Abstract
Initiation of carious lesions was studied in young rats during mastication and non-function induced by unilateral extraction of upper right molars. Diets containing 66% corn caused less initial sulcal lesions than corresponding diets containing 66% sugar. The diets containing fine particles induced more initial lesions than the coarse-particle diets (this difference being less marked in the corn diets). On the corn diets there were more sulcal lesions during mastication than non-function; the reverse is true for the sugar diets.