The polarized light microscopic appearance of caries-like lesions adjacent to restored cavities in the crowns and roots of extracted human teeth.

Longitudinal clinical studies indicate consistently that secondary caries is the major cause of failure of restorations. Recently there has been an increase in the number of fluoride-containing materials coming to the market place and this has renewed the debate about the cariostatic effectiveness of such materials. The present study examined the histologic appearance of caries-like lesions adjacent to a non-fluoride-containing material (amalgam), a low fluoride-containing material (composite) and a moderate fluoride-containing material (glass-ionomer). The artificial caries system used to produce lesions has been previously reported and is a microbial system using Streptococcus mutans NCTC 10832. The lesions produced were similar to naturally occurring lesions in many respects, indicating the usefulness of this in vitro technique. Variations in the appearance of lesions were found adjacent to the different materials and the effect of the fluoride contained within two of the materials is discussed.