Anti-suck-back Effects of Dental Air Turbine Handpieces by Themselves

Abstract

The suck-back phenomenon of dental air turbine handpieces causes the intake of saliva, blood and cut shavings from the oral cavity, contaminating not only the air turbine handpiece, but also the tube connector and the unit. Cross infection can occur even if the air turbine handpiece is changed for each patient. This study evaluated the anti-suck-back effect of four new air turbine handpieces models produced by different companies. 1. Measuring suck-back pressure: The suck-back pressure from the front face of the air turbine handpiece, back face and whole head of the air turbine handpiece were measured. The air turbine handpiece was allowed to rotate within a sealed flask. Then rotation was stopped and the amount of colored water drawn from the beaker into a glass tube was examined by maximum water height. 2. Verification of suck-back: The air turbine was started and then stopped in a floating flask under fluorescent mist caused by another air turbine handpiece (mist condition), fluorescent nebulization with an ultrasonic nebulizer (fume condition) and full immersion of the head of the air turbine handpiece in fluorescent stain solution. The cycle of starting for 2 seconds and stopping for 5 seconds was repeated 1, 2, 3, 5, 10, 30, 50, 100, 200, 300, 400 and 500 times until fluorescent stains on a gauze pad covered at the exhaust vent became visible in fluorescence microscopy images under each condition. The exhaust vent parts on the coupling as well as on the air turbine handpiece head were observed by fluorescence microscopy for the existence of fluorescent stains. As a result, the water height for each part of one air turbine handpiece was below 0 mm. Except for under full immersion, this model did not have any visible penetration of fluorescence to the exhaust vent even after 500 cycles under mist/fume conditions. Conversely, the other air turbine handpieces showed suck-back phenomena. In full immersion of the whole head of the air turbine handpiece, all handpieces showed suck-back phenomena immediately. As the handpiece heads are not completely sealed, full immersion must be avoided to prevent liquid intake. In conclusion, one air turbine handpiece showed the possibility avoiding suck-back.