Effectiveness and safety of a sonic vibratory endodontic instrument

An air‐driven sonic vibratory handpiece to which specially designed K‐type files are attached has been developed. When activated, the root canal instruments will vibrate in a whirling motion, and when moved up and down, will abrade the root canal wall. The sonic system was tested in simulated root canals in plastic blocks and in usage tests in dogs' teeth. Forty‐nine roots in 3 dogs were divided into 3 groups. Two of the groups were instrumented with the sonic device under continuous irrigation with 2.5% NaOCl or 15% EDTA. The 3rd group was treated with conventional chemomechanical instrumentation and 2.5% NaOGl. The teeth were then extracted, fixed and split in a longitudinal direction and the root canals examined in the scanning electron microscope. After hand instrumentation and sonic instrumentation using NaOCl for irrigation, the canal wall was covered by a smear layer and dentin chips and occasional tissue remnants were seen. An extraoral fine mist of NaOCl was seen during continuous irrigation with this medicament, causing eye soreness in the operator. Continuous irrigation with EDTA during sonic instrumentation removed the smear layer and gave clean canal walls. The vibratory files appeared safe and size 20 followed curved canals well. The effectiveness of the sonic device was similar to hand instrumentation. It considerably improved the ease and, to some extent, the speed of root canal instrumentation.