# Evaluation of Safety of Disposable Saliva Ejectors after Autoclaving Sterilisation

## TL;DR

This study shows that even after sterilization, some saliva ejectors used in dentistry still have bacteria and proteins, which could lead to cross-contamination if reused.

## Contribution

This is the first experimental study to demonstrate the risks of reusing sterilized saliva ejectors in dental practices.

## Key findings

- Residual bacteria (Staphylococcus warneri) were found in 1.64% of sterilized saliva ejectors.
- Residual proteins were observed on the tips of 81.8% of samples and on all bodies of saliva ejectors.
- The presence of bacteria and proteins suggests that reusing saliva ejectors can cause cross-contamination.

## Abstract

To identify the bacteria and proteins that remain after cleaning and sterilisation of SEs used in dental practices, and to investigate potential problems when reusing SEs.

In total, 105 SEs used on study participants were collected. The collected SEs were immediately immersed in the disinfectant solution and then washed with tap water and a cleaning brush. The SEs were dried, placed in sterile pouches, and sterilised in an autoclave before being used in the experiment. To detect residual bacteria, SE samples were cultured in brain heart infusion (BHI) broth for 10 days, followed by re-culturing on blood agar and BHI agar. Bacterial identification was performed using bacterial colonies. To identify residual proteins, SE samples were stained with phloxine B, and the stained sites and area were analysed.

Residual bacteria were found in one (1.64%) of 61 sterilised SEs. The cultured colonies were identified as Staphylococcus warneri. Residual proteins were observed on the tips of 36 (81.8%) of the 44 SE samples, and on the bodies of all samples (100%). The average stained area of the residual proteins on the SE bodies was 1.78% (standard deviation, 3.1%).

The presence of bacteria and proteins in sterilised SEs indicates that their reuse can cause cross-contamination. This study is the first attempt to provide experimental evidence of the problems with reuse of SEs.