Operative and microbiological validation of visual, radiographic and electronic diagnosis of occlusal caries in non-cavitated teeth judged to be in need of operative care.

The diagnosis of occlusal caries depends upon the correct identification of demineralised enamel and dentine. However, tissue demineralisation precedes bacterial infection so that dentine may be demineralised but uninfected. The presence of a bacterial infection of dentine may be a more relevant factor to be considered when planning to restore a carious lesion. The aim of this clinical study was to validate three techniques for the diagnosis of occlusal caries as demineralised tissue and as infected demineralised tissue during cavity preparation. The study sample was 82 non-cavitated occlusal lesions, judged by various dentists to be in need of operative care. The diagnostic techniques used by the single operator were vision, bitewing radiography and electronic caries diagnosis. The validating techniques were a caries detector dye to stain demineralised tissue, microbiological sampling to determine the level of infection of the dentine and clinical assessment of the dentine at operation. The caries detector dye showed demineralised dentine in 96% of the referred lesions. This demineralisation was reliably predicted by the electronic readings. However, the dentine samples from many teeth yielded only small numbers of bacteria indicating no, or only a very low level of bacterial infection. Neither vision nor electronic readings reliably predict heavily infected dentine. Radiographic evidence of dentine demineralisation was significantly associated with heavily infected dentine and this dentine was soft and wet at operation.