Depth of penetration of in vitro root surface lesions.

An acidified gel system was used to produce artificial caries lesions in root surfaces and in enamel. The teeth were exposed to the gel system for two weeks and four weeks, after which the lesions were examined by polarized light microscopy and photographed by standardized techniques. The depths of penetration of the lesions were measured from these standardized photomicrographs. The lesions in root surfaces were deeper than those in enamel for all teeth. After two but not four weeks of exposure in the gel system, the lesions in the root surfaces of anterior teeth were deeper than those in pre-molars.