Autoclaving of lubricated dental instruments

Test organisms forced mechanically into lubricated, rotating dental instruments (handpieces) were all killed during autoclaving at 134 degrees C for 8 min, even when protected by serum and oil. The test organisms were: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and spores of Bacillus stearothermophilus. Also when testing the sterility of autoclaved simulated instrument surfaces (brass cylinders and pieces of a cotton fabric) which had been inoculated with bacteria and dried before they were sprayed with oil, there was no growth of the test organisms. In addition to the other test organisms, spores of Bacillus subtilis and Gram-positive, anaerobic bacteria isolated from used handpieces that had been exposed to several autoclavings were used. Some of the handpieces that had been left to dry after use in the dentist's office before they were autoclaved, were shown not to be sterile. Therefore, the authors suggest that autoclaving of the instruments should take place shortly after use and prescribed cleaning.