Hidden Dentinal Caries Detection Using a Novel Electrical Impedance Device

Objective: t he aim of this in vitro study was to assess the ability of a new electrical ac-impedance device (CarieScan®) to detect “hidden dentinal” occlusal caries. Methods: 128 occlusal sites on 72 extracted human molar and premolar teeth were scored for caries by a single examiner experienced in the ICDAS caries coding system – a 6-point visual assessment of clean dry teeth. The teeth were subjected to X-ray micro-Computed Tomography (XCT) and the resulting image slices scored independently for caries on a 7-point visual + XCT reference scale by 3 different examiners, using a consensus method to resolve any disagreements. The teeth were also examined using the novel electrical device by one experienced examiner.  For this analysis, “hidden dentinal” occlusal caries was defined as sites scored as visually non-cavitated lesions (using ICDAS criteria) but showing dentine lesions on the reference scale (XCT). Results: 42 sites were found by XCT to have a score of 6 (caries extending into outer half dentine) and 7 to have a score of 7 (caries into inner half dentine) where the ICDAS code was either 1 or 2 (i.e. where an enamel lesion is visible, but the surface is intact). Of the 49 sites with any dentinal caries, the novel device detected 15 as being into dentine (= 31%) and a further 23 as being in the inner 1/3 of enamel (= 47% of “hidden dentinal” lesions). Of the 7 sites with score 7 by XCT, the novel device detected 7 (100%) as being deep in dentine; of the 42 sites scoring 6 by XCT, the novel device detected 5 (12%) as being in dentine. Conclusion: a novel electrical impedance device was able to detect 31% of all the hidden dentine lesions not detected by optimal clinical visual assessment and 100% of deep hidden dentine lesions.