CDC NATIONAL AIDS HOTLINE TRAINING BULLETIN #17 - November 25, 1992
Centers for Disease Control and Prevention

1. What are CDC's recommendations for the sterilization of dental handpieces, prophy angles, and other dental instruments?

Recommendations for infection control in dentistry state that, between patients, all heat-tolerant instruments should be cleaned and then treated by a sterilization procedure utilizing heat, such as steam autoclave. These sterilization procedures should be undertaken according to the manufacturer's instructions. Heat treatment is particularly important for those instruments such as the high-speed handpiece and reusable prophy angles where physical access to the internal and external surfaces may limit the effectiveness of liquid chemical germicides for disinfection or sterilization.

2. Is CDC currently updating its recommendations for infection control in dentistry?

CDC is updating current recommendations for infection control in dentistry. Recommendations for infection control practices for dentistry were first published in 1986. In 1989 an infection control handbook that outlined practical decontamination procedures in the dental office was published. Although the basic principles of infection control remain unchanged, the emergence of new technologies, materials, equipment, and data require continual evaluation of current practices.

3. Can HIV be transmitted from an infected patient to an uninfected patient through the reuse of dental instruments?

Reusable medical or dental instruments, contaminated with blood or tissue during use, may have the potential to transmit infection to a subsequent patient if these instruments are not appropriately cleaned and disinfected or sterilized after each use. Investigators at CDC are not aware of any studies that confirm the transmission of a bloodborne pathogen, such as hepatitis B virus (HBV) or human immunodeficiency virus (HIV), through contaminated dental equipment. Patient-to-patient transmission of a bloodborne pathogen, HBV, has been identified and reported in other health care settings, however, where common-source vehicles were contaminated.

4. What was the most likely mechanism of transmission of HIV to five patients during dental treatment in a Florida practice.

Although the specific incident that resulted in HIV transmission to these patients remains uncertain, the epidemiologic evidence strongly suggests direct dentist-to- patient transmission rather than a patient-to-patient transmission of HIV through contaminated dental equipment, i.e. highspeed handpiece or prophy angles. For further information refer to "Transmission of Human Immunodeficiency Virus in a Dental Practice," Ciesielski C, et al., Annals of Int. Med., May 15, 1992.

5. Can CDC comment on a paper by Dr. David Lewis entitled "Cross-contamination potential for dental equipment." This paper was published in the November 21, 1992, issue of Lancet.

Dr. Lewis' study does not demonstrate transmission of disease, but reconfirms past observations that dental handpieces and other instruments, such as prophylaxis angles, potentially may be contaminated with patient material during use. One aspect of his study involved using dental instruments on patients infected with HIV, cleaning and disinfecting the external surfaces of the instruments, and then employing a very sensitive laboratory technique (i.e. polymerase chain reaction) to detect residual HIV genetic material from the internal surfaces; the laboratory technique used in this aspect of the study does not distinguish between live and dead HIV particles. This study supports CDC recommendations (1986) for appropriate cleaning and sterilization of all dental instruments.

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