The specificity of caries detector dyes in cavity preparation

The specificity of two caries detector dyes (0.5% basic fuchsin and 1.0% acid red) was investigated in vitro using extracted human permanent and deciduous teeth. Although the dyes stained carious dentine, sound circumpulpal dentine and the enamel-dentine junction could also be stained. Backscattered electron imaging showed that the level of mineralisation in these two parts of the tooth was lower than in normal dentine. Susceptibility to dye staining therefore appears to be a feature of reduced mineral content rather than being specific for a carious lesion. Whilst use of basic fuchsin should be avoided in view of its carcinogenic potential and ability to stain sound coronal dentine, acid red should also be used with caution and its use on the pulpal surface of deep cavity preparations would appear to be contraindicated. Use of these dyes may result in the unnecessary removal of sound dentine.