CONTAMINATION OF THE TURBINE AIR CHAMBER - A RISK OF CROSS-INFECTION

In the present work, we evaluated (a) the influx of contaminating flui d into the air chamber when a high-speed turbine stops rotating, (b) t he significance of a series of variables (type of handpiece and dental unit, shape of the bur, number of stops set on the turbine) which con dition it, and (c) the time required to expell the contaminating fluid from the turbine head. Results showed that contamination takes place every time the turbine stops rotating with the bur in contact with an external fluid. The main variable affecting the influx of contaminatin g fluid into the air chamber of the turbine head was represented by th e shape of the bur (F=54.9; p<0.01). Another significant variable was the type of handpiece and dental unit (F=7.3; p<0.01). The number of s tops set on the turbine was irrelevant (F=0.03; p=n.s.). The expulsion of the contaminant from the turbine head showed 2 different exponenti al rates: a very rapid-elimination phase within 30 s and a slow-elimin ation phase between 60 and 300 s. In order to remove over 99% of the c ontaminant from the air chamber, a turbine had to run for more than 4- 7 min depending on the type of the handpiece. In conclusion, data from the present study suggest that a significant cross-infection potentia l exists with high-speed handpieces whenever they are only externally scrubbed and disinfected so the internal cleaning and sterilization be tween patients is mandatory. The practice of flushing by running the t urbines between patients should be discouraged.