FOCUS ON: Hypochlorous Acid

Kevin Keane


Q: What is hypochlorous acid (HOCl)?

A: HOCl is a new disinfectant; although we say “new,” it has been known for almost 200 years since Antoine Jérôme Ballard’s discovery in 1834. In recent years, some suppliers have developed new HOCl products specifically for use in dentistry.  

In its simplest form, HOCl is generated when water and salt are passed through an electrode and a current is applied. HOCl is found naturally in the body in white blood cells. It is non-toxic and has been used as a disinfectant for many years in applications such as wound care. Its ability to remove biofilm in dental waterlines is unparalleled. 

Q: How is HOCl used in dentistry?

A: Cross contamination and pathogen infection are significant risks to patients and staff. Dentists require disinfectants that are inexpensive; safe to use; environmentally friendly, and effective within a short kill time, enabling reduced patient turnaround. A typical clinic purchases several disinfectants, including surface disinfection wipes; hand sanitizers; and dental waterline, impression, and endodontic disinfectants. HOCl can replace all of these.

Q: Where can I get HOCl?

A: You can buy bottled HOCl or buy a generator to produce your own as required. Bottled solutions are said to be less effective than freshly generated solutions and require a longer kill time than freshly generated solutions. 

There are 2 categories of onsite generators:

1. Kettle—these are cheap to purchase; however, with little control over the solutions generated, they generally produce HOCI with an extremely high chloride content that can cause corrosion. 

2. Automated—these have tight controls on the HOCl quality, pH, and chloride concentration. 

Q: Are all HOCl solutions the same?

A: No, there are many variations of HOCl on the market. If the generation process is inefficient, salt will remain unconverted in the HOCl. High chlorides cause corrosion of dental chairs, waterlines, and equipment. Many bottled solutions and solutions produced by kettle-type generators have an extremely high chloride content with as much as 18.75 g of salt per liter of HOCl. The automated generators that are designed specifically for dental applications use as little as 0.2 g of salt per liter of HOCl. To test just how much salt remains, evaporate 50 mL of any HOCl solution. Visible salt crystals remaining after evaporation indicate a high chloride content.

Q: What are the kill times with HOCl?

A: Disinfectant contact times are critical. Many chemical disinfectants require between 2 to 5 minutes to be effective, and the surface must remain wet for the contact time stated. Many alcohol-based disinfectants evaporate prior to the recommended contact time, resulting in ineffective disinfection. Ideally, the disinfectant with the shortest contact time should be used. HOCL only requires a 30-second contact time.

Q: Is HOCl safe?

A: HOCl is peer-reviewed and proven to be non-toxic. It has been used for many disinfection applications, including wound disinfection, surface disinfection, food processing, water disinfection, etc. The compounds are the same as those produced by the human immune system to defend against infection.

Q: Is HOCl environmentally friendly?

A: Onsite generators offer many environmental benefits. An improved carbon footprint through the elimination of transport and packaging of traditional chemicals and bottled HOCl is one major benefit. You can produce as much as you need when you need it. Surface disinfection using paper towels can eliminate thousands of tons of single-use wipes going to landfills. 

Q: Is HOCl compatible with dental equipment? 

A: HOCl is safe to use on your dental chairs and equipment, provided you use low chloride solutions that are produced to a precise specification. For example, dental waterline solutions should contain no more than 5 ppm chloride—that is 50 times less than the maximum amount permitted in drinking water. HOCl with a high chloride content or low pH will corrode your chair and equipment. 

Q: Why should you use HOCl in dental unit waterlines (DUWLs)?

A: Studies have shown dental chair water is frequently contaminated with large numbers of different micro-organisms (bacteria, fungi, protozoa, and viruses). Water remaining stagnant in the chair for long periods of time creates ideal bacterial and biofilm growth conditions. Microbial contamination in DUWLs has multiple sources: 

1. Water supplied to the dental unit (sterile/filtered water does not provide protection). 

2. Dental waterline tubing is not sterile, even when new.

3. The failure of anti-retraction valves. 

HOCl is peer-reviewed and regarded as one of the best DUWL disinfectants on the market because of its ability to kill biofilm.

HOCl is a safe, highly effective, multi-use disinfectant. Its genuine environmental benefits will enable you to advertise your practice as eco-friendly while offering  significant cost savings.   


Mr. Keane is the COO of Dentaqua. He has more than 30 years of experience working in automation and R&D in the medical device and pharma industries. He has more than 15 years of experience working with HOCl and holds several patents in the technology. He can be reached at or via email at