plaque. As some of these sites developed lesions, it does not seem likely that Veillonella were modifying the caries attack. There were no significant differences between the susceptible sites and control sites in the 4 children who did not develop caries. However, in 1 of these children, persistently high levels of S. mutans were present at susceptible sites.