This paper examines the impact on the development of caries, especially on the proximal and the free smooth surfaces, that follows the reduction in sucrose consumption and the increase in consumption of the monosaccharides in the United States and Great Britain. Laboratory evidence shows that sucrose has a special role in proximal- and smooth-surface caries because of its ability to produce extracellular polysaccharides with the mutans streptococci, thus increasing plaque's ability to adhere to the enamel surface. Evidence from human studies, however, is less clear about the relative cariogenicity of the various sugars, possibly because experimental conditions are difficult to maintain in such studies. In the USA sucrose consumption has been diminishing for some year and is now only 47% of the total sugar consumption of 61 kg per person annually. The change in Britain has been less pronounced, sucrose there in 1984 constituted 83% of total consumption of 47.9 kg per person. Sucrose consumption in Britain is, therefore, higher than in the United States, even though the average total consumption of all sugars is higher in the USA. Limited data suggest that proximal- and smooth-surface lesions also constitute a higher proportion of caries incidence in Britain than in USA, and a cause-and-effect hypothesis between these factors is explored. Dietary education for oral health should harmonize with that for general health by emphasizing sensible food choices, which generally means selection of low-fat, low-sugar foods.