Louis G. DePaola, DDS, MS
Assistant Dean of Clinical Affairs
Professer, Department of Oncology and Diagnostic Sciences, Dental School, University of Maryland Baltimore

Why Is Surface Disinfection Necessary?
Anything that goes into a patient’s mouth is contaminated with that patient’s microflora. Additionally, any dental provider who touches an instrument, device or material that was in a patient’s mouth is also contaminated with that patient’s microflora. Furthermore, any surface that comes in contact with an instrument, device or material that was in a patient’s mouth is also contaminated. Thus surfaces in the dental operatory come into direct contact with a multitude of contaminated items on a routine basis. Therefore, if proper infection control practices are not followed, any of these contaminated items/surfaces can become a potential source of infection to subsequent patients and/or the dental staff.1 Additionally, the principles of infection control dictate the reduction of any source of contamination, including environmental surfaces and the most recent dental specific CDC Guidelines published in 2003 should serve as the standard for clinicians regarding the management and disinfection of environmental surfaces. That document can be downloaded in its entirety at
https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5217a1.htm.1

As a supplement to the 2003 document, in March of 2016, the CDC published the Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care which is the summary guide of basic infection prevention recommendations for all dental health care settings.2 Additionally, at the same time, the CDC published the Infection Prevention Checklist for Dental Settings: Basic Expectations for Safe Care which is a companion to the Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care. 2,3 This checklist is an excellent tool that each dental office can use to measure their compliance with the principles of infection control. The checklist can be downloaded from: https://www.cdc.gov/oralhealth/infectioncontrol/guidelines/

Defining the Surfaces in the Dental Operatory: Clinical Contact vs. Housekeeping
There are two types of surfaces in the dental operatory/office. Some surfaces are exposed to clinical contamination. Others surfaces are not in any patient contact areas. To help simplify which surfaces are which; the CDC has divided environmental surfaces in the dental office into two categories based on the degree and type of contamination to which the surface is exposed.1,2,3 Clinical contact surfaces are defined as any surface that has been either directly or indirectly contacted and/or touched by contaminated hands, aerosol, instruments, devices, or other items in the course of providing dental care.1,2,3 Examples of clinical contact surfaces include light handles; switches; dental radiology equipment inclusive of digital sensors; dental chairside computers including the mouse and keyboards; any reusable containers of dental materials; all drawer handles, doorknobs and faucet handles; countertops, mobile carts/cabinets; pens, pencils and telephones, intercom, ipads, cell phones and mobile devices.1,2,3 Any clinical contact surface should be:
1. Covered with impervious barrier which is changed between patients or
2. Surfaces not barrier protected should be cleaned and disinfected with an EPA-registered hospital disinfectant between patients

Disinfect the Surface or Cover With Barrier?
What is correct?
While disinfection and application of barriers are both effective; some surfaces are easier to cover; while disinfection may be the best methodology with other, especially larger, surfaces. As stated above, the clinician has the choice to either cover an environmental surface with an impervious barrier or disinfect that surface with an EPA-registered surface disinfectant. While either is acceptable, the use of barrier protection or chemical disinfection is largely a matter of practicality and personal choice Barrier protection is the most efficient way to protect difficult-to-clean, electronic and smaller surfaces. A variety of barrier materials are available, such as clear plastic wrap, bags, sheets, tubing, and plastic-backed paper. Any barrier material used on clinical contact surfaces must be impervious to fluid. Once properly affixed to the clinical contact surface, barriers are very effective in preventing both direct and indirect contamination.1 Any barrier is considered a single use device and must be discarded after every patient contact and replaced with a new barrier. At the end of each day, every clinical contact surface, regardless if barriers are used, should be cleaned and then disinfected with an EPA-registered disinfectant.1,2,3

EPA Registration
Any disinfectant used in the dental office must be registered by the Environmental Protection Agency (EPA). Interestingly, non-registered products may be sold, but the clinician who might use such a product violates a federal law and may be prosecuted. In the USA, all liquid chemical disinfectants used on noncritical surfaces as well as gaseous sterilants are regulated by the EPA in interstate commerce by the Antimicrobials Division, Office of Pesticide Programs, EPA, under the authority of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) of 1947, as amended in 1996.4 Enforcing FIFRA, the EPA requires registration of any substance or mixture of substances intended to prevent, destroy, repel, or mitigate any pest, including microorganisms. Therefore, an essential criterion for selecting a surface disinfectant is EPA registration. Additionally, infection control recommendations published in 2003 and the supporting documents in released 2016, the CDC recommends the use of an EPA-registered disinfectant for use on clinical contact surfaces in the dental office.1,2,3 Therefore, the use of unregistered products is not recommended and because it violates FIFRA, thus possibly subjecting the user to fines and/or sanctions.

Tuberculocidal Activity: What Does This Mean?
The term tuberculocidal is often used. Is it significant? If so, what does it mean to a dental practitioner? Tuberculosis is a very difficult organism to kill; only bacterial spores are more difficult to inactivate than Mycobacterium tuberoculosis.1,2,3 Therefore, activity of a disinfectant against TB (intermediate-level) is a good indicator of broad spectrum germicidal activity.1,2,3,6 The CDC and the FDA use the Spaulding Classification to classify disinfectants as high-level, intermediate or low-level disinfectants.1,2,3 According to Spaulding’s definition, an intermediate level disinfectant is tuberculocidal and the two terms are often used interchangeably.1,6 The EPA which regulates disinfectants; and in contrast to the CDC and FDA, registers environmental surface disinfectants based on the manufacturer’s microbiological activity claims when registering its disinfectant.4,5 The EPA does not use the terms intermediate; low-level disinfectants as used in CDC guidelines.1,2,3 In order for a product to be labeled as an EPA hospital disinfectant (low-level), it must pass Association of Official Analytical Chemists (AOAC) effectiveness tests against three target organisms:
1. Salmonella choleraesuis for effectiveness against gram-negative bacteria;
2. Staphylococcus aureus for effectiveness against gram-positive bacteria;
3. And Pseudomonas aeruginosa for effectiveness against a primarily nosocomial pathogen.1

Clean That Surface: Disinfection is inhibited or incomplete in the presence of bioburden and all the clinical contact surface(s) must be thoroughly cleaned before disinfection can occur. Therefore, the first fundamental step in the disinfection process is cleaning. Each clinical contact surfaces should be pre-cleaned; cleaned with an absorbent material containing a cleaning agent, usually a detergent, before application of the disinfectant.1 If thorough cleaning is not possible or practical, that surface should be covered with an impervious barrier.1 There are many formulations of disinfectants and a product that contains a detergent has the obvious advantage of providing the clinician with a cleaner/disinfectant in one formulation. This reduces the number of items in the office inventory, is more convenient, and usually decreases cost.

What About Wipe Formulations?
Many products are now available in a wipe formulation. This offers a convenient option for use of disinfectants and has a number of advantages. First, the wipe significantly limits the indiscriminate application of any chemical agent. The chemical is only applied to the area that the wipe contacts. This decreases human contact reducing possible allergic reactions. Wipes are also easy to use and store. On the negative side, all staff must be educated to immediately close the lid on the wipe container. Leaving the next wipe in the air encourages drying that will reduce the antimicrobial activity. Wipes cannot be used for some processes such as disinfection of impressions and some other dental laboratory disinfection. Wipes may not be effective cleaning large spills that contain contaminated material. A spray formulation should be utilized for these applications. Regardless of the type of disinfectant used, appropriate barriers must be utilized to protect the dental providers from contact with any chemical agent.

Conclusions
• All dental providers should comply with the Guidelines for Infection Control in Dental Health-Care Settings, 2003.1
• A self-assessment of each dental office’s compliance with CDC infection control recommendations should be performed using the Infection Prevention Checklist for Dental Settings: Basic Expectations for Safe Care.3
• Any deficiencies identified in the self-assessment should be remediated.
• All clinical contact surfaces should be managed according to CDC recommendations.
• Clinical contact surfaces should be either covered with an impervious barrier or disinfected with an EPA-registered liquid chemical germicide between each and every patient contact. All barriers must be changed between patients.
• Products that are tuberculocidal have a broader antimicrobial spectrum; non-enveloped viruses are killed.
• A shorted TB kill time can help lessen chair turnover time.
• Wipe formulations offer a safe and convenient way to apply disinfectants in the dental office.