Inside Dental Assisting
Disinfection of Clinical Surfaces
Managing the surfaces of the dental operatory is critical to keeping patients and staff safe from infection.
Eve Cuny, MS
Dental operatory surfaces and equipment can become contaminated with patients’ blood and other oral fluids through contact with dental healthcare personnel’s (DHCP) gloved hands; spray and splash created by dental instruments such as handpieces, air/water syringes, and ultrasonic scalers; and through contact with contaminated instruments placed on various surfaces. Determining the management of environmental surfaces in the dental setting requires attention to the areas and objects that may become contaminated during patient treatment and classification of disinfectants and surfaces to guide DHCP in proper technique and materials for disinfection.
Classification of Disinfectants
E.H. Spaulding, a pioneer in healthcare disinfection and sterilization, identified three classifications of disinfectants, based on the product’s ability to kill certain organisms.1 High-level disinfectants are capable of killing all microorganisms, including resistant bacterial spores. High-level disinfectants, such as glutaraldehyde and hydrogen peroxide-based products, are not appropriate for use on environmental surfaces and dental equipment; these products are intended for immersion disinfection or sterilization of heat-sensitive instruments.2
Intermediate-level disinfectants are not necessarily capable of killing spores, but will inactivate Mycobacterium tuberculosis var. bovis, which is considerably more difficult to kill than vegetative bacteria. These intermediate-level disinfectants will also kill fungi and all types of viruses.2
Low-level disinfectants will not reliably inactivate spores, mycobacteria, all fungi, and all viruses.2 Some disinfectants have active ingredients that at one concentration will be categorized as intermediate-level and at a different concentration will be classified as low-level. Careful review of the manufacturer’s label of a product will provide the necessary information to select among the three classifications of disinfectants and the proper dilution and use of the product.
Classification of Environmental Surfaces
Environmental surfaces carry a lower risk of disease transmission than do instruments and devices that come into direct contact with patients.2 Surfaces in the dental operatory can be divided into two broad categories for purposes of determining the level of decontamination indicated: medical equipment surfaces and housekeeping surfaces.3 Oral healthcare settings differ from most other healthcare settings in that DHCP often use aerosol and spray-producing equipment such as handpieces, ultrasonic scalers, air/water syringes, and other devices. The spray from these devices can contain blood that then settles on the surfaces and equipment in the area around the patient’s head.4,5 The medical equipment surfaces, which are also called clinical contact surfaces,6 must be decontaminated between patients to avoid inadvertent cross-contamination. Some examples of surfaces that may be considered clinical contact surfaces include dental radiographic equipment, knobs, switches, light handles, drawer handles, chairside computers, countertops, nitrous oxide equipment, and digital impression devices, among others. For all of the clinical contact surfaces, barriers that are impervious to fluids are an acceptable alternative to disinfection (Figure 1). When using barriers, change them between each patient and carefully place and remove them in a manner that does not cause contamination of the protected surface or the DHCP’s hands. Used barriers should only be handled while wearing gloves.6
Housekeeping surfaces have the least potential for cross-contamination, and therefore require less stringent procedures than clinical contact surfaces.2 Examples of housekeeping surfaces include floors, walls, sinks, windowsills, and other areas within the dental operatory that are not directly contacted by DHCP and patients during patient treatment. Housekeeping surfaces should be cleaned on a regular basis using soap and water.2 Studies in hospital settings showed no difference in healthcare-associated infection rates when disinfectants were used instead of soap and water to clean floors. If there is uncertainty regarding the nature of contamination—or there is overt blood present on the surface—an EPA-registered hospital disinfectant should be used when cleaning floors.7,8 Because studies regarding housekeeping surfaces are relatively small and lack strong statistical significance, some recommendations conclude that either detergent and water or a disinfectant is indicated for floors in healthcare settings.3 The judgment in this area should be based on the level of contamination and the likelihood of transferring contamination from the floor surface to the patient. Unless contamination is suspected, vertical surfaces such as walls do not require routine cleaning and disinfecting.6
Two agencies within the US government regulate the manufacture of disinfectants used in healthcare settings. The Environmental Protection Agency (EPA) regulates disinfectants for use on environmental surfaces. The Food and Drug Administration (FDA) regulates the manufacture of liquid chemical sterilants and high-level disinfectants. Liquid chemical sterilants/high-level disinfectants are not appropriate for use on environmental surfaces and should be used for immersion of heat-sensitive items only. Products registered with the EPA are classified as hospital-level disinfectants and carry the EPA registration number on the label (Figure 2). All claims for germicidal activity must be reviewed by the EPA and supported through testing by the manufacturer. The EPA does not recognize the distinction between low- and intermediate-level disinfectants in its registration procedures, so this will not be reflected on the EPA registration label. The way to determine if a product is intermediate-level is by whether it has a claim as a tuberculocidal disinfectant on the product label. Disinfectants that are EPA-registered as a hospital-level disinfectant, but do not kill tubercle bacillus, are categorized as low-level disinfectants.
The Occupational Safety and Health Administration (OSHA) also regulates the use of disinfectants as they relate to healthcare in the Bloodborne Pathogens Rule. OSHA requires that contaminated work surfaces be decontaminated at the end of procedures, after blood spills, as soon as feasible after becoming overtly contaminated, and then at the end of the work shift if contamination has occurred since the last decontamination.9 OSHA does not specify the type or level of disinfection, but it does indicate that impervious barriers are an acceptable alternative to chemical disinfection.
Simply applying a disinfectant to a clinical contact surface will not reliably decontaminate the surface. A number of factors influence the effectiveness of the disinfectant and the disinfecting process. The number and location of the microorganisms is significant, because there is a relationship between the total number of organisms and the time needed for complete destruction. Cleaning surfaces before applying disinfectant solution will reduce the total microbial contamination, reducing the amount of time needed for germicides to work (Figure 3). In addition, clumped cells are more difficult to inactivate, and the physical activity of cleaning a surface helps disrupt potential clusters or clumps of debris containing microbes.3
Other factors that can influence the effectiveness of disinfectants include dilution, temperature, pH, relative humidity, and water hardness. Organic debris, such as blood, tissue, or lubricant material, can interfere with the efficacy of disinfectants either by chemical reaction between the material and the germicide or by the organic material’s acting as a physical barrier that protects microorganisms.10
The time needed for disinfectants to kill the organisms listed on the label is provided by the manufacturer, and DHCP performing disinfection procedures should ensure that the surfaces remain wet for the time indicated to ensure complete disinfection. Do not include the time needed to preclean the surface in the disinfection time. Therefore, the CDC recommends the use of products with short contact times (1 to 3 minutes) rather than disinfectants that require longer contact times (10 minutes).3
Disinfectants may be delivered as either a spray or a wipe to clinical contact surfaces. In either case, the procedure is the same. The surfaces should be sprayed, then wiped, or they should be wiped with disinfectant-soaked towelettes, to remove debris. After the cleaning step, the surface should be sprayed again, or wiped with disinfectant towelettes and allowed to remain wet for the time indicated on the product label. A fresh wipe should be used for each of the cleaning and disinfecting steps. There is some indication that the improper use of wipes (ie, the use of one wipe on multiple surfaces) may result in the cross-contamination of surfaces in the patient environment.11
The management of clinical contact surfaces remains an important aspect of an infection control program for all oral healthcare settings. Understanding the proper use and selection of disinfectants and barriers helps ensure a safe patient environment. Disinfectant products are sensitive to a number of factors that can affect their potency; therefore, DHCP using these products should receive appropriate training and should always reference the manufacturer’s directions for use, dilution, and shelf life.
1. Spaulding EH. Chemical disinfection and antisepsis in the hospital. J Hosp Res. 1972;9:5-31.
2. Favero MS, Bond WW. Chemical disinfection of medical and surgical material [Chapter 43]. In: Block SS, ed. Disinfection, Sterilization and Preservation. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2001:881-917.
3. Rutala WA, Weber DJ. Healthcare Infection Control Practices Advisory Committee. Guideline for disinfection and sterilization in healthcare facilities, 2008. Available at: www.cdc.gov/hicpac/Disinfection_Sterilization/toc.html. Accessed June 1, 2011.
4. Cristina ML, Spagnolo AM, Sartini M, et al. Evaluation of the risk of infection through exposure to aerosols and spatters in dentistry. Am J Infect Control. 2008;36:304-307.
5. Harrel SK, Barnes JB, Rivera-Hidalgo F. Aerosol and splatter contamination from the operative site during ultrasonic scaling. J Am Dent Assoc. 1998;129:1241-1249.
6. Centers for Disease Control and Prevention. Guidelines for Infection Control in Dental Health-Care Settings – 2003. MMWR. 2003;52(RR-17)1-66.
7. Dharan S, Mourouga P, Copin P, et al. Routine disinfection of patients’ environmental surfaces. Myth or reality? J Hosp Infect. 1999;42:113-117.
8. Danforth D, Nicolle LE, Hume K, et al. Nosocomial infections on nursing units with floors cleaned with a disinfectant compared with detergent. J Hosp Infect. 1987;19:515-518.
9. US Department of Labor, Occupational Safety and Health Administration. 29 CFR Part 1910.1030. Occupational exposure to bloodborne pathogens, needlesticks and other sharps injuries; final rule. Federal Register 2001;66:5317-25. [As amended from and includes 29 CFR Part 1910:1030. Federal Register 1991;56:64174-82.]
10. Lewis DL, Arens M. Resistance of microorganisms to disinfection in dental and medical devices. Nat Med. 1995;1:956-958.
11. Williams GT, Denyer SP, Hosein IK, et al. Limitations of the efficacy of surface disinfection in the healthcare setting. Infect Control Hosp Epidemiol. 2009;30(6):570-573.
About the Author
Eve Cuny, MS
Assistant Professor, Dental Practice
Director, Environmental Health and Safety
University of the Pacific
Arthur A. Dugoni School of Dentistry
San Francisco, California