Electronic diagnosis of occlusal caries in vitro: adaptation of the technique for epidemiological purposes.

Most studies on electronic diagnosis of occlusal caries have involved taking site-specific conductance measurements. Airflow around the electronic caries monitor probe removes superficial moisture and the conductance measurement reflects the caries status of that part of the fissure beneath the probe tip. This is an appropriate technique for a clinician to use to monitor caries status, and it could be adapted for use in epidemiological studies and clinical trials. The present work investigated an alternative technique using a jelly as a contact medium over the entire fissure system so that the probe might record the overall caries status of the tooth reflecting the worst affected site. Readings were taken on 96 extracted teeth with dye-coloured jelly acting as a contact medium. Readings were repeated on 32 teeth. Histological validation of caries status was carried out by visual examination of serial sections through each tooth to note the deepest lesion. The sensitivity and specificity of the overall electronic caries monitor readings were calculated for all lesions and dentine lesions only using selected resistance cut-off points and presented as a series of Receiver Operating Characteristic (ROC) curves. The optimum sensitivity and specificity values were, for all lesions: 61% and 86%, and for dentine lesions: 76% and 76% respectively. The reproducibility of the readings was acceptable (Kappa values for all lesions = 0.76, for dentine lesions = 0.55). The technique warrants further study as an overall reading may be more appropriate for epidemiological and clinical trial use.