An electrical method for examining remaining dentine thickness

Cylindrical cavities were prepared on the buccal surfaces of 78 dog teeth. Impedance between cavity floor and oral mucous membrane was measured with a caries meter and correlated with remaining dentine thickness (RDT). Statistically significant, positive correlations (P less than 0.01) were found to exist between RDT and impedance in upper and lower premolars, however, a considerable degree of variation was observed in the RDT at an impedance value of less than 30 k omega. It is concluded that measurement errors make it difficult to determine RDT with electrical methods and that an impedance of 40 k omega is required to prevent bacterial contamination of pulpal tissues.