Effect of ultrasonic instrumentation on the retention of simulated cast crowns.

The effect of ultrasonic instrumentation on the retention of cemented cast restorations was studied. Forces required to dislodge castings from specimen assemblies subjected to ultrasonic vibrations did not differ significantly from those required to cause failure of noninstrumented specimens. The results indicate that clinical application of the ultrasonic device would not affect adversely the retention of properly cemented and well fitting cast restorations.