During patient treatment, dental equipment and treatment room surfaces are likely to become contaminated with saliva or aerosol containing blood and saliva. Surfaces that are touched frequently (e.g., light handles, unit controls, drawer handles) can act as reservoirs for microorganisms. When these surfaces are touched, microbial agents can be transferred to instruments; to charts; or to the nose, mouth, or eyes of dental team members or of other patients. A primary source of cross-contamination can be seen when a member of the dental team touches surfaces with contaminated gloved hands.

Laboratory studies have determined that microorganisms may survive on environmental surfaces for different lengths of time. For example, Mycobacterium tuberculosis may survive for weeks, whereas the herpes simplex virus dies in a matter of minutes. It is impossible to predict accurately the life span of microorganisms on the surfaces of dental equipment. Therefore, the safest approach for avoiding contamination is to assume that if the surface has had contact with saliva, blood, or other potentially infectious material, live microorganisms are present.

Note: Throughout this chapter, recommendations of the Centers for Disease Control and Prevention (CDC) are indicated, and the category of scientific evidence is noted at the end of each recommendation.

Rankings of Evidence

Each recommendation made by the CDC is categorized on the basis of existing scientific data, theoretical rationale, and applicability. Rankings are based on the following categories:

Category IA	Strongly recommended for implementation and strongly supported by well-designed experimental, clinical, or epidemiologic studies (studies of patterns and causes of diseases)
Category IB	Strongly recommended for implementation and supported by experimental, clinical, or epidemiologic studies and a strong theoretical rationale
Category IC	Required for implementation, as mandated by federal or state regulation or standard
Category II	Suggested for implementation and supported by suggestive clinical or epidemiologic studies or a theoretical rationale
Unresolved Issue	No recommendation. Practices for which insufficient evidence or no consensus regarding efficacy exists.

CDC Recommendations for Environmental Infection Control

General Recommendations

Follow the manufacturers’ instructions for correct use of cleaning and EPA-registered hospital disinfecting products. (IB, IC)

Do not use liquid chemical sterilants/high-level disinfectants for disinfection of environmental surfaces (clinical contact or housekeeping). (IB, IC)

Use PPE, as appropriate, when cleaning and disinfecting environmental surfaces. (IC)

Clinical Contact Surfaces

Use surface barriers to protect clinical contact surfaces, particularly those that are difficult to clean, and change barriers between patients. (II)

Clean and disinfect clinical contact surfaces that are not barrier protected by using an EPA-registered hospital disinfectant with low-level (i.e., HIV and HBV label claims) to intermediate-level (i.e., tuberculocidal claim) activity after each patient. Use an intermediate-level disinfectant if visibly soiled with blood. (IB)

Housekeeping Surfaces

Clean housekeeping surfaces (e.g., floors, walls, sinks) with a detergent and water or an EPA-registered hospital disinfectant/detergent on a routine basis, depending on the nature of the surface and the type and degree of contamination, and as appropriate according to location within the facility, and when visibly soiled. (IB)

Clean mops and cloths after use and allow to dry before reuse, or use single-use disposable mop heads or cloths. (II)

Prepare fresh cleaning or EPA-registered disinfecting solutions daily and as instructed by the manufacturer. (II)

Clean walls, blinds, and window curtains in patient care areas when they are visibly dusty or soiled. (II)

EPA, Environmental Protection Agency; HBV, hepatitis B virus; HIV, human immunodeficiency virus; PPE, personal protective equipment.

Environmental Infection Control

The CDC Guidelines for Infection Control in Dental Healthcare Settings—2003 divide environmental surfaces into clinical contact surfaces and housekeeping surfaces. Housekeeping surfaces include floors, walls, and sinks. Because these have a much lower risk for disease transmission, cleaning and decontamination techniques are not as rigorous as those used for clinical areas and for patient treatment items.

Things to consider when one is planning for cleaning and disinfection of patient treatment areas include the following:

• Amount of direct patient contact

• Type and frequency of hand contact

• Potential amount of contamination by aerosol and/or spray

• Other sources of microorganisms (e.g., dust, soil, water)

Clinical Contact Surfaces

Clinical contact surfaces can be directly contaminated by direct spray or spatter generated during dental procedures, or by contact with the dental professional’s gloved hands.

Current infection control guidelines of the Organization for Safety and Asepsis Procedures (OSAP) recommend that clinical surfaces should be classified and maintained under three categories: (1) touch, (2) transfer, and (3) splash, spatter, and droplet (Fig. 20-1).

FIG. 20-1 Touch surfaces *(A);* transfer surfaces *(B);* and splash, spatter, and droplet surfaces *(C)*.

Touch surfaces are directly touched and contaminated during treatment procedures. Touch surfaces include dental light handles, dental unit controls, chair switches, chairside computers, pens, telephones, containers of dental materials, and drawer handles.

Transfer surfaces are not directly touched but often are touched by contaminated instruments. Transfer surfaces include instrument trays and handpiece holders.

Splash, spatter, and droplet surfaces do not actually contact members of the dental team or contaminated instruments or supplies. Countertops are a major example.

Touch and transfer surfaces should be barrier protected or cleaned and disinfected between patients. Splash, spatter, and droplet surfaces should be cleaned at least once daily (Table 20-1).

TABLE 20-1

Comparison of Surface Barriers and Precleaning/Disinfection

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	Advantages	Disadvantages
Surface barrier	Protects surfaces that are not easily cleaned and disinfected	Adds plastics to the environment after disposal May be more expensive than precleaning and disinfecting Requires a variety of sizes and shapes May become dislodged during treatment
	Prevents contamination when properly placed
	Less time consuming
	Reduces handling and storage of chemicals
	Provides patient with visual assurance of cleanliness
	Does not damage equipment or surfaces
Precleaning and disinfecting	May be less expensive than surface barriers	Requires more time and therefore may not be done properly Not all surfaces can be adequately precleaned. Over time, some chemicals are destructive to dental equipment surfaces. No method to determine whether the microbes have been removed or killed Some disinfectants must be prepared fresh daily. Chemicals are added to the environment upon disposal.
	Does not add plastic to the environment
	Some dentists do not like the appearance of plastic barriers.

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Surface Contamination

Two methods that may be used to deal with surface contamination are (1) to prevent the surface from becoming contaminated with the use of a surface barrier, and (2) to preclean and disinfect the surface between patients. Each has advantages and disadvantages, and most dental offices use a combination of surface disinfection and surface barriers.

Smooth, hard surfaces such as countertops, handles, supply containers, and bottles can be quickly and easily cleaned (Fig. 20-2). Surfaces with crevices, knobs, or other difficult-to-clean features, such as light handles, air-water syringe handles, and electrical switches (which can short-circuit), are better protected with surface barriers.

FIG. 20-2 Smooth surfaces are easily sprayed and wiped.

It is the responsibility of the dental assistant to make certain that equipment and treatment room surfaces are properly managed to prevent patient-to-patient disease transmission.

Surface Barriers

Placing barriers on surfaces and equipment can prevent contamination of clinical contact areas, but barriers are especially important for those areas that are difficult to clean.

All surface barriers currently on the market should be resistant to fluids. Fluid-resistant barriers prevent microorganisms in saliva, blood, and other liquids from soaking through the barrier material to contact the surface underneath (Fig. 20-3). Some plastic bags are specially designed to fit the shapes of dental chairs, air-water syringes, hoses, pens, and light handles (Fig. 20-4). Other types of barrier materials include clear plastic wrap, bags, tubing, plastic tape, and plastic-backed paper (Figs. 20-5 and 20-6). Sticky tape is frequently used as a plastic barrier to protect smooth surfaces, such as touch pads on equipment or electrical switches on chairs and x-ray equipment. Aluminum foil can also be used because it is easily formed around any shape. Procedure 20-1 reviews the steps to be followed in placing and removing barriers.