A REEVALUATION OF ELECTRICAL-RESISTANCE MEASUREMENTS FOR THE DIAGNOSIS OF OCCLUSAL CARIES

Clinical and radiographic diagnosis of occlusal caries is difficult. R esistance measurements in pits and fissures have shown better sensitiv ity compared with the more conventional methods of diagnosis. Two mach ines have been manufactured for this purpose: the Vanguard and the Car ies Meter L. The aims of this study were to calibrate the readouts of these machines against a variable standard resistance box and use the Vanguard to compare readings taken in vivo and in vitro after extracti on of the teeth. The diagnositc accuracy of clinical, radiographic, Va nguard and Caries Meter L diagnoses were also assessed. One hundred oc clusal sites in 40 teeth of 20 patients were investigated in vivo with the Vanguard, noting clinical and radiographic appearances. The teeth were then extracted and the Vanguard readings repeated in vitro, toge ther with Caries Meter L readings. The in vivo/in vitro comparison bet ween Vanguard readings showed excellent reproducibility (Cohen's Kappa = 0.80). The sensitivity and specificity for the different examinatio n techniques at the enamel level of diagnosis were 27% and 89% for vis ual, 6% and 100% for radiographic, 81% and 78% for the Vanguard and 74 % and 74% for the Caries Meter L. In conclusion, this study supports t he renewed interest in resistance measurements as a diagnostic techniq ue and indicates that the in vitro model used gives results comparable to those in vivo.