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In most dental practices, instruments are cleaned in an ultrasonic cleaner. This type of unit removes bioburden by using sound waves generated by electrical energy.
As the sound waves move through the liquid cleaning solution, they cause the formation and bursting of millions of small bubbles. This “cavitation” process functions by disrupting chemical bonds, which hold the debris on instrument surfaces. This facilitates cleaning.
Only solutions that are formulated specifically for ultrasonic cleaners are to be used. The resulting cleaning of contaminated instruments is more efficient as compared to hand scrubbing with a scrub brush. Cleaning solutions also should be changed at least daily, or more frequently if visibly contaminated.
For many years, available ultrasonic solutions were detergent-type cleaners only. These worked by emulsifying oil and water, sometimes leading to formation of an oil film on the surface.
In the 1960s, a new generation of enzymatic cleaners became available in various industries. When used in commercial laundry detergents, the addition of enzymes increased the capability of the products to clean. It was not until much later that enzymatic detergent cleaners became available for dental facilities.
Enzymatic cleaners and instrument presoaks (i.e., holding solutions) are specifically formulated to loosen debris. Initially, the enzymatic ultrasonic cleaners contained a single proteolytic enzyme (a protease).
By having the ability to facilitate breakdown of adherent proteinaceous material (blood and saliva) into water-soluble components, these preparations were shown to efficiently clean difficult-to-remove debris from instruments.
Repeated studies demonstrated that they are able to dramatically reduce the need, if any, for hand scrubbing of instruments. Virtually all cleaning solutions designed for use in an ultrasonic unit contain at least one proteolytic enzyme.
As one might expect, enzymatic activity in a cleaner decreases with frequent use during the day, thereby diminishing the capability of the protease to break down and remove organic material. Thus, it is recommended that these cleaning solutions be changed daily, or sooner, if visibly contaminated.
In an effort to further enhance removal of biological debris prior to sterilization, a later generation of cleaning agents has been developed that can be classified as dual-enzymatic cleaners. Inclusion of a second active component increases the ability of the cleaner to remove adherent contaminated material on instrument surfaces faster than a single-enzyme cleaner.
Both the single- and dual-enzymatic preparations share similar features. These include function at or near neutral pH, low foaming, biodegradable spent solution for end disposal down a sink, phosphate-free, nonammoniated, and chlorine-free.
Research and development in this area have not ceased. One of the latest innovations is designed to target proteinaceous and nonprotein-containing contamination.
Ultrasonic cleaners addressing this issue still are classified as dual-enzymatic. But instead of containing two proteolytic enzymes, this type of cleaner uses one protease and an amylase. The latter enzyme adds an important additional decontaminant because of its ability to break down carbohydrate-containing organic debris.
Why is this important?
The most common forms of adherent debris on instruments, blood, saliva, and plaque contain carbohydrate components. Now an enzymatic cleaner can specifically enhance their degradation.
In thinking about historical recommendations for instrument cleaning, many of you might remember when early products for dental ultrasonic units contained only detergents. After enzymatic cleaners were introduced, clinical personnel asked which type was better at removing debris.
While both are able to clean, there is no doubt that the evolution of subsequent generations of cleaning agents has increased their efficacy. Check the label of the product you use, evaluate how effectively it cleans, and then judge for yourself.
Dr. John A. Molinari is director of infection control for THE DENTAL ADVISOR. Previously, he was professor and chairman of the Department of Biomedical Sciences at the University of Detroit Mercy School of Dentistry. Contact him at
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