In vitro and in vivo measurement of remaining dentin thickness.

Experiments were performed in vitro on extracted human teeth and in vivo on dog teeth to determine the accuracy of a pulse-echo mode with an ultrasonic micrometer in measuring remaining dentin thickness. The accuracy of the ultrasonic micrometer measured remaining dentin thickness was compared with direct caliper measurements in measuring human dentin discs (correlation coefficient, r = 0.99). After modification of the delay line tip (focusing tip), the device was found to be highly accurate on both prepared extracted human teeth (r = 0.87) and in vivo on dog teeth (r = 0.92). The use of ultrasonic technology to measure remaining dentin thickness looks promising. Further research needs to be performed to make the device more clinically useful.