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May 2009 | Dental Products Report
Clinical 360°: Infection Control  Protect against oral aerosols and splatter Maintain safety in the dental office by reducing the spread of microbes in oral droplets and aerosols. The set-up “Oral microbes spread in a dental office several ways. Even though this seldom causes any problems, we cannot say the associated risk of disease occurrence in patients and staff is zero. It is important to maintain safety in the office by minimizing the chances for disease transmission from oral microbe spread. This article addresses some of these mechanisms and the prevention of microbial spread by droplet and airborne modes.” —Chris H. Miller, PhD, team lead Despite precautions taken by dental office staff to keep the office clean and to practice environmental asepsis, the patient’s oral microbes must also be considered. When working on patients these microbes can be spread throughout the dental office via four main methods (see “Modes of disease spread,” at bottom of page). The nature of splatter and aerosol droplets Although most of the microbes in aerosols and splatter come from the patient, some come from untreated dental unit water that is sprayed into the patient’s mouth and subsequently aerosolized. There even is some evidence showing dental personnel can be infected with microbes originally present in dental unit water. Intraoral procedures associated with generating aerosols and splatter include cavity preps, restoration removal, grinding, tooth sectioning, prophylaxis, power scaling, polishing, air drying and water rinsing. Some extraoral work also may generate particles from contaminated items, including chairside grinding of crowns and some lab activities of grinding, brushing and polishing. Splatter: Size matters The particles exiting patients’ mouths are divided into two categories based upon size. Most particles are larger droplets referred to as splatter (sometimes called spatter). These droplets are more than 50 micrometers in diameter. Some are visible and can be noted as spots on one’s eyewear; some even may be felt landing on the skin or in the eyes. Despite their size, splatter droplets may settle out as far as 3 feet away from the patient, contaminating nearby operatory surfaces. The second category, aerosols, consists of the smaller particles exiting a patient’s mouth. Measuring less than 50 micrometers in diameter, aerosols tend to evaporate quickly into even smaller invisible particles called droplet nuclei that measure 1 to 5 micrometers in diameter and may contain microbes. Survival of the microbes depends upon their resistance to drying and the humidity and air temperature. These small particles can remain airborne for minutes to hours and even longer in some instances. If any microbes in the nuclei remain viable after the evaporation process, these nuclei can serve as a source of airborne infection if inhaled. They are small enough to be inhaled into the alveoli of the lungs, which have an exclusion limit of 5 micrometers. Stop microbe spread Masks. A surgical mask safeguards the user’s mouth and nose from direct contact with the larger particles of a patient’s oral droplets and splatter that might harbor infectious agents. The mask also protects the patients from microbes generated by the wearer. Surgical dental masks offer filtration properties of at least 95% Bacterial Filtration Efficiency (BFE) or Particulate Filtration Efficiency (PFE). However, because most surgical masks “leak” (do not tightly fit the face, allowing air to escape) around the edges, they are not a reliable safeguard against airborne infections such as tuberculosis. To receive this advanced level of respiratory protection, the user should wear a respirator-type mask that is fit-tested. Although concerns do exist about surgical masks and their effectiveness in preventing microbe spread from patient aerosols, the Centers for Disease Control and Prevention’s (CDC’s) position has remained unchanged for the past six years, since the organization first published Guidelines for Infection Control in Dental Health-Care Settings—2003. CDC guidelines recommend when performing splatter- and/or aerosol-generating procedures, a mask and eye protection (either a face shield or goggles) should be worn. CONTINUED ON NEXT PAGE
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