Abstract: There is described an electrode assembly for passing electrical current through at least part of a tooth, the assembly comprising: an electrode holder; and a plurality of resilient projecting elements coupled to the holder, each element comprising one or more electrodes, the assembly being arranged in use such that when the assembly is positioned adjacent a tooth, the electrodes contact respective parts of at least one surface of the tooth. The assembly is preferably for use in A.C. impedance spectroscopy for caries detection and monitoring.

Abstract: There is described a method o monitoring the structure of a tooth comprising:—placing an electrode carrier, having at least three electrodes, adjacent the tooth such that the electrodes contact at least one of the occlusal, approximal or free smooth surfaces of the tooth; selecting pairs of the carrier electrodes, one electrode of each selected pair to act as a contact electrode, and the other as a counter electrode; for each selected pair of electrodes, passing an alternating electrical current between the electrodes so as to form a circuit from the electrodes and a respective part of the tooth at least between the electrodes, and monitoring the electrical response for the circuit; and processing the monitored response for each pair of electrodes so as to determine structural information relating to the respective parts of the tooth. Apparatus for carrying out the method is described. The method is preferably an impedance spectroscopy technique, for caries detection and monitoring.