Evaluation of adhesive defects using an ultrasonic pulse-reflection technique.

The purpose of this study was to examine the application of an ultrasonic pulse-reflection technique for the evaluation of adhesive defects. First, the sonic velocities in the enamel and dentin of human molars and bovine incisors were measured with a pulsar receiver attached to an ultrasonic transducer. The identification of the dentino-enamel junction and pulp-dentin interface using the ultrasonic method based on intrinsic sonic velocities showed good agreement with the actual measured thicknesses. Next, a cemented restoration with artificial faults was prepared. Half of the Au-Ag-Pd alloy plate area was cemented to the dentin slab using luting resin cement. The adhesive interface was evaluated with a high-resolution ultrasonic imaging system. Clear internal faults were evident from the ultrasonic tomogram. The findings of this study suggest that the ultrasonic pulse-reflection technique may be useful for inspecting and imaging structural defects of adhesive interfaces.