Exploring sterilizer performance through external biological indicator testing: a retrospective study

Quality assurance policies mitigate the risk of nosocomial infections from dental office instrument sterilization by assessing sterilizer performance through biological indicator (BIs) testing. This study aimed to evaluate the prevalence of failed sterilization cycles and their causes of failure for a period of eight years through database analysis of a quality assurance laboratory in the province of Saskatchewan, Canada.

A database of BIs (n = 198,771) performed by an independent quality assurance laboratory from 2015 to 2022 was analyzed. Dental offices (n = 362) inserted Sporview^® Biological Sterility Indicators strips in full sterilizer loads and mailed the processed BI tests to an external quality assurance laboratory for analysis. Samples were assessed based on a colorimetric method checking for changes in color and turbidity. Data was collected and statistical analyses were performed using IBM SPSS 28.0.

The overall failure rate throughout the study was 0.20%, and it decreased gradually from 0.51% (2015) to 0.15% (2022). On average, retests were conducted within 2 days of failure notification. The preferred method of processing was steam sterilization (98%), which had a steadily increasing utilization over time and displays a statistically lower failure rate (0.20%) as opposed to dry heat (1.30%) and chemical vapour (1.40%) sterilizers. Most BI failures were attributable to human error (91.80%), and equipment failures were significantly more likely to occur with dry heat or chemical vapour sterilizers (p < .001).

This study significantly contributes to the understanding of dental sterilizer performance in Canada. The low and decreasing sterilizer failure rates over the study period indicate safe dental office procedures and reduced potential for disease transmissions. The study highlights the effectiveness of steam sterilizers with remarkably low failure rates, while human error remains the primary cause of failures. Further research should focus on identifying factors leading to human error and interventions to minimize sterilization failures in dental settings.