A previous study has demonstrated that canister-style turbines may have a higher chance of failing the performance standard for AAMI ST55 than those containing open wheel-style turbines without lubricant. However, no live spore growth was observed after tabletop steam sterilization when the turbines were treated with lubricant (JDR 2008, 87 (Special Issue): #0937). Lubrication helps to expel debris and extends the useful life of a handpiece during repeated autoclave cycles. Most lubricants are non-toxic; however, it is not clear if lubricant is harmful to bacterial endospores.
Objective: Evaluate the effect of dental handpiece lubricant on bacterial endospore germination.
Methods: Three different brands of lubricant were used. Spore germination was assessed with and without lubricant in 96-well plates with spore suspension in 10% blood containing 106 Geobacillus stearothermophilus spores. The inoculum was dried in each well overnight at 37o C. Amount of lubricant per well was 0, 10, 50, and 100 uL. Spore contact time with lubricant was 0, 30, 60 minutes and 18 hours, followed by replacement and incubation with TSB. Similarly, handpiece turbines were inoculated with 107 spores in blood and allowed to dry, followed by gently dipping each inoculated turbine in lubricant and draining the excess. Spore germination in lubricated and non-lubricated groups was compared by measuring optical density at 570 nm (plates) or by counting CFUs on TSA (turbines).
Results: Spore growth in 96-well plates demonstrated no significant difference in optical density between non-lubricated and lubricated groups, regardless of amount or contact time with lubricant. Non-lubricated and lubricated turbines showed spore recovery of (6.67 ± 0.80) x 106 and (6.20 ± 0.49) x 106 spores, respectively, from spore inocula of 107 spores per turbine.
Conclusion: This study demonstrates that three handpiece lubricants did not prevent or inhibit germination of Geobacillus stearothermophilus endospores.