Effect of Lubrication on Sterilization of Dental Handpieces

Many of the devices sterilized in health care facilities contain lumens and other areas that are difficult to penetrate by sterilization processes. It is generally accepted that in steam sterilization, the dental handpiece provides the most difficult challenge to sterilant penetration (ANSI/AAMI ST55:2003 5.5.5.1 Handpiece selection). However, current standard methods do not specify a standard handpiece for testing nor a requirement to lubricate the handpiece turbine prior to steam sterilization. Objectives: In this study we evaluated the efficacy of the steam sterilization of dental high speed handpieces in the presence or absence of handpiece lubricant as specified by the handpiece manufacturer. Methods: Three different brands of handpieces were used. Sterilization tests for handpieces were performed by inoculating lubricated or non-lubricated turbines with spore suspension in blood containing 1.0 x 106 Geobacillus stearothermophilus. After steam sterilization of handpieces, turbines were aseptically transferred and incubated in tryptic soy broth (TSB) for 7 days at 55oC. Results: According to ANSI/AAMI ST55:2003 4.5 Biological performance of sterilizers, biological indicators processed in half cycles shall show no growth of the test spores. In this study, no live spore growth was observed from lubricated handpiece turbines sterilized by three commercially available tabletop steam sterilizers. Spore germination occurred in all non-sterilized positive controls, and no growth was detected in negative controls (sterile TSB). However, 18.5 ± 7.4 (SEM) % of non-lubricated handpiece turbines demonstrated spore growth. Conclusions: This study demonstrates that the lubrication of handpiece turbines with the manufacturer's recommended lubricant enhances the sterilization efficacy. Specification of handpiece turbine lubrication should be considered for any standard method used for testing the efficacy of steam sterilizers used in dentistry. More research is needed to identify the cause or causes of this lubricating effect. This study was funded by ADA.