A new methodology for decontamination of dental instruments by an ultrasonic cleaner based on Sweep System Technology

The efficiency of a decontamination procedure by sonication for different dental instruments after experimental microbial and viral contamination was tested. Both germicidal and virucidal activity of sonication in the presence or absence of a cationic bio-biguanid disinfectant was assessed following three different disinfection/sterilisation protocols. Dental instruments were contaminated with a mixed culture of Enterococcus faecium, Staphylococcus sp., Pseudomonas aeruginosa, Mycobacterium sp., Escherichia coli and Bacillus subtilis, or with Poliovirus type 1 and Herpesvirus simplex type 1 (HHV-1), exposed to ultrasonic treatment in an ultrasonic bath and the surviving microorganisms titered. The results showed that an effective disinfection of dental instruments, expressed by an equal or higher than 4 logs microbial and viral reduction, can be obtained after 15 min or 10 min sonication in an ultrasonic cleaner equipped with a Sweep System Technology. Conversely, by the combined action of chemical disinfection and ultrasonic treatment in the same device, a sterilising effect was obtained after only 5 min for microbial and 10-15 min for virally contaminated instruments. The synergistic effect of chemical and physical means, as already accepted as an effective cleaning procedure of medical instruments, can therefore be applied to obtain a safe and effective sterilisation of dental instruments potentially contaminated by organic fluids and dental material harbouring pathogenic microbes and viruses.