The establishment of the bacterium Streptococcus mutans in dental plaque and the induction of caries in macaque monkeys (Macaca fascicularis) fed a diet containing cooked-wheat flour.

A diet containing 50.7 per cent cooked wheat flour (78 per cent starches and dextrin) was fed to 82 monkeys from weaning for up to 407 days. Streptococcus mutans became established naturally and remained at a high level (25-40 per cent of the total anaerobic colony count) in the dental plaque of the majority of animals but in only 2 were carious lesions detected. The predominant Strep. mutans serotypes isolated from plaque were c, e and h, which produced acid when incubated with the diet in vitro. Twenty-five monkeys were switched to a cariogenic high sucrose diet, and 6 months later 72 per cent of them had carious lesions (mean +/- SD = 6.5 +/- 6.6 carious lesions per monkey). The failure of the starch diet to promote tooth decay in monkeys supports the general conclusion that starch and starch products are virtually non-cariogenic for man.