The Microflora Associated with Developing Lesions of Nursing Caries

Abstract

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.

The Effect of Lowering the pH on the Composition and Metabolism of a Community of Nine Oral Bacteria Grown in a Chemostat

“…rnutans, suggest that the role of these bacteria in human plaque may have to be re-assessed. Certainly, the results presented here support the proposal that high levels of Veillonella might reflect environments with a high lactate concentration (Boyar & Bowden, 1985;Milnes & Bowden, 1985) since this was the predominant fermentation product during growth in the chemostat at pH 4.1 (Table 4). This change in pattern could not be attributed to an increase in the numbers of bacteria with a homolactic fermentation pattern.…”

“…Veillonella cannot metabolize sugars but can form food-chains with lactate-producing bacteria (Mikx & van der Hoeven, 1975) and, after studies with gnotobiotic animals (Mikx et al, 1972), it was proposed that these organisms might modify the carious process by converting lactic acid to weaker acids (acetic and propionic). However, the recent findings of increased levels of Veillonella at carious sites in man (Boyar & Bowden, 1985;Milnes & Bowden, 1985), coupled with the in vitro observations that members of this genus can stimulate the growth (McKee et al, 1983) and glycolytic activity (Hamilton & Ng, 1983) of 5'. rnutans, suggest that the role of these bacteria in human plaque may have to be re-assessed.…”

Molecular Analysis of Bacterial Species Associated with Childhood Caries

“…Veillonella metabolizes lactic acid produced by other species to form propionic and acetic acids, both weaker acids than lactic acid and so less capable of dissolving tooth enamel. Species of Veillonella have been detected in high proportions in progressing incipient lesions (20), and in vitro studies have shown that the combination of Veillonella and S. mutans allows more acid production and greater demineralization than does S. mutans alone (23). Veillonella has also been shown to stimulate glycolysis in S. salivarius by acting as a sink for the lactic acid produced (10).…”

Genetic Profiling of the Oral Microbiota Associated with Severe Early-Childhood Caries

“…other bacterial species may also be associated with caries initiation and development. Clearly, the concept that dental caries is a polymicrobial infectious disease was well supported by the published literature (7,8,28,33). Further studies, however, are needed to determine whether caries-associated plaques are more or less diverse overall and to elucidate the determinant associated with the microbial composition.…”