Dental electromagnetic tomography: properties of tooth tissues

An electromagnetic tomography (EMT) system, based on mutual inductance measurements is described for imaging tooth structures. The system consists of an array of miniature coils. The inductor coils are excited to generate tooth images by measuring the conductivity and permeability across a sensing pair. The apparatus is similar to conventional capacitance and electrical impedance systems for existing medical applications. Conductivity analysis for different tooth tissues and dental restorative materials have been investigated. The results illustrate that there are significant differences in conductivity between enamel, dentine, demineralised dentine, glassionomer, composite and amalgam. The difference between a healthy dentine and a demineralised sample produces results with approximately a 20:1 ratio. The conductivity of glassionomer, composite and amalgam have also been measured and found to have ratios of 15:30:1 respectively