The accuracy of electrical method for microleakage evaluation by a three-dimensional analysis

Objectives This in vitro study aimed to investigate the accuracy of an electrical method for the evaluation of microleakage by a three-dimensional analysis of dye penetration. Methods Coronal cavities were prepared on buccal, palatal or lingual surfaces in extracted human molars. The cavities were then filled with resin composites and were subjected to 10,000 load cycles (425 g). Before cavity preparation and after load cycling, physiological saline was applied and wiped off, and the change in conductance was measured across the margin of the restoration in each specimen. After dye penetration, the specimens were reduced by 100 μm in a direction parallel to the cavity floor, from the surface of the restoration to the cavity floor. The sequence of reducing the sections by 100 μm and image taking was repeated. Three-dimensional images of dye penetration were made and the proportions of the interface showing penetration were calculated. Results Pearsonʹs correlation coefficients between changes in conductance and the surface area of dye penetration, between these and the rate of dye penetration, and between these and the depth of dye penetration were 0.932, 0.920 and 0.732, respectively. The correlations were significant (p < 0.05). Conclusions The results of this electrical method for microleakage evaluation showed stronger correlations with the three-dimensional amount of marginal leakage (surface area of dye penetration and rate of dye penetration) than the two-dimensional amount (depth of dye penetration).