The effectiveness of two sterilization methods when different precleaning techniques are employed

The effectiveness was investigated of methods for the preparation of dental handpieces prior to sterilization procedures utilizing ethylene oxide (ETO) gas. The handpieces were cleaned using either a forced-air purging unit (group 1) or by flushing with air and water from the dental unit (group 2). They were inoculated with either Bacillus subtilis or Streptococcus mutans. After exposure to either steam or ETO gas, the handpieces were flushed with saline and the viability of recovered bacteria assessed. No viable bacteria were recovered from group 1 handpieces treated with either ETO gas or steam. However, viable S. mutans were recovered from group 2 handpieces following exposure to ETO gas. Thus, the use of a high-pressure forced-air purging unit may be required for the reliable sterilization of dental handpieces by ETO gas, as viable S. mutans could be recovered from untreated handpieces exposed to ETO gas.