SURFACE-SPECIFIC ELECTRICAL OCCLUSAL CARIES DIAGNOSIS - REPRODUCIBILITY, CORRELATION WITH HISTOLOGICAL LESION DEPTH, AND TOOTH TYPE DEPENDENCE

Electrical conductance measurements are being used experimentally for occlusal caries detection. Recently, it was suggested to cover the fis sure system with a conducting medium, resulting in a surface-specific measurement. It was the aim of this study to determine in vitro the re producibility of this modified technique for occlusal caries in poster ior teeth, to determine for a large study sample the correlation betwe en the electrical measurements and histological lesion depth, and to e valuate the difference between results for premolars and molars, For t he reproducibility determination, surface-specific electrical resistan ce measurements were made using a sample of 68 posterior teeth. Eight operators performed measurements on all teeth, and repeated measuremen ts on 24 teeth. The validity study included the previous sample and th e collected samples from two more studies, resulting in a total sample of 325 posterior teeth. One operator had performed electrical resista nce measurements on all teeth in the sample. Reproducibility was good: mean Pearson's correlation coefficient 0.89 (+/-0.05) for interexamin er correlation, and 0.86 (+/-0.12) for intra-examiner correlation, usi ng log (resistance) as the result parameter. The correlation coefficie nt between log(resistance) and histological lesion depth for the large sample was -0.78 for all teeth, -0.64 for premolars, and -0.73 for mo lars. The regression line for molars was located below the regression line for premolars: at a hypothetical histology score of 2.5 (a dentin e caries threshold) the estimated resistance threshold would be 507 k Ohm for premolars, and 233 k Ohm for molars. Converted to Electronic C aries Monitor (ECM) readings, the difference is about 1.4 on the ECM s cale. It was concluded that the in vitro reproducibility of the descri bed surface-specific method for electrical resistance measurement is v ery good, even for inexperienced operators. The correlation between me asurements and histological lesion depth is moderate to good, The meth od is sensitive to electrode area differences, which will result in di fferent clinical cut-offs for caries diagnosis in premolar and molar t eeth.