Gillian M. McCarthy, BDS, M.Sc.
© J Can Dent Assoc 2000; 66:556-7
Universal precautions (UPs) were introduced to minimize transmission of bloodborne pathogens to health care workers in 1987. They involve a single standard that should be applied to all patients at all times. UPs are particularly relevant for dental procedures that may involve blood and/or blood-contaminated saliva, and are integral components of current infection control recommendations for dentistry.1-4 In 1996, the Centers for Disease Control updated infection control protocols to include standard precautions a combination of UPs for prevention of transmission of bloodborne pathogens and body substance isolation precautions. Standard precautions expanded the principles of UPs to all body fluids to minimize the risk of cross-infection among both patients and health care workers.
Necessity for Standard and Universal Precautions
These precautions are necessary because some patients do not disclose their infectious status, and many are unaware that they are infected (there may be no signs or symptoms as a result of incubation periods or subclinical disease). In addition, antibodies or other markers of infection may be undetectable during the window period immediately after infection. This is particularly relevant in HIV infections because the levels of circulating virus (viral load) and the maximum infectivity for HIV are highest during the window period and with disease progression in AIDS patients.
Compliance with Recommended Infection Control Practices in the Dental Office
There is evidence that compliance with UPs among all health care workers is poor.5,6 Dentists generally compare favourably with other health care workers, and dentists compliance in Canada appears to be higher than in most other countries, although there is a clear need for improvement in some areas to reduce the risk of transmission of infection.7 In the 1995 national survey, a high proportion of Canadian dentists reported immunization against hepatitis B virus (HBV) (91%), routine use of gloves (95%), or masks (82%) and protective eye wear (82%) when splatter is expected. Routine handwashing before treating each patient and after removing gloves was reported by 76% and 63% of dentists respectively. However, compliance with hand hygiene practices is likely to improve with the recent introduction of hand disinfection as an effective alternative to handwashing as it can save time and reduce dermatitis (John, this issue, p. 546). Approximately three quarters of dentists reported HBV immunization of all clinical staff, biologic monitoring to verify the efficacy of heat sterilizers and sterilization of handpieces after each patient visit a practice based on evidence that the potential for transmission of pathogens exists if handpieces are inadequately sterilized.8,9
Lower rates of compliance have been reported for flushing waterlines after use on each patient (55%) and postexposure protocols for needlestick injuries and cuts (41%).7 However, since these data were collected, guidelines for HIV postexposure prophylaxis (Gregson, this issue) and reducing contamination of waterlines have been updated (Barbeau, this issue) and compliance may have increased.
Evidence that Compliance with Universal Precautions Reduces Exposure
Compliance with UPs reduces exposure to blood and blood-contaminated saliva. In the Canadian national survey, dentists who used puncture-proof containers for disposal of sharps or those who routinely wore gloves reported significantly fewer percutaneous injuries.10 This confirms previous evidence of a decrease in percutaneous injuries with increasing compliance with UPs.11 Interestingly, dentists who reported percutaneous injuries in the last year and were thus more vulnerable to transmission of bloodborne pathogens were less likely to have a postexposure protocol.10 Dentists who consistently used masks or eye protection against splatters reported significantly fewer splashes of blood or blood-contaminated saliva to the eyes, nose or mouth. This provides evidence of the efficacy of masks and eye protection in reducing, but not eliminating, the risk of exposure. This indicates that improved compliance may reduce the risk of exposure; however, improvements in the efficacy of masks and eye protection are also necessary.
Dr. McCarthy is professor, School of Dentistry and the department of epidemiology and biostatistics, faculty of medicine and dentistry, The University of Western Ontario.
Correspondence to: Dr. Gillian McCarthy, School of Dentistry, Dental Sciences Building, The University of Western Ontario, London, ON N6A 5C1. E-mail: firstname.lastname@example.org
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