High-frequency noise in dentistry.

Earlier studies have revealed that dentists have higher hearing thresholds than expected. The aim of this study was to evaluate the noise levels of current dentistry equipment under very controlled conditions. This noise study was carried out in the Acoustics Laboratory of Kuopio Regional Institute of Occupational Health, the background noise of which is about 0 dB(A). Working noise was simulated by drilling a polyacetal plate. During drilling and idling, the noise of the hand pieces was measured over a reflecting plane on the hemisphere surface, the radius of which was 0.3 m, and 10 noise samples were picked for each hand piece. The average sound pressure level and the sound power level of the devices were calculated applying the standard ISO 3744. The measurement and analysis were done in the one-third octave bands of 25-80,000 Hz. The measuring instruments used were the B&K 4135 microphones, the B&K 2633 preamplifiers, the B&K 2811 multiplexer, and the B&K 2133 real-time analyzer with the ZT 0318 high-frequency expansion unit. During the simulated work, the average A-weighted sound pressure level of the new and old hand pieces was 76-82 dB(A), that of the power suction tube 77 dB(A), the saliva suction tube 75 dB(A), and the ultrasonic scaler 83 dB(A). The average ultrasound level of the ultrasonic scaler was 107 dB at the one-third octave band of 25,000 Hz.