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Inside Dental Hygiene
September 2019
Volume 15, Issue 4

Safety in Sterilization

Managing Your Handpiece Protocols

Catherine Paulhamus,MA

For many patients, a dental appointment is full of uncertainty. Concerns about the doctor's findings, treatment costs, pain or discomfort, or even embarrassment about their oral hygiene are all part of the experience. But what they don't expect to worry about is cross contamination from the handpieces. They trust that there is a professional level of flawless, state-of-the-art sterilization in place.

Dental health-care personnel (DHCP) are responsible for controlling the risks and ensuring a safe environment for patients to be treated. It's a never-ending cycle, as infectious microorganisms continually enter the practice through patients and staff, while new technologies, products, and procedures need to be implemented safely, under a complicated system of regulations (both state and federal).

Dental teams can protect patients by staying informed and committed to infection prevention practices. Guidelines are updated. Regulations change. Evidence-based practices are introduced. DHCP cannot simply rely on what they learned in school or during their last continuing education course. For example, last year the American Dental Association (ADA) and the Centers for Disease Control and Prevention (CDC) moved to clarify handpiece infection control guidelines, as there were questions about heat sterilization.1

Are You Up to Speed?

On appropriate oral healthcare websites, DHCP are posting questions about variations in sterilization protocols, often expressing how they're concerned when a practice does not seem to be particularly knowledgeable or vigilant. They should be concerned. Patients are scared and angry at the thought of being infected in a healthcare setting, especially at the dentist, where often uncomfortable procedures expose them to blood and saliva.

When a dental team treats infection control as non-critical, they are risking a breach that may jeopardize a patient or employee's safety, while exposing the practice to liability and media attention.

According to the CDC, handpieces are categorized as semicritical items: those that come in contact with mucous membranes or non-intact skin. "Dental handpieces and associated attachments, including low-speed motors and reusable prophylaxis angles, should always be heat sterilized between patients and not high-level or surface disinfected. Although these devices are considered semicritical, studies have shown that their internal surfaces can become contaminated with patient materials during use. If these devices are not properly cleaned and heat sterilized, the next patient may be exposed to potentially infectious materials."2,3

Low-Speed, Not Low-Risk

To promote consistency and care in sterilization practices, infection control specialists believe that it's important for teams to understand the reasons behind these regulations. For example, the design of low-speed handpieces offers an opportunity for cross-contamination, as venting may allow for release of any internal contamination. Research published in the Journal of the American Dental Association, and cited by the CDC in its guidelines, reinforced the need for decontamination of low-speed handpieces. In one study, the authors investigated whether the interior of low-speed handpiece/prophy-angle systems becomes contaminated during operation. In the 160 tests of handpieces contaminated at the prophy cup end, the spores traveled into the motor gears 32 times (20%). In another 160 tests in which the motor gears were contaminated, the test bacterium traveled through the prophy cup in 75 instances (47%). This in vitro data suggested that low-speed handpiece motors can become contaminated internally during use with prophy angles. Also, internal contaminants appear to have been released from the handpiece.4

In a second in vivo study, the authors found at least 75% of the handpiece/prophylaxis angle systems used on 20 subjects had bacterial contamination for at least one cultured area. Of 420 specimens, 258 (61.4%) produced bacterial growth. Again, these data suggested that the internal surfaces of low-speed handpieces can become microbially contaminated during use with prophylaxis angles.5

Can Your Handpiece Take the Heat?

With the shift toward mandating sterilization and the media attention on cross-contamination exposures, DHCP need to ensure and simplify compliance to all regulations by employing heat sterilization tolerant equipment. Dental handpieces are medical devices regulated by the US Food and Drug Administration (FDA). For handpieces that are independent of air and waterlines, CDC recommends that DHCP follow current FDA regulations by using FDA-cleared devices and following the validated manufacturer's instructions for use for reprocessing (cleaning, lubricating, and/or sterilizing) these devices. It is incumbent upon the device manufacturer to provide sufficient instructions on how to prepare devices for use on the next patient.6

In short, if a dental handpiece cannot be heat sterilized and does not have FDA clearance with validated instructions for reprocessing, DHCP should not use that device.6

Even though patients do not usually come into a practice when they're visibly infectious, there is no way to know what they, or the team, may be harboring. An excess of caution, for the benefit of all, is warranted.


1. ADA News. ADA, CDC work together to clarify handpiece infection control recommendations. March 16, 2018.

2. Centers for Disease Control and Prevention. Guidelines for Infection Control in Dental Health-Care Settings - 2003. MMWR 2003;52(No. RR-17):20.

3. Centers for Disease Control and Prevention. Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care.Atlanta, GA: Centers for Disease Control and Prevention, US Dept of Health and Human Services; October 2016: 12.

4.  Chin JR, Miller CH, Palenik CJ. Internal contamination of air-driven low-speed handpieces and attached prophy angles. J Am Dent Assoc. 2006;137(9):1275-1280.

5. Herd S, Chin J, Palenik CJ, Ofner S. The in vivo contamination of air-driven low-speed handpieces with prophylaxis angles. J Am Dent Assoc. 2007;138(10):1360-1365.

6. CDC Statement on Reprocessing Dental Handpieces. April 11, 2018.

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