Prevention of microbial contamination of the dental unit caused by suction into the turbine drive air lines.
OBJECTIVE
To determine whether a specially designed antisuction device can prevent the bacterial contamination of the drive air lines of the dental turbine that is caused by suction when the turbine is stopped.


METHODS
A dental unit with and without the antisuction device and three different types of sterilized handpieces were used in the tests. Each turbine was operated in air, then submerged into a bacterial suspension of E. coli and enterococci for 3 seconds, removed, and stopped. This procedure was repeated 10 times. Possible bacterial contamination of the drive air lines was examined by submersing the head of a sterilized handpiece with the turbine running into a nutrient broth for 30 seconds. The broth was incubated at 35 degrees C up to 2 days.


RESULTS
After use of the conventional dental unit, bacterial growth of drive air lines was found in 10 of 150 broth samples. After the installation of the antisuction device no bacterial growth was found in any of the 138 samples. The difference in the contamination frequencies is statistically significant (p = 0.011, Fisher's two-sided exact test).


CONCLUSIONS
The drive air lines of the turbine in the dental unit may become contaminated despite the sterilization of handpieces. The antisuction device installed into the dental unit was found to prevent the contamination. With the exception of possibly immunocompromised patients, the transmission of microbes by exhaust air may be too small to cause infections. However, transmission of oral material between patients should be prevented in dental practice.
Ojajärvi
J
J
Department of Public Health, University of Helsinki, Finland.
D000388:Air; D001419:Bacteria; D003428:Cross Infection / Q000517:prevention & control; D003470:Culture Media; D003754:Dental High-Speed Equipment; D003762:Dental Instruments; D016983:Enterococcus / Q000254:growth & development; D004866:Equipment Contamination / Q000517:prevention & control*; D004926:Escherichia coli / Q000254:growth & development; D006801:Humans; D013242:Sterilization; D013396:Suction / Q000295:instrumentation*
D003470:Culture Media