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Sterilization efficacy of a forced-air, dry heat sterilizer
W F Hohlt1, M A Sheldrake, C H Miller
1Department of Oral/Facial Development, Indiana University School of Dentistry, Indianapolis.
Purpose:
To evaluate forced-air, dry heat sterilizer and test its ability to kill spores of Bacillus subtilis during both available cycles using packaged and unpackaged instruments.
Materials And Methods:
A standard set of six orthodontic instruments were processed unpackaged through replicate 6-minute cycles with spore-strips on the top and bottom of each instrument. The spore strips were analyzed by culturing in Trypticase-soy broth for 7 days at 37 degrees C.
Results:
No sterilization failures from properly placed spore-strips were detected in any of the 18 replicate cycles. Measurements of temperatures at three chamber sites during these cycles yielded only two of 36 instances when any portion of the chamber was at a temperature below the set temperature; however, no sterilization failures occurred during either of the two cycles involved. Also, a set of four orthodontic pliers were packaged and processed through replicate 12-minute cycles with spore-strips placed inside and attached to the outside of each package. None of the total 144 spore-strips processed through six replicate cycles showed growth after culture analysis. The study demonstrated sterilization efficacy for both the wrapped and unwrapped instrument cycles using biological indicators typically used to monitor dental office sterilizers.