Instrument Sterilization for Contemporary Dental Practices

By Rebecca Stone February 20, 2019

In today’s dental practices, infection control is a top concern. While an important part of the scenario, disinfection is just one aspect of the infection control protocol. Sterilization is another. Typically used on noncritical surfaces, such as intact skin and operatory furniture, low- and intermediate-level disinfectants are generally incapable of annihilating all microbial contaminants. And most do not kill bacterial spores.1

To process semicritical and critical instruments, something stronger is needed, such as high-level disinfectants, or sterilants, and heat.


The semicritical category includes instruments and devices, such as mouth mirrors, impression trays and radiography sensors, that come into contact with mucous membranes or nonintact skin.2,3  Dental handpieces also fall into the semicritical category. Because it’s been found that handpieces can accumulate debris and fluids internally (only to spit them back out into your next patient’s mouth), the US Centers for Disease Control and Prevention (CDC) recommends that handpieces that can be removed from air and waterlines should be cleaned and heat sterilized per manufacturer instructions between patients. Cordless handpieces should be cleared by the US Food and Drug Administration (FDA), and offer validated manufacturer reprocessing instructions.1,2,4,5

In the event a handpiece is heat sensitive and doesn’t have FDA clearance with such instructions, the most recent recommendation is that it should not be used.1,2,4,5

Some manufacturers, however, are rising to the occasion and designing handpieces that will tolerate high temperatures for heat sterilization.

The “critical” designation applies to items that penetrate tissue and bone, such as surgical instruments and periodontal scalers. These items are typically purchased in a sterile state and, as they carry the greatest risk of cross-contamination, they should always be sterilized with heat.1,2,5

Methods of Instrument Sterilization

Ideally, both semicritical and critical instruments should be heat sterilized. If a semicritical item is heat sensitive, the CDC now advocates replacing it with a heat-tolerant or disposable version, or at least, using a barrier and processing it with a high- or intermediate-level disinfectant, that includes active ingredients such as glutaraldehyde, hydrogen peroxide, orthophthaldehyde, peracetic acid or hypochlorous acid/hypochlorite.1,5,6

Methods of sterilization for heat-stable instruments include steam under pressure (autoclave), chemical (formaldehyde) vapor, and dry heat. Other sterilization methods include ethylene oxide gas, hydrogen peroxide gas, plasma, ozone and radiation.1,3

Although dry heat sterilization does not promote corrosion in some metals as can steam heat autoclaving, the latter is common in dental practices. In fact, steam autoclaves are the recommended way to sterilize low-speed handpieces. This is because they can sterilize at lower temperatures ­— 275° F — versus their dry-heat counterparts, which sterilize at 320° F.

Don’t Forget the Isolation System

An important part of most dental armamentariums is an isolation system. Central to the Isolite, Isovac and Isodry systems is a flexible, transparent mouthpiece, which is designed to retract cheeks and tongues, protecting them from inadvertent injury and keeping them out of the field of operation. In addition, the mouthpiece offers bilateral, 360° evacuation to keep fluids at bay and shields the throat, preventing accidental aspiration.

Because the mouthpiece is single-use, there is no risk of patient cross-contamination. But while the mouthpiece can be tossed, the control head and vacuum hose must be cleaned and sterilized according to manufacturer instructions.

It is wise to stay abreast of CDC guidelines, and the Organization for Safety, Asepsis and Prevention for any relevant training opportunities. Your staff and patients will be the beneficiaries.



  1. Stone R. Chain of events. Mentor. 2017;8(12):20–25.
  2. Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM. Guidelines for infection control in dental health-care settings—2003. Available at: Accessed January 22, 2019.
  3. Rutala WA, Weber DJ, Healthcare Infection Control Practices Advisory Committee. Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008. Available at: Accessed January 22, 2019.
  4. Centers for Disease Control and Prevention. CDC Statement on Reprocessing Dental Handpieces, 2018. Available at: Accessed January 22, 2019.
  5. Centers for Disease Control and Prevention. Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care. Available at: Accessed January 22, 2019.
  6. Cuny EJ. Beneath the surface. Mentor. 2018;9(4):18–23.