The purpose of this study was to evaluate various methods of decontamination of ultrasonic scalers, high-speed handpieces and air-water syringes in dental equipments.

Eimination of possible sources of microbial infection in dental operatories should be of primary importance.

Microbial contamination levels of high speed handpieces, air-water syringes and ultrasonic scalers of 11 dental units in Seoul National University Hospital were evaluated after flushing the lines, alcohol sponge rubbing, or soaking in 0.1% chlorhexidine for 1,3 and 5 minutes.

The result suggests that flushing the lines or soaking the tips in 0.1% chlorhexidine before use of the water systems may reduce the microbial levels. Soaking in 0.1% chlorhexidine for 5 minutes was most effective in reducing bacterial contamination.