Surface barriers

Jan. 1, 2000
Here are some ways to minimize both environmental surface contamination and operatory turnaround time.

Here are some ways to minimize both environmental surface contamination and operatory turnaround time.

In the 1970s, Dr. James Crawford published his landmark infection-control study exploring the premise "if saliva were red." Using red poster paint to simulate saliva, practitioners dipped their fingers into the paint and began normal clinical treatment on patient mannequins. The paint subsequently "contaminated" an array of operatory surfaces during the course of the mock treatment, demonstrating the cross-contamination that occurs from a practitioner`s saliva-covered fingers.

An expanded study by Glass, Cottone, and Leuke at the University of Texas in San Antonio resurrected the poster-paint concept to mark contamination from spatter during a simulated lower second-molar operative procedure using a high-speed handpiece and water coolant. In addition to contaminating the protective clothing of the dentist and assistant, the high-volume evacuator became laden with intraoral fluids.

In a study by Molinari and York at the University of Detroit Mercy, secretions were transferred from the gloved hands of the clinical staff to the patient charts, the instrument tray, various hand instruments, the air/water syringe, and the unit light handle.

Although there has been no documented evidence of disease transmission in dentistry via contaminated surfaces, the theoretical possibility exists. Different microorganisms have a wide range of survival times on environmental surfaces. Laboratory studies indicate that Mycobacterium tuberculosis can remain viable for weeks, whereas the herpes simplex virus dies in a matter of seconds to minutes.

Survival times of microorganisms are affected by a range of environmental conditions such as humidity, temperature, the presence of nutrients, and physical protection from surface disinfectants by fomites. These variables preclude an accurate prediction of how long any microorganism might survive on a dental office surface. The safest approach is to assume that surfaces have been contaminated with blood or other potentially infectious materials. Assume the surfaces harbor live microorganisms that must be removed or killed before the surface is used again in the treatment of the next patient.

The two approaches to maintaining surface asepsis in dentistry are disinfection (following thorough surface precleaning) and barrier protection. This month`s article looks at barrier protection as a way to minimize both environmental surface contamination and operatory turnaround time.

The rationale

Consistent with a basic tenet of infection control - to limit contamination whenever possible - environmental surface barriers offer a time-saving alternative to between-patient cleaning and disinfection of operatory surfaces. The concept is to place a fluid-impervious barrier on surfaces prone to contamination before potentially infectious materials can be introduced through contact with contaminated gloves, instruments, splash, or spatter. As long as the barrier remains intact, the surface it protects remains free of patient materials. Barriers are simply changed between patients, potentially limiting environmental surface cleaning and disinfection to an end-of-the-clinic-day ritual.

Commercial surface covers are available in a variety of shapes and sizes and are often cut to fit the instrument or equipment they protect - air/water syringe handle covers, hose covers, pen sheaths, etc. They generally are made of clear plastic supplied as wraps, bags, or tubes, or as plastic-backed paper. Some barriers contain a mild adhesive on one side to keep them in place on the surface; others might use a drawstring closure to secure the cover; and some plastics "cling" when placed in contact with a smooth surface. In selecting environmental surface barriers, the primary feature is impermeability, and any material manufactured and advertised as a surface barrier should be supplied with evidence of the impermeable nature of the product.

Although presized and precut barriers may save time and offer added convenience, the American Dental Association and the Occupational Safety and Health Administration state that clear plastic food wrap/bags or aluminum foil also afford appropriate protection, often at a lower cost. Patient bibs made of plastic-backed paper also can double as an environmental surface barrier to preclude some of the handling issues of plastic wrap for flat operatory surfaces, although this may not be the most economical option. To reduce costs, thin (rather than thick) plastic sheets or bags can be used as long as they are not punctured by the surface or instrument being covered.

The procedure

Barriers generally are applied before surfaces have the chance to become contaminated. They are placed on clean surfaces prior to seating the patient. If the surfaces to be covered are contaminated, preclean and disinfect the surface, preferably using a water-based detergent/disinfectant and the "spray-wipe-spray" technique, then remove gloves, wash and dry hands, and place a fresh surface cover. Ensure surfaces are completely dry before placing the barriers; this will minimize corrosion, material breakdown, and surface discoloration from extended contact with chemical disinfectants.

Place each cover so that it protects the entire surface and does not come free when the surface is touched.

Following patient treatment and with personal protective equipment in place (the examination gloves used in patient care provide sufficient protection when removing surface barriers), carefully remove each surface cover without contacting the underlying surface. If a surface is touched during barrier removal, it should be precleaned and disinfected before a clean barrier is placed. Use particular care when removing foil covers, as the sharp edges tend to tear gloves.

Discard used surface barriers with the regular office waste unless local laws designate these items as regulated waste. In most states, nonsharp contaminated waste (such as surface covers) is not classified as regulated waste unless an item is soaked or caked with blood or other potentially infectious material that would be released if the item were compressed.

Remove and discard contaminated examination gloves, wash hands, and apply fresh surface barriers for the next patient.

Easy to use and available in a variety of sizes, clear plastic bags can be used to cover much of the larger equipment and furniture in the operatory, including most touched surfaces (headrest, control panel) of the dental chair. A bag also can be placed on the bracket table to cover both the table and the handpiece control unit. Wraparound chair backs of operator seating often are touched during patient treatment; these seatbacks also lend themselves to simple protection with a large plastic bag. Hoses and connectors are easily covered with plastic tubing secured with tape or a rubber band at the connector. Alternatively, a narrow, long plastic bag may be forced over the connector end.

Light handles and switches are routinely touched during the course of patient treatment. Although some operatory lights have removable handles that can be cleaned and sterilized before reuse, barrier protection may be the simpler option. Covering the air/water syringe handle with plastic wrap prevents contamination with less time and energy than attempting to adequately clean and properly disinfect around the buttons that can harbor debris. X-ray unit tubeheads and control panels also lend themselves to barrier protection, as do the faucets in manually controlled sinks.

The pros and cons

For uncovered surfaces prone to contamination during dental procedures, between-patient disinfection is necessary to prevent cross-contamination. Although this option eliminates the direct cost associated with the use of surface barriers, between-patient disinfection may actually increase infection-control costs when viewed in the context of added staff time and higher operatory turnaround intervals. Staff must don not only gloves, but also protective eyewear and masks when chemically disinfecting an operatory, and many of the chemicals used for disinfection can be damaging to upholstery and other environmental surfaces. Furthermore, some surfaces cannot be precleaned adequately to ensure effective disinfection. (Note: Electrical switches should not be sprayed with disinfectant, as it can cause short-circuiting. An adhesive barrier is recommended, if necessary.)

Although barrier protection offers a simple, effective way of preventing contamination, it is not without its disadvantages. A variety of sizes and types of surface covers may need to be purchased and stocked. Covering surfaces also adds nonbiodegradable plastic to the environment and may leave the operatory looking less esthetic, despite minimizing the handling, storage, and powerful odors associated with chemicals for disinfection. Nonetheless, because of the time saved by covering surfaces that are difficult to adequately clean, most practices opt to use barriers for at least some of their operatory surfaces. For surfaces that are difficult and time-consuming to adequately clean, infection-control experts encourage the use of protective barriers for touch and transfer surfaces.

According to infection-control educators and consultants, however, surface asepsis is an area prone to "infection-control overkill." Surfaces that are barrier-protected during treatment need not be disinfected after each patient. As long as the barrier remains intact, the contaminated covering simply can be removed and replaced. At the end of each clinic day (and following any contact between the surface and blood or other potentially infectious materials, for example, via tears or punctures in the barrier), precleaning and disinfection are appropriate. The following work-day morning, fresh barriers can be placed with clean hands prior to patient treatment.

Whether practices elect to use between-patient disinfection, protective surface coverings, or a combination of both, the goal remains the same: to maintain asepsis to further reduce the already-low risk of disease transmission from contaminated dental operatory surfaces.

This resource was reprinted with the permission of OSAP. OSAP is a nonprofit organization providing information and education on dental infection control and office safety. For more information, please call (800) 298-6727.

Classification and management of environmental surfaces

To determine which surfaces need to be covered, consider the system outlined in OSAP`s 1997 infection control in dentistry guidelines:

Touched surfaces are usually contacted and contaminated by staff during dental procedures. Examples of touched surfaces include the X-ray exposure button, dental chair switches/headrest, and the air/water syringe. These surfaces require either between-patient cleaning/disinfection or protection with an impervious, single-use barrier.

Transfer surfaces are not touched directly by the dental worker, but are usually contacted by contaminated instruments. Examples of transfer surfaces include instrument trays or bracket tables. For optimal asepsis, these surfaces should be maintained in the same manner as touched surfaces.

Splash, spatter, and aerosol surfaces comprise all surfaces in the operatory not classified as touched or transfer surfaces. Examples include the X-ray view box and any unused countertop areas. Splash and spatter surfaces need not be disinfected, but should be cleaned at least daily.

Using surface covers: step-by-step procedures

1. Apply appropriate surface covers before environmental surfaces have the chance to become contaminated with patient material. (If the operatory surface to be covered has been previously contaminated, preclean and disinfect the surface, then remove gloves and wash hands before applying the surface cover.)

2. Place each surface barrier so that it protects the entire surface and does not dislodge when touched.

3. Wear protective gloves when removing surface barriers following patient care.

4. Remove contaminated covers from touch-transfer surfaces, using care to avoid touching the underlying surface. If a surface is touched during removal of a cover, preclean and disinfect the surface.

5. Discard used covers into the regular office trash unless local laws classify these items as regulated waste, in which case they must be disposed of as indicated by local laws. (In most states, nonsharp contaminated waste is not categorized as "regulated waste" unless an item is soaked or caked with blood or other potentially infectious material that would be released if the item were compressed.

6. Remove and discard contaminated gloves, wash hands, and apply fresh surface covers for the next patient.

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