Aerosol generation by two ultrasonic scalers and one sonic scaler. A comparative study

The purposes of this study were to compare the amount of aerosols generated from ultrasonic and sonic scalers and to measure the potential depth of respiratory tract penetration. Forty subjects were randomly assigned to receive instrumentation with the magnetostrictive, piezoelectric, or air turbine scaler. The Anderson Air Sampler collected total baseline airborne microbes for 20 minutes prior to treatment and for 20 minutes during instrumentation. This cascade impactor system measures the degree of microbial penetration in a simulated respiratory system. Blood agar plates from the sampler were incubated for 24 hours at 37 degrees C. Colony forming units per cubic foot of air (CFUs/cu. ft.) were enumerated by one blind examiner using a Lab Line Colony Counter. Data for total microbial CFUs/cu.ft. and CFUs/cu.ft. by sampler level were analyzed on the log-transformed data using ANCOVA. Baseline values of airborne bacteria served as the covariate. Results showed no significant difference in mean combined total CFUs/cu.ft. for the magnetostrictive, piezoelectric, or air turbine sonic scalers. The magnetostrictive scaler generated the lowest CFUs/cu.ft. at the deepest level of penetration; however, no significant difference in level of penetration was found among the three scalers.