Surface decontamination in theory and practice

In the dental surgery, any surface or equipment that does not come in direct contact with patients is designated as an environmental surface. Environmental surfaces are further categorised as housekeeping or clinical contact surfaces based on the risk for contamination[i].

Housekeeping surfaces are surfaces not frequently touched during dental treatment, such as floors, countertops, sinks and walls.

Clinical contact surfaces are any surfaces that that might be directly contacted or touched and become contaminated with blood or other potentially infectious materials by gloved hand, aerosol, contaminated instruments or other items in the course of providing dental care[ii].

Examples of clinical contact surfaces include: light handles, chair control buttons, X-ray equipment, computer keyboards, handpiece hoses, headrests and reusable containers of dental materials.

An effective way to protect some clinical contact surfaces from contamination is to use disposal plastic barriers designed to fit over frequently touched surfaces such as light handles, control panels and headrests. These should be removed and discarded after each patient.

The problem of surface contamination

The risk of infection from inadequately cleaned and disinfected surfaces is high and can serve as a reservoir for bacterial, fungal, and viral pathogens that can persist on inanimate surfaces for considerable periods of time, for example:

• Clostridium difficile (C.diff gastroenteritis) > 5 months
• Herpes simplex (cold sores) > 8 weeks
• MRSA (various) > 7 months
• Rhinovirus (common cold) > 7 days
• Streptococcus pyogenes (Strep throat) > 6.5 months[iii]

Microorganisms can spread during dental procedures following the dispersion of aerosols and splatter and pathogens can be transmitted via blood and saliva transferred onto surfaces surrounding the treatment area.

Used instruments placed on work surfaces can cause contamination, as well as touching surfaces with contaminated gloved hands. Areas around the spittoon can also be a risk area from bodily fluid contamination[iv].

A significant potential infection route within the practice is hand to surface and hand to patient contact. Surfaces that are frequently touched in waiting rooms and surgeries (for example, door handles, light switches and shared equipment) can easily become contaminated with microorganisms, posing a possible infection risk.

Surface cleaning protocols

Preventing the spread of infection remains a number one priority for dental practices to protect both patient and staff from the danger of exposure to harmful pathogens. This can be achieved through hand hygiene, the use of personal protective equipment (PPE) and surface cleaning and disinfection.

The patient treatment area should be cleaned and disinfected after every session, even if the area appears uncontaminated. Areas to be cleaned and disinfected include:

Between patients:

• Work surfaces local to dental chair and decontamination areas
• Dental chairs
• Curing lamps
• Inspection lights and handles
• Manual controls (including replacement of covers)
• Trolleys/delivery units
• Spittoons, aspirators and X-ray units

Daily / End of session:

• All work surfaces
• Taps and sinks
• Drainage points
• Splashbacks
• Walls and mirrors
• Cupboard doors
• Floor

Weekly:

• Window ledges and blinds
• Accessible ventilation fittings
• Accessible surfaces such as shelving, radiators and shelves in cupboards

One-stage vs. two-stage decontamination

The first stage in the decontamination process is cleaning the surface. The disinfection process is compromised if the surface is not adequately cleaned first, therefore both cleaning and disinfection are required.

Cleaning is the removal of visible soil (e.g., organic and inorganic material) from objects and surfaces and is normally achieved manually or mechanically using water with detergents or enzymatic product. Incomplete removal of dust, dirt, and organic matter will interfere with the effectiveness of the chemical disinfectant by protecting the pathogen from adequate exposure to the disinfectant or reducing the antimicrobial activity of the disinfectant[v].

Disinfection refers to the inactivation of pathogens, a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects and surfaces.

Products that accomplish both cleaning and disinfection in one application offer a more efficient ‘one-stage’ approach and is effective in most clinical applications. However, the chemical composition of some disinfectants prevent them from being good cleaners and require pre-cleaning followed by disinfection, hence a two-stage approach.

Alcohol is a good disinfectant but is not effective as a cleaner. If proteins are present and an alcoholic solution is used, proteinaceous material can be fixed to the surface, potentially trapping microorganisms and providing additional surface roughness to aid adhesion of further soiling.

The adverse effect that a disinfectant has on dental equipment such as chair upholstery, vinyl surfaces etc., is also an important consideration when choosing a product. Users should check the manufacturer’s label for surface compatibility of any chemical agent before application to the various surfaces across the dental practice.