An in vitro assessment of the extent of caries under small occlusal cavities.

Many clinicians take for granted that occlusal caries which is just visible as a cavity is extended (deep) into the dentine. This study was aimed at quantifying this opinion. The study was carried out with 60 molars containing small but visible occlusal cavities. After taking bite-wing radiographs the crowns were separated from the roots and embedded. 700-microns sections were cut and glued on plastic sheets. X-ray pictures were taken of the sections which were scored by independent examiners. The bite-wings provided inaccurate estimates of the extent of caries. Radiographs of the sections revealed that about 25% of the molars had caries which reached just to the dentino-enamel junction, while the remaining 75% showed caries extending far into the dentine.