Different Disinfection Strategies in Bacterial and Biofilm Contamination on Dental Unit Waterlines: A Systematic Review

Objective: The aim of this systematic review is to explore the effectiveness of different methods of reducing contamination and biofilms in dental unit waterlines (DUWLs) and to provide reference for future standardisation of disinfection practices in dental clinic.

Methods: This systematic review searched PubMed and Web of Science databases for DUWL disinfection studies from 2013 to 2023, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and Synthesis Without Meta-analysis, additional extracting relevant data based on predefined inclusion and exclusion criteria.

Results: The study review identified 8442 articles, with 58 included after rigorous screening. Disinfection methods for DUWLs were categorised into 14 physical and 90 chemical methods. Peroxides, chloramine-based, and biguanide methods were frequently used, often in combination. The effectiveness of these methods varied; for instance, phenolic was effective, while alcohol was not, in reducing bacterial and biofilm contamination. Biguanide, when used alone or combined with chlorine-based or alcohol, showed mixed results. Chlorine-based methods, particularly when combined with quaternary ammonium salt or enzymes, were generally effective. Enzymes and iodophor also demonstrated efficacy, though with some inconsistencies. Mechanical systems, peroxides, quaternary ammonium salts, silver, and tube coatings had varying degrees of success. Other innovative methods, such as Aloe vera and slightly acidic electrolysed water, showed promise in some studies, but the effectiveness of flushing was questioned. This comprehensive analysis highlights the diversity and complexity of disinfection strategies for DUWLs.

Conclusion: Future studies should focus on how material composition and tubing design affect biofilm development and the effectiveness of disinfection methods to guide the design of advanced dental units.