Title Adding Sodium Hypochlorite to Dental Unit Waterlines Can Reduce Bacterial Spread from Aerosols Generated by Endodontic Procedures
Clinical Question For teeth undergoing endodontic treatment, does adding sodium hypochlorite in the dental unit water lines (DUWL) reduce bacterial load from aerosols, compared to DUWL without sodium hypochlorite?
Clinical Bottom Line Due to the COVID-19 pandemic, dental clinics have been prudent about PPE use and on adopting various precautions to reduce aerosols generated by dental procedures. One cannot eliminate the generation of aerosols, but one can try to reduce bacterial load and spread by adding a biocide such as 0.1% sodium hypochlorite to dental unit waterlines. This can be a measure dental clinics can adopt to reduce the spread of contaminated aerosols during dental procedures, and possibly lead the way to reduce viral spread as well.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
36030970Rayyan/2022Phase I: 38 samples; Phase II: 30 samples.Randomized Controlled Trial
Key resultsThe endodontic procedures being measured for aerosol generation and bacterial contamination were vital pulp therapy (VPT), non-surgical root canal therapy (NSRCT), surgical RCT (SRCT), and incision and drainage (I&D). Phase I: VPT (n=10), NSRCT (n=10), SRCT (n=10), I&D (n=8) Phase II: VPT (n=10), NSRCT (n=10), SRCT (n=10). All endodontic procedures in this study generated contaminated aerosols. Aerosols could travel as far as 10 feet. The procedure that produced the most aerosolized contamination was VPT with full pulpotomy. The addition of 0.1% sodium hypochlorite in the DUWLs reduced the bacterial load collected on the agar plates, as compared to the agar plates that were contaminated with aerosols with no 0.1% sodium hypochlorite in the DUWLs.
Evidence Search Sodium hypochlorite and waterlines and aerosols
Comments on
The Evidence
This study is the first of its kind to evaluate the effect of adding a biocide such as sodium hypochlorite into the DUWLs on the bacterial load in aerosols produced during dental procedures, specifically endodontic procedures. In phase II of the study that is relevant to the PICO question, endodontic procedures were performed with and without 0.1% sodium hypochlorite in the DUWL. Aerosols were collected by the passive sampling technique by placing agar plates in predetermined locations. Aerosolized bacteria in the form of colony forming units (CFUs) were evaluated and compared to the baseline samples. The study showed that aerosolized particles can travel as far as 10 feet from the patient’s head; all procedures generated aerosolized bacteria. When comparing the agar plates with treated DUWLs to the non-treated DUWLs, there was a significant reduction in CFUs from samples collected from procedures treated with 0.1% sodium hypochlorite in DUWL. Being the only study to do this, more prospective randomized controlled studies need to be done to strengthen the validity of this study and future studies.
Applicability This study limited its evaluation of aerosol generation and contamination load to only endodontic procedures. However, the use of high-speed hand pieces, ultrasonics, and other aerosol generating instruments is common across all dental specialties. The purpose of the study was to see if adding 0.1% sodium hypochlorite to DUWLs would reduce bacterial load in generated aerosols in a clinical setting; this study showed that. Due to the recent Covid-19 pandemic, dental professionals are trying to provide a safe working environment for their patients and staff. They want to reduce the possibility of any transmissible bacterial, fungal, or viral infection. Dental procedures generate substantial amounts of aerosolized particles, and with this novel measure in adding a biocide component to the DUWL, can help reduce the infectious potential of aerosols. Sodium hypochlorite is a commonly used and effective antibacterial agent. At 0.1% concentration, it is known to be safe to mucosal membranes and non-corrosive to waterline pipes and tubing. When sodium hypochlorite interacts with water, it forms hypochlorous acid and hypochlorite ion, which are effective against bacteria, viruses, and fungi. The study limited itself to evaluating the growth of aerobic bacteria on the agar plates and did not evaluate the spread of aerosolized viral particles and the efficacy of 0.1% sodium hypochlorite on reducing viral load. This can be a promising area to explore in future studies.
Specialty (Endodontics)
Keywords Sodium hypochlorite, dental unit waterlines, aerosols, endodontics
ID# 3507
Date of submission 11/26/2022
E-mail huynhc1@livemail.uthscsa.edu
Author Dr. Cindy Huynh, DDS
Co-author(s) Dr. Jaret Simonsen, DMD
Co-author(s) e-mail simonsen@livemail.uthscsa.edu
Faculty mentor Dr. Nikita Ruparel, MS, DDS, PhD
Faculty mentor e-mail ruparel@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available