Preliminary impedance spectroscopy study for carious lesions detection

This preliminary study proposes the use of impedance spectroscopy as additional diagnostic method in clinical practice to assess carious lesions. The carious process leads to a characteristic loss of mineral and a subsequent increased porosity, which results in a higher liquid content than sound tissue. The absorbed liquid contains different ions coming from the oral environment which, together with the increased porosity, contribute to change the impedance of the tissue. Impedance measurement is able to detect such tissue modifications and, therefore, it can be a suitable approach for assessing the presence and the status of carious processes on teeth. Moreover, compared to other diagnostic techniques it is more promising, also for the development of in-vivo measurements, owing to its safety, reliability, simplicity, rapid response, cost-effective, robust, and adequate detection limit. This study compares impedance spectroscopy measurements collected by using two different types of probes for monitoring teeth with and without carious lesions. The authors used a Ni-Cr wire electrode with a diameter of 0.5 mm, and a hydrogel agar probe with a diameter of 5 mm. Impedance measurements were carried out in-vitro by means of the Ivium-n-Stat potentiostat with a two-electrode setup, on the occlusal surfaces of teeth with and without carious lesions; then, the impedance spectra were recorded and analyzed. The preliminary results highlight that both experimental probes allow detecting a shift in impedance phase spectra, which happens at different frequencies and can be correlated to healthy teeth and the carious lesions, respectively.