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Nail Hygiene

Maintaining healthy fingernails is key to reducing microbial transmission in the dental setting.

Health care-associated infections remain a significant public health concern. Accord­ing to the United States Centers for Disease Control and Prevention (CDC), approximately one in 20 hospitalized patients develops an infection due to the provision of medical care.1 Following proper hand hygiene protocol is one strategy that is proven to reduce the incidence of health care-associated infections, and the maintenance of healthy fingernails is an integral part of this protocol.


Hands are the most common reservoir for transmittable microbes and bacteria. Microorganisms found on hands can be classified into two categories: resident flora and transient flora. Resident flora is naturally occurring on hands and is difficult to remove with handwashing.2 Examples of resident flora include Staphylococcus aureus, Proteus mirabilis, Klebsiella spp, and Acinetobacter spp.3 Though naturally occurring on the hands, resident flora-associated microbes are not generally implicated in disease transmission.2 Transient microorganisms, on the other hand, are not naturally occurring and can contaminate hands and the environment. These are implicated in disease transmission, and are easily removed through handwashing. Transient organisms commonly found on health care workers’ hands include: Enterococci, Clostridium difficile, S. aureus, Klebsiella spp,3 and hepatitis A and hepatitis C viruses.4 During patient care, dental hygienists may be exposed to the hepatitis B virus, human immunodeficiency virus, herpes simplex viruses, cytomegalovirus, and influenza. Additional microbial threats include severe acute respiratory syndrome, avian influenza strain H5N1, extensively drug-resistant tuberculosis, and methicillin-resistant S. aureus.5

In health care settings, compliance with hand hygiene is low (30%).6 Among dental professionals, however, hand hygiene compliance is much higher. In a 2008 survey conducted by Myers et al,7 only 6% of dentists reported that they did not perform effective hand hygiene procedures at the beginning of the practice day. In a 2013 survey by Garland,8 only 11% of dental hygienists noted they did not perform hand hygiene between patients.

Dental hygienists must adhere to evidence-based and accepted practices of infection control protocol. Proper hand hygiene practice is the single most important component of the infection control process for dental hygienists, and it reduces the transmission of microorganisms between clinicians and patients.7 Transmission of pathogens from the hands may occur via three pathways:

  1. Resident flora and transient organisms on the patient’s skin or inanimate objects surrounding the patient
  2. Transient organisms left on clinicians’ hands due to poor hand hygiene; organisms can then be transferred to inanimate objects or patients
  3. Cross-contamination of organisms by unwashed or incompletely cleaned hands3


Nail adornments present barriers to infection control and proper hand hygiene. The wearing of artificial nails, nail polish, and long, natural nails is problematic because they are more likely to harbor pathogens that quickly multiply in moist environments, such as the area underneath gloves.10 As gloves may have unseen defects or tear during treatment, patients may become exposed to these pathogens. This risk is especially high for immunocompromised patients.11


The CDC and World Health Organization (WHO) both discourage health care professionals from wearing artificial nails.12,13 The application of artificial nails—such as overlays, acrylics, wraps, gels, tips, silks, fiberglass, and bonding—can cause trauma to the natural nail, resulting in onychomycosis or bacterial infection.10 Infections related to nail applications have been linked to health care-associated infections and Gram-negative bacteria outbreaks of Pseudomonas­aeruginosa, Serratia marscescens, Klebsiella pneumonia, and Candida albicans.14

Several potential complications may arise when artificial nails are placed. When the soft tissue around the natural finger nail is manipulated during application, the soft periungual tissue under the nail bed may become irritated or traumatized, leading to infection.15 Onychomycosis is a fungal infection on the nail bed frequently spread through nail salons.16 Although many salons in the US adhere to strict protocols set by state cosmetology boards to prevent the spread of bacterial, fungal, and viral pathogens, others do not properly sanitize files, clippers, and other manicure-related instruments—increasing the risk of infection among their customers.15

Many health care institutions and associations strongly discourage the use of artificial nails by any clinician involved in direct patient care due to the following:14

  • They inhibit proper hand hygiene
  • Artificial nails can lift at the edges, creating a breeding ground for microorganisms
  • They harbor significantly more pathogens than natural nails
  • Moisture between the natural and false nail encourages multiplication of fungal organisms
  • They interfere with the donning of gloves and may promote glove tearing
  • The colonization of bacteria under artificial nails increases with time

Significantly more pathogenic microbes can be cultured from health care workers’ artificial nails compared to natural nails, both before and after performing proper hand hygiene practices. Neither soap-and-water handwashing nor alcohol-based hand sanitizers are able to adequately eliminate pathogenic microbes from artificial nails.17

Multiple research studies have linked artificial nails to health care-associated infections, including outbreaks of Gram-negative bacilli. In 2004, 46 infants were infected with Pseudomonas aeruginosa—16 of whom died—during an outbreak that was traced back to the artificial nails of two nurses.18


There isn’t research to demonstrate that more Gram-negative bacilli are likely to accumulate on polished fingernails when compared to natural nails. However, Fadernes and Lingaas17 did find that more bacteria were detectable on nails with chipped or old nail polish (worn longer than 4 days) than natural unpolished nails or nails with fresh unchipped nail polish. When nail polish chips, uneven surfaces are created that can harbor microorganisms.10

In 2012, the Cochrane Collaboration found that chipped nail polish was more likely to harbor bacteria and that nail polish may interfere with the efficacy of handwashing.9 Chipped nail polish should always be removed to prevent accumulation of pathogens on the nail surface, and polish should not remain on fingernails for more than 4 days.17


Most microbes on the hands are found on or under fingernails.10 Shorter nails are associated with less bacterial growth and are more properly cleansed during handwashing.2 Fingernails longer than 2 mm are more likely to harbor bacteria than shorter nails.17 Health care professionals with nails longer than 3 mm have a one in six chance of carrying Gram-negative P. aeruginosa, compared to a one in 80 chance among clinicians with short nails.10

Just as artificial nails may contribute to glove failure, natural nails that are too long may also cause gloves to tear when donning.10 The failure rate of gloves increases with fingernail length.16 Natural nails should always be short and clean.10 The CDC and WHO both recommend that nails be 0.5 mm or shorter.12,13


In order to prevent the transmission of infectious microorganisms, dental hygienists must adhere to recommended hand hygiene protocols. Fingernails should always be kept short and clean, and sharp edges should be repaired or filed as soon as possible. Clinicians should avoid artificial nails, long natural nails, and nail adornments. By remaining vigilant with hand hygiene, dental hygienists are able to protect their health and the health of the patients they serve.


  1. Centers for Disease Control and Prevention. Health Care-Associated Infections. Available at: Accessed February 18, 2014.
  2. Walton E. Hand hygiene for dental nurses. Dental Nursing. 2011;5:16–23.
  3. Shah S, Singhal T. Hand hygiene and health care-associated infections: What, why and how. Pediatric Infectious Disease. 2013;5(3):130–134.
  4. d versus gel and standard versus virucidal alcohol-based hand rub formulations among dental students. Am J Infect Control. 2013;41:1007–1011.
  5. Paola LG, Fried JI. Hand hygiene: the most effective way to prevent the spread of disease. Access. 2007;11:22–27.
  6. dos Santos RP, Konkewicz LR, Nagel FM, et al. Changes in hand hygiene compliance after a multimodal intervention and seasonality variation. Am J Infect Control. 2013;41:1012–1016.
  7. Myers R, Larson E, Cheng B, Schwartz A, Da Silva K, Kunzel C. Hand hygiene among general practice dentists: A survey of knowledge, attitudes, and practices. J Am Dent Assoc. 2008;139:948–957.
  8. Garland K. A survey of United States dental hygienists’ knowledge, attitudes, and practices with infection control guidelines. J Dent Hyg. 2013;87:140–151.
  9. World Health Organization. WHO Guidelines on Hand Hygiene in Health Care. Available at: Accessed February 18, 2014.
  10. Arrowsmith VA,Taylor R. Removal of nail polish and finger rings to prevent surgical infection. Cochrane Database Syst Rev. 2012;5:CD003325.
  11. Messano GA. Bacterial and fungal contamination of dental hygienists’ hands with and without finger rings. Acta Stomatologica Naissi. 2013;29(67):1260–1264.
  12. Saiman L, Lerner A, Saal L, et al. Banning artificial nails from health care settings. Am J Infect Control. 2002;30:252–254.
  13. Ward DJ. Hand adornment and infection control. Br J Nurs. 2007;16:654–656.
  14. Rich P. Nail cosmetics. Dermatol Clin. 2006;24:393–399.
  15. Sullivan EE. Off with her nails. J Perianesth Nurs. 2003;18:417–418.
  16. Fagernes M, Lingaas E. Factors interfering with the microflora on hands: a regression analysis of samples from 465 healthcare workers. J Adv Nurs. 2011;67:297–307.
  17. Moolenaar RL, Crutcher JM, San Joaquin VH, et al. A prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: did staff fingernails play a role in disease transmission? Infect Control Hosp Epidemiol. 2000;21:80–85.
  18. Boyce JM, Pittet D, Healthcare Infection Control Practices Advisory Committee; HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. Guideline for Hand Hygiene in Health-Care Settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. Society for Healthcare Epidemiology of America/Association for Professionals in Infection Control/Infectious Diseases Society of America. MMWR Recomm Rep. 2002;51:1–45.

From Dimensions of Dental Hygiene. March 2014;12(3):28,30,32.


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