Infection control consists of a set of procedures designed to reduce the spread of microbes to, from, and among people. Many procedures are founded on very basic concepts and common sense. One of the most basic concepts related to the prevention of microbial diseases is - keep things clean.
The rationale for cleaning contaminated instruments and operatory surfaces is to remove as much of the bioburden (microbes and debris) as possible, so the subsequent steps of disinfection or sterilization will have the best chance to work. Cleaning reduces the microbial challenge and increases the chances for killing the remaining microbes. Dental materials and organic materials (such as blood and saliva) can serve to insulate the microbes from sufficient physical contact with disinfection or sterilization agents. Also, the presence of organic material can bind to and inactivate some antimicrobial chemicals, reducing the effectiveness of the killing mechanism.
The rationale for cleaning nonpatient care surfaces in the office is to present a proper (clean) look to patients. Dust and spider webs give a bad impression!
What needs to be cleaned?
Cleaning must be performed before disinfection or sterilization. This involves items used directly in a patient's mouth (instruments); items that contact something used in a patient's mouth (reusable instrument tray); or an operatory surface touched by contaminated hands and involved in the care of a subsequent patient (the dental unit light handle).
Sometimes, cleaning alone is sufficient - but only on objects or surfaces that are not directly or indirectly involved in patient care. Examples of the latter would include furnishings, floors, bracket-table arms, and any other nontouch surface in the operatory or other part of the office.
In reality, a thorough cleaning of an item or surface without subsequent disinfection or sterilization may be entirely sufficient to prevent involvement of that item or surface in the spread of disease. Unfortunately, we never know when this is true. We cannot determine (within the office) the levels of contamination (bioburden) present, except to suggest that an item is "heavily contaminated" or "slightly contaminated."
However, even a slightly contaminated object still may have a high potential for the spread of disease. This depends on the type and nature of the microbes involved and the resistance of the person to whom the microbes may spread. Sometimes, we may not even know if a surface has become contaminated. Just looking at a surface to determine if contamination has occurred is not accurate. While blood, some dental materials, and certain debris may be visible, saliva contamination is commonly invisible.
If there is a potential for an object or surface to become contaminated during treatment and that object or surface will be used during the care of a subsequent patient, then it must be considered as contaminated and be properly managed from an infection control point of view. This management must include disinfection or sterilization after the cleaning because we cannot determine how much bioburden we've actually removed.
Some have asked, "How long do microbes remain alive on operatory surfaces, and would their death eliminate the need for cleaning and disinfection or sterilization?" We can estimate this survival time in the laboratory, but, in real life, it's tremendously variable and unpredictable. Their survival is related to the environmental conditions present at the time of surface contamination (humidity, temperature, and the presence of organic material or other insulating debris). Thus, if an object or surface is considered contaminated, it must be assumed that the microbes present are alive.
The cleaning of contaminated instruments can be accomplished by using ultrasonic cleaners, instrument washers, or washer/disinfectors. This equipment comes in various sizes to match the needed cleaning capacity of any office. Be sure to purchase appropriate racks and baskets, which usually facilitate cleaning by keeping instrument cassettes or even loose instruments separated and easy to remove after cleaning. Also, use a dental/medical instrument cleaning solution in this equipment. Common detergents may not contain the proper ionic strength, pH, rinsability factors, or rust inhibitors.
Hand-scrubbing is not recommended for routine instrument cleaning. While it can be effective, it is too dangerous and may increase the risk of instrument punctures. Also, remember that cleaned instruments are not sterile. If they are handled before packaging and sterilization, it must be done with gloved hands or forceps.
The cleaning of contaminated surfaces before disinfection is very important. This cleaning removes much of the bioburden on the surface so that, when the disinfectant is applied, it won't be overwhelmed by the contaminating material. Unfortunately, we can't monitor how effective our disinfection procedures are, so we must perform the procedure in a way to best assure success. This means cleaning first and then disinfecting.
In summary, cleaning is basic to achieving infection control.
Chris H. Miller, PhD, is professor of oral microbiology and executive associate dean at the Indiana University School of Dentistry.
