Preventing Cross-Contamination

What are some effective strategies to reduce the risk of cross-contamination in the dental operatory?

The dental operatory is a prime source of infection, so surfaces in this area must be properly disinfected to avoid cross contamination. Environmental surfaces—such as light handles, chair adjustment switches, and counter tops, or equipment such as radiography items, air water syringe handles, and bracket trays—can easily become contaminated with a patient’s blood or saliva during treatment due to frequent touching.¹ Research indicates that in dentistry cross contamination related to hands is frequent, but does not always result in disease transmission.² Transmission of common pathogens via direct contact in dentistry includes herpes simplex viruses and bacteria such as Escherichia coli and Staphylococcus aureus.² Although extremely rare, disease transmission has occurred in the dental setting.³ Proper handling of environmental surfaces ultimately protects both patients and oral health professionals from harmful pathogens.¹

Prudent infection control procedures include a required cleaning step prior to chemical disinfection of environmental surfaces. Cleaning with vigorous physical disruption removes visible debris, which may inhibit the disinfectant. This can be achieved by one of two methods: spray-wipe- spray or wipe-discard-wipe. A clean surface allows the disinfectant to work properly against microorganisms. An impervious plastic barrier should be used if surfaces or equipment cannot be easily cleaned.¹

Environmental surfaces fall into two categories: clinical contact surfaces and housekeeping surfaces. Clinical contact surfaces and equipment—such as handles, switches, computers, counter tops, and radiographic items—are at increased risk for contamination due to direct spray, splash, and spatter of blood and saliva generated during dental procedures, and because of frequent touching. On the other hand, housekeeping surfaces—such as floors, walls, and sinks—do not pose a risk for disease transmission so they only require routine cleaning—not disinfection—unless visibly soiled with blood.¹

Clinical contact surfaces and equipment require more rigorous disinfection with an Environmental Protection Agency (EPA)-registered hospital-grade intermediate-level disinfectant.1 The EPA-approved intermediate-level disinfectants for dentistry can be found on the EPA N list.⁴ Disinfectants must remain on surfaces for a prescribed amount of time to be effective and are divided into three category levels: low, intermediate, and high. Low-level disinfectants are considered hospital grade and are effective against hepatitis A (HAV), hepatitis B (HBV), and human immunodeficiency virus (HIV). Intermediate-level disinfectants have a label claim effectiveness for HAV, HBV, and HIV, in addition to a tuberculocidal claim. Mycobacterium tuberculosis is a hearty test organism whose eradication is frequently used to meet the intermediate-level label claim.¹

High-level disinfectants are liquid chemicals used for critical and semicritical instruments that cannot withstand steam sterilization, and are not used for surface disinfection due to their caustic nature. Housekeeping surfaces, on the other hand, only require routine cleaning to remove dirt and dust.¹

Cleaning and disinfection are common methods to protect clinical contact surfaces and equipment. However, impervious plastic barriers can also be used to avoid cross-contamination. Some surfaces or equipment, such as digital radiographic sensors, are difficult to clean and disinfect, so using barriers makes more sense. Barriers can be placed and discarded after each patient without the need for the time-consuming steps of spraying, wiping, and waiting for disinfectant contact time, unless the surface underneath was contaminated by blood or saliva. In that case, the surface must be cleaned and disinfected before barriers are replaced.¹ During operatory turnover, surfaces must be carefully examined prior to replacing barriers to avoid cross-contamination.

Another method for reducing cross-contamination is implementing single-use, disposable items such as prophy angles, saliva ejectors, adhesive bib holders, cotton rolls, burs, and air water syringe tips. Single- use, disposable items are used on one patient an then discarded, making operatory turnaround efficient and safe.

Metal or reusable air water syringe tips can be problematic with cross-contamination due to internal corrosion and small lumens that make visual inspection and cleaning difficult.^5,6 Although there have been no reports of disease transmission from metal air/ water syringe tips, studies have shown that debris and “black matter” remained after multiple cycles of ultrasonic cleaning and heat sterilization.⁶ Debris inhibits the sterilization process, reinforcing the need for cleaning prior to sterilization. It is nearly impossible to achieve cleaning prior to sterilization with metal air/ water syringe tips. Single-use disposable air/ water syringe tips are an excellent alternative. The United States Centers for Disease Control and Prevention encourages singleuse disposables for items that are difficult to clean; they are a better choice for safe patient care.¹

Critical thinking regarding the touching of surfaces is one last method to avoid cross-contamination. Using a “zone” system, such as a red zone for highly contaminated areas (bracket tray), a yellow zone for moderately contaminated areas (radiographic equipment), and a green zone for low contamination (counter top), can be helpful. Consider clinical contact surfaces or equipment when wearing contaminated gloves, remaining mindful of touching contaminated or uncontaminated surfaces while ungloved, using disposables, using a “zone” system, and unit dose dispensing of supplies as needed. All of these recommendations can reduce cross-contamination in the operatory.

References

1. Kohn WG, Collins AS, Cleveland JL, et al. Guidelines for infection control in dental healthcare settings–2003. MMWR Recomm Rep. 2003;52(RR-17):1–66.
2. Volgenant CM, de Soet JJ. Cross-transmission in the dental office: Does this make you ill? Curr Oral Health Rep. 2018;5:221–228.
3. Dental Healthcare-Associated Transmission of Hepatitis C: Final Report of Public Health Investigation and Response. Available at: ok.g/v/health2/documents/Dental%20Healthca_e_Final%20Report_2_17_15.pdf. Accessed March 15, 2022.
4. Environmental Protection Agency. About List N: Disinfectants for Coronavirus. Available at: epa.gov/coronavirus/about-list-n-disinfectants-coronavirus-covid-19-0. Accessed on March 15, 2022.
5. Inger M, Bennani V, Farella M, Bennani F, Cannon RD. Efficacy of air/ water syringe tip sterilization. Australian Dent J. 2014;59:87–92.
6. Puttaiah R, Cottone J, Guildersleeve J, Azmoudeh A, Tenney J. Rationale for using single-use disposable air/ water syringe tips. Compend Contin Educ Dent. 1999;20:1056–1069.

From Dimensions of Dental Hygiene. April 2022;20(4):10, 12.