Aerosol Production

The primary route of contracting Hepatitis B, C, or HIV in the dental office is through exposure to blood (bloodborne exposure), most commonly through percutaneous injury (e.g. a needlestick or puncture with a sharp object). The general population most commonly contracts these bloodborne pathogens through direct contact with blood or infected bodily fluids, unprotected sex, shared needles, and from an infected mother to child during delivery. These bloodborne pathogens are are not as easily spread through airborne contact. Airborne/respiratory disease such as TB, SARS, and MERS are much more of a concern than bloodborne pathogens when using ultrasonics. Ultrasonics are contra-indicated for those with respiratory illness.   You are correct that aerosols/droplets can linger for up to 30 minutes. The droplet evaporates into droplet nuclei which can become airborne again as dust particles. Well fitting PPE and standard/universal precautions are always your first line of defense. However, the literature indicates that pre-procedural rinsing (ideally with chlorhexidine) and high volume suction/evacuation are effective when used alone as well as together in reducing the microbial load of the aerosols produced during ultrasonic scaling. High volume suction has been shown to significantly reduce airborne pathogens up to 98%. The author, Stephen Harrell, states that high volume suction is a "mandatory infection control precaution" when using ultrasonics. He published an excellent article in Dimensions of Dental Hygiene several years ago (October 2003;1(6):16, 18, 20.) Although this article is 10 years old, the information is still relevant. Other more recent articles by SK Harrell include: "Airborne Spread of Disease--the Implications for Dentistry" in the J Calif Dent Assoc. 2004 Nov;32(11):901-6, and "Aerosols and Spatter in Dentistry: a Brief Review of the Literature and Infection Control Implications" in the J Am Dent Assoc. 2004 Apr;135(4):429-37. I hope these are helpful resources for you.   Many of the studies about aerosols in the dental operatory must be carefully examined. Most studies count organisms that can be cultured on a petri dish (aerobic bacteria) so most of the bacterial counts measured are non-pathogenic bacteria. Anaerobic bacteria are much more pathogenic and are difficult to measure on an agar plate. Also, viruses (like Hepatitis B, C, and HIV) cannot be cultured in this medium, so the method for many studies is flawed.   The CDC Guidelines are in the process of being updated. Look for an update coming in the next year or two. Pre-procedural rinsing will most likely be a topic that has been significantly updated as further research has been done on aerosols since the 2003 Guidelines. Stay tuned.