Abstract: Objective To provide experimental data for finding effective cleaning methods to remove zinc oxide eugenol cement (ZOE Cement) from dental instruments with rough surfaces. Methods Dental TR-13 diamond burs were subjects of this study. The well-distribution of ZOE cement on the diamond burs’ surfaces mimicked the daily situation in clinical practice. The cleaning effects of different methods were compared by analyzing residual ZOE cement weight and its clearance rate, observing the surface of TR-13 diamond burs with scanning electron microscope. The anti-bacterial effect within a short time of different methods was also investigated. Results The TR-13 diamond burs wrapped with ZOE cement were randomly divided into four groups, including water soaking group, multi-enzyme soaking group, moisturizer soaking group and eugenol soaking group. Each group was ultrasonicated with multi-enzyme cleaning solution posterior to the soak. The cleaning effect of the eugenol soaking group was significantly better than other groups. Compared with the group processed by eugenol soak and then multi-enzyme ultrasound, the direct ultrasonic cleaning with eugenol exhibited no differences in the cleaning effect, but had poor performance in bacteriostasis. This defect would be ameliorated by multi-enzyme solution soaking after the ultrasonic cleaning. Conclusion The application of eugenol ultrasonic cleaning could clean ZOE cement contaminated dental instruments efficiently. Followed by multi-enzyme cleaning solution immersion, the proliferation of pathogenic bacteria could be inhibited effectively as well. This cleaning strategy is easy, effective and suitable for clinical application and promotion.

Key words: ZOE cement, eugenol, dental instrument, medical cleaning agent, ultrasonic cleaning, anti-bacteria