Environmental Surface Asepsis

Dental practitioners may be exposed to a variety of pathogenic microorganisms when providing dental treatment. Exposure can occur via direct contact with saliva and blood or indirectly through contact with contaminated instruments, equipment, and environmental work surfaces.1-3

This article reviews environmental surface asepsis, including the materials and methods used for surface disinfection.

 

ENVIRONMENTAL SURFACES

There are 2 types of dental environmental surfaces: clinical contact surfaces and housekeeping surfaces. Clinical contact surfaces are touched frequently with gloved hands during patient care, or may become contaminated with blood, saliva, or other potentially infectious material and then come in contact with instruments, devices, hands, or gloves. Housekeeping surfaces (eg, floors, walls, and sinks) do not come in contact with hands or devices used in dental procedures. Proper treatment of clinical contact surfaces is required before they become involved in the care of the next patient. Treatment of housekeeping surfaces can occur at the end of the day.1-3

Table 1. Surface Covers Versus Precleaning Followed by Disinfection.*
Surface Covers
Positives
Limitations
• Prevents contamination of covered surfaces • Numerous different sizes and types
may be required
• Protects surfaces that are difficult or should not be precleaned and disinfected • Could make the operatory aesthetically unattractive
to patients and practitioners
• Can be less labor intensive to apply
• May be more expensive than precleaning and disinfecting agents
• Reduces handling and storing of disinfectant and practitioner exposure to chemical agents • Adds to office waste stream
Precleaning and Disinfection  

Positives
Limitations
• Fewer items required/purchased • Increases practitioner exposure to
chemicals
• May be less expensive than surface covers • Can be more labor/time intensive to complete
• Usually does not make the operatory aesthetically unattractive to patients and practitioners • Personal protective equipment required during application
• Adds less to the office waste stream • Some surfaces cannot be properly or safely precleaned and/or disinfected
• Processes are familiar to practitioners • Requires proper handling and
storage as well as labeling and
material safety data sheets
  • Some chemicals must be
prepared daily
  • Chemical disposal can stress the
environment
*Modified From References 1 to 3.  

There are 2 general approaches to environmental surface asepsis (Table 1). One way to prevent contamination is with the use of surface covers. The other approach is to preclean and disinfect surfaces after contamination and before reuse. Each approach has advantages and disadvantages. Dental practices usually employ a combination of both.1-3

Surface covers take little time to place, cover surfaces difficult or impossible to disinfect, and reduce the exposure of workers to chemicals. Covers can be demanding, as a variety of sizes and shapes may be required, and may be aesthetically unattractive.1-3

Disinfection may be less expensive than covering, involves processes familiar to practitioners, and produces less waste material. Disinfection increases practitioner exposure to chemicals and requires that personal protective equipment (PPE) such as masks and protective eyewear be worn. Some chemicals need to be mixed in a specific manner and prepared daily. All chemicals have to be stored correctly with proper labeling, and material safety data sheets should be easily accessible for reference.1-4

MICROORGANISMS

Because Mycobacterium tuberculosis is more difficult to kill than most other microorganisms, disinfectants with tuberculocidal activity are acceptable for use in most situations in dentistry. Tuberculocidal agents are usually effective against nonenveloped (hydrophilic, such as poliovirus) and enveloped (lipophilic, such as herpes virus, influenza, and HIV) viruses.1-4

Different microorganisms survive on environmental surfaces for widely varying amounts of time. Factors influencing survival include temperature, humidity, inoculating dose, and the presence of blood and saliva. Thus, predicting the number and types of microorganisms present on a contaminated surface is impossible. The safest approach is to assume that any contamination contains viable microorganisms. Removal and/or killing of microorganisms before treatment of the next patient are thus required.

PRECLEANING

Precleaning and disinfection best occur on smooth, easily accessible, nonporous surfaces. These types of surfaces best afford good contact with decontaminating chemicals. Proper precleaning (predisinfection) is essential to reduce the bioburden present initially, so that disinfection will have a better chance to kill a reduced number of residual microorganisms.

The practitioner should always check the surface-cleaning ability of an agent. Water-based agents solubilize organic materials such as blood and saliva. Precleaning agents are often the same chemical used for disinfection.

Not all contaminated surfaces in dental practices can be precleaned and/or disinfected well or easily. Buttons, control switches, and drawer pulls are examples of difficult-to-clean items and are best covered with a barrier.

The practitioner should always wear PPE when disinfecting surfaces and equipment. This includes utility gloves (not clinical-use gloves), masks, protective eyewear, and protective clothing. Proper use will minimize worker contact with both contaminants and chemicals.

SURFACE DISINFECTION

After properly precleaning, surfaces are ready for disinfection. The most frequently used method of disinfection is the spray-wipe-spray technique, but wiping surfaces with disinfectant wipes or towelettes is equally effective. Spray-wipe is the precleaning step, while the second spray is disinfection. Complete coverage of surfaces is required. Sur-faces need to remain moist for the longest contact time (usually 5 to 10 minutes) indicated by the manufacturer. Removal of residual moisture is accomplished with a paper towel. Alternatively, premoistened disinfectant wipes can be used.

Intermediate-level disinfection is required to treat clinical contact surfaces in dentistry. Such agents can destroy vegetative bacteria, which include most fungi and viruses. They can also inactivate Mycobacterium bovis (tuberculocidal) in 10 minutes of exposure or less. Disinfectant containers must have an EPA registration number. Examples of these agents include chlorine-based products, phenolics, iodophors, quaternary ammonium compounds with alcohol, and bromides.

Antimicrobial chemicals come in 4 general types: (1) antibiotics (for killing microorganisms in or on the body); (2) antiseptics (for killing microorganisms on the skin or other body surfaces); (3) disinfectants (for killing microorganisms on environmental/inanimate surfaces or objects), and (4) sterilants (for killing all microorganisms on inanimate objects).1

Table 2. Categories of Surface-Disinfecting Chemicals.*
Chemical Category
Definition
Examples
Uses
(1) High-level disinfection Can destroy all microorganisms, save high numbers of bacterial endospores Glutaraldehyde, hydrogenperoxide, glutaraldehydephenate, hydrogen peroxide with peracetic acid, peracetic acid and orthophthalaldehyde Heat-sensitive items; immersion only

Not appropriate for environ-mental surface disinfection
(2) Intermediate-level disinfection Can destroy vegetative bacteria, most fungi and viruses

EPA-registered hospital disinfectants with label claims of tuberculocidal activity**


Chlorine-based products, phenolics, iodophors, quaternary
ammonium compounds with alcohol, and bromides

Clinical contact surfaces and noncritical surfaces soiled with visible blood
(3) Low-level disinfection

Can destory vegetable bacteria, some fungi and viruses

 

Cannot inactivate Mycobacterium bovis (not tuber-culocidal)

EPA-registered hospital disinfectants that lack label claims of tuberculocidal acitvity **

 

Quaternary ammonium compunds

Housekeeping surfaces such as floors, walls, and noncritical surfaces without visable blood

Clinical contact surfaces#


*Modified From References 1 to 3.

**Hospital disinfectants have been shown to kill Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella choleraesuis; EPA = Environmental Protection Agency.

#The Centers for Disease Control and Prevention indicate that low-level disinfectants can be used on clinical contact surfaces in addition to an EPA-registered hospital disinfectant if the low-level disinfectant has a label claim of being able to kill human immunodeficiency virus and hepatitis B virus.

The Centers for Disease Control and Prevention have categorized disinfectants based on their microbial spectrum of activity (Table 2). The categories include the following: sterilant/high-level disinfectant (for killing all microorganisms on submerged inanimate objects that are heat sensitive); intermediate-level disinfectant (for killing vegetative bacteria, most fungi, and M. tuberculosis); and low-level disinfectant (for killing most vegetative bacteria, some fungi, and some viruses).1,2

SUMMARY

Environmental surface disinfection is easily accomplished with precleaning and disinfection techniques, and prepared surfaces or difficult-to-clean items can be covered with impermeable barriers. When carried out effectively, both practitioners and patients are protected from exposure to microorganisms that transmit disease and cause illness.


References

1. Miller CH, Palenik CJ. Infection Control & Management of Hazardous Materials for the Dental Team. 3rd ed. St Louis, Mo: Mosby-Year Book; 2004:260-275.

2. Kohn WG, Collins AS, Cleveland JL, et al. Centers for Disease Control and Prevention. Guidelines for infection control in dental health-care settings – 2003. MMWR Recomm Rep. 2003;52(RR-17):1-61.

3. Organization for Safety & Asepsis Procedures. From Policy to Practice: OSAP’s Guide to the Guidelines. Annapolis, Md: OSAP; 2004:45-62.

4. Organization for Safety & Asepsis Procedures. Surface disinfectants for dentistry: tools for selecting and using surface disinfectants in dental settings. Infection Control In Practice. May 2005; Vol 4:1-4.




Dr. Palenik has held over the last 25 years a number of academic and administrative positions at Indiana University School of Dentistry. These include professor of oral microbiology, director of human health and safety, director of central sterilization services, and chairman of infection control and hazardous materials management committees. Currently he is director of infection control research and services. Dr. Palenik has published 175 articles, more than 305 monographs, 3 books, and 7 book chapters, the majority of which involve infection control and human safety and health. Also, he has provided more than 100 continuing education courses throughout the United States and 8 foreign countries. All questions should be directed to OSAP at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
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