Good News: Dentists Not at Risk of Acquiring HIV/AIDS from Infected Patients and the Illusion of Infection Control

by John Hardie, BDS, MSc, PhD, FRCDC

Since the appearance of HIV/AIDS in the mid-1980s, clinical dentists, academics and the profession’s regulatory agencies have been concerned about the possibility of an HIV/AIDS positive patient transmitting the infection to the attending dentist. A recent report in the American Journal of Infection Control categorically refutes this possibility. Prior to discussing these new findings, it is appropriate to provide pertinent historical details.

Historical Details
In his 1995 publication the author used the Centers for Disease Control’s (CDC) facts to argue that HIV transmission during dental treatment was an unlikely event.1 For example, by the mid-1980s the CDC knew that among 1,309 dental health care workers (1,132 dentists, 131 hygienists, 46 assistants) without self- reported behavioural risks for AIDS only one dentist (0.1%) had antibodies to HIV.2 {Regarding the one positive dentist, a 1988 CDC Update notes that there is a “tendency of health – care workers not to report behavioral risk factors for HIV infection.”3} Additional investigations in 1986 and 1987 demonstrated a complete absence of HIV antibodies among 529 dental workers.4,5,6 Readers should know that this was the state of affairs before the introduction of Universal and Standard Precautions. It is a fact that all of these dental personnel seldom if ever used gloves or masks, had frequent occupational exposures to persons with, or at risk for, HIV infection, and had often sustained accidental parenteral inoculations from sharp instruments. By mid-1987 the CDC knew that exposure to mucous membranes of HIV positive patients did not result in transmission to treating health professionals.7 In the same report the CDC admitted that the transmission of HIV did not occur from contaminated floors, walls, countertops and hospital waste.7 Based on these facts, there was absolutely no clinical evidence to suggest that dentists were at risk of contracting HIV/AIDS from infected patients. Nevertheless, in 1987 the CDC promulgated a series of infection control recommendations for dentistry with no proof that they were either necessary or effective.

In 2001 Neiburger published a “Letter to the Profession” in which he expanded on the non-necessity of these recommendations.8 His paper offers a comprehensive critique of the questionable practices used by government agencies to enact policies for which there is little- if any- justification. He rightly asks why subject all patients to mandated and not inexpensive procedures when, prior to their enactment, there was not a single case of a dentist occupationally acquiring HIV/AIDS.8

Although Neiburger emphasizes that the occupational transfer of HIV/AIDS has not been recorded during or after the introduction of Universal Precautions, the idea that dental personal are at risk has continued.8 For example, in 2006, McCarthy suggested that based on her epidemiologic research of dentists, dental hygienists, surgeons and nurses, there was a “large underestimate of occupationally acquired HIV infection.”9 There are three reasons for questioning this conclusion. One, the Public Health Agency of Canada found no cases of HIV in health workers exposed to the virus between 2000 and 2004.9 Two, the Canadian HIV/AIDS Surveillance Reports from 2006 onwards indicate a declining number of HIV cases and no suggestion that being a health care worker is an at risk category for acquiring HIV.10 Three, the findings of the article referred to in the Preamble.

New Findings
The recent report in the American Journal of Infection Control is based on a thirteen year study (2002-2015) of health care workers (HCWs) in a major US based academic medical centre exposed to HIV contaminated body fluids.11 The principal reason for conducting the investigation was the realization that the previously established rates of transmissions to health care workers were based on outdated data and lax protocols. For years it has been accepted that the risk of HIV transmission to HCWs was 0.3% following a percutaneous injury and 0.09% after a mucous membrane exposure.11 If these figures are no longer valid, the justification for Universal and Standard Precautions must be questioned.

The findings of this study are highly significant. During the 13-year period, 266 HCWs at the centre were exposed to the body fluids of HIV positive patients. Percutaneous injuries accounted for 52% of the exposures and 43% of the exposures were from mucocutaneous contacts. A small portion (4%) of the exposures were of uncertain etiology. Most of the injuries (52%) were to the hands with the face and neck sustaining 33% of the exposures. The most frequent body fluid exposure was to blood (64%), interestingly from a dental perspective blood containing saliva accounted for almost 6% of the exposures. Other exposures were from peritoneal fluid, tracheal secretions, amniotic fluid and blood containing faeces.11 Only, one fifth (21%) of the exposed HCWs participated in post exposure prophylaxis for HIV. As reported in the study, “There was no seroconversion among the HCWs, leading to a seroconversion rate of 0% (n=0).”11

In this study, a percutaneous injury was defined as a needle stick injury, laceration injury, or any injury that leads to a break in the skin barrier resulting in exposure to an HIV contaminated body fluid.11 A mucocutaneous exposure was defined as a splash that results in exposure of mucous membranes or skin to HIV positive body fluids.11

The investigators also undertook a world -wide literature review of HIV-seroconversion rates. They were able to identify 17 reports spanning the period 1983-2015 in which there were 7,652 instances of HCWs being exposed to HIV positive body fluids.11 From this number there were 9 documented cases of seroconversion following percutaneous exposures. However, the validity of these seroconversions should be questioned as 8 occurred between 1983 and 1997 and were based on outdated data, while the remaining instance reported in 2015 was extrapolated from a Columbian health registry. The Columbian case appears to be an outlier for the following reason. From 1998 to 2015 there were 8 published studies involving a total of 2,863 potentially vulnerable exposures to HIV with no seroconversions occurring after percutaneous injuries apart from the Columbian example.11

The injury most commonly associated with a percutaneous exposure is from a significant volume of blood within a relatively large bored hollow needle being inoculated deep into the flesh or muscle of the HCW.12,13 The needle stick type injuries sustained by dental personnel do not satisfy these criteria, nevertheless they were included in the above definition of percutaneous injuries. With this understanding and the almost non-existent rate of seroconversion following percutaneous injuries, current world-wide experiences support the conclusion that dental personnel are not at risk of acquiring HIV infections from professionally acquired percutaneous exposures to HIV positive body fluids. This should be a satisfactory determination since the gloves worn by dental staff do not prevent needle stick type injuries.14

Among the 7,652 world-wide instances where the possibility for HIV transmission occurred, 1,365 were specifically identified as being due to mucocutaneous exposures.11 The only instance where such an event resulted in HIV seroconversion was when an Italian nurse experienced a mucous membrane exposure to a large quantity of blood from an HIV-positive hemophilic patient- an unlikely event in dentistry.15 The fact that 1,364 mucocutaneous exposures did not result in the occupational transmission of HIV is convincing evidence that wearing of masks and gloves by dental personnel to prevent such routes of infection are unnecessary precautions.

Based on their own findings and analysis of the world-wide data, the authors of the new report have calculated that the realistic rate for percutaneous injuries resulting in seroconversion is 0.18% not 0.3% as previously reported.11 The 1,365 examples of mucocutaneous exposures with only one seroconversion gives a seroconversion rate for mucocutaneous injuries of 0.07% as opposed to the traditional rate of 0.09%.11

These new findings support three conclusions. One, there never was a large underestimate of occupationally acquired HIV infection among health care workers. Two, Neiburger was correct as the justification for universal precautions was based purely on insignificant and overestimated risks to dentists from HIV/AIDS. Three, in the practice of their profession, dental clinicians and their staff are not at risk of acquiring HIV/AIDS from infected patients.

These realizations should release dentist from the restrictions of mandated infection control recommendations and authorize them to adopt precautions on a case by case basis predicated on individual health histories and proposed

The Illusion of Infection Control as Practiced by District Health Units
In recent months District Health Units throughout Ontario have been using SWAT like invasions of dental offices to enforce infection control. These cavalier raids are destroying professional reputations, causing undue panic among patients, raising the cost of dental care and will produce no appreciable benefits. The underlying reason for this is the adoption by Health Units of dictatorial judgements that do not reflect the nature of dental practice or the basic principles governing the discipline of infection control.

The necessity for and value of infection control requires it to be based on proactive surveillance of dental practices. This is not being done. Instead, Public Health inspectors have adopted a reactionary approach to infection control. Investigations are initiated on receipt of a possible violation of a decontamination process. If a check box investigation identifies a breach in decontamination protocols, the practice is closed down and patients tested for HIV, HBV and HCV. This is not infection control. It is a bureaucratic witch hunt since the inspectors have no idea if there is any relationship between the alleged infraction and those viral infections. It is a misinformed, expensive illusion of what infection control should be. It is one which has caused immeasurable suffering to diligent practitioners and unnecessary panic among their patients. These conclusions are supported by appreciating that none of the inspector determined decontamination failures has resulted in HIV, HBV or HCV infections.

District Health Units do have a role in ensuring adequate standards for dental infection control. However, this must be based on an honest and frank assessment of dental care associated infections free from the media hyperbole and political expediency generated by HIV/AIDS. In the meantime, until they fully appreciate that dental practices are not acute care hospital facilities, District Health Units would be well advised to stop subjecting dentists, their staff and patients to an illusion of infection control. OH

The author wishes to thank Dr. E. Neiburger for retrieving his “Letter to the Profession” and Mr. D. Crowe of the Alberta  Reappraising AIDS Society for accessing the recent 2017 report.

Disclaimer: A future article that will appear in Oral Health will provide a more detailed critique of District Health Units’ investigations.


  1. Hardie J, AIDS, Dentistry and the Illusion of Infection Control. Mellen Press, New York, 1995.
  2. Klein RS et al, Low occupational risk for HIV infection for dental professionals. {Abstract} In; Abstracts from the III International Conference on AIDS, June 1985.
  3. CDC Update: Acquired immunodeficiency syndrome and human immunodeficiency virus infection among health-care workers. MMWR 37,No 15:229-234; 1988
  4. Lubick HA et al, Occupational risk of dental personnel survey. J Am Dent Assoc 113: 10: 1986.
  5. Gerberding JL et al, Risks to dentists from exposure to patients infected with AIDS virus. In Abstracts of the 26th Interscience Conference on Antimicrobial Agents and Chemotherapy, Sept 28th–Oct 1st, 1986.
  6. Flynn NM et al, Absence of HIV antibody among dental professionals exposed to infected patients. West J Med 146: 439-442; 1987.
  7. CDC Recommendations for Prevention of HIV Transmission in Health-Care Settings. MMWR 36: No. 2S; 1987.
  8. Neiburger EJ, Quantifiable Risk in Dentistry: A Letter to the Profession. Oral Health, January 2001.
  9. Blackwell T, HIV risks on increase for health workers: study. Calgary Herald, 17th August, 2006.
  10. Government of Canada, HIV and AIDS in Canada: Surveillance Report to December 31, 2014.
  11. Nwaiwu CA et al, Seroconversion rate among health care workers exposed to HIV-contaminated body fluids: The University of  Pittsburgh 13-year experience. Am J Infect Control, 45(8):896-900; 2017.
  12. Ippolito G et al, Occupational Human Immunodeficiency Virus Infection in Health care Workers: Worldwide Cases Through September 1997. Clin Infect Diseases, 28: 365-383; 1999.
  13. CDC: Public health Service Guidelines for the Management of Health Care Worker Exposure to HIV and recommendations for Postexposure Prophylaxis. MMWR 47(RR-7): 1-29; 1998.
  14. Siew C et al, Percutaneous Injuries in Practicing Dentists. JADA, 126:1227-1234; 1995.
  15. Ippolito G et al, The Risk of Occupational Human Immunodeficiency Virus Infection in Health Care Workers Italian Multicenter Study, Arch Intern Med, 153(12):1451-1458; 1993.

Although retired from practice, Dr. Hardie maintains a thirty plus years interest in the discipline of infection control as it relates to dentistry. He has published extensively on the subject and has lectured on it and related subjects throughout North America and in the UK, Europe, the Middle and Far East.

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