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Infection Control

Frequently Asked Questions - Sterilization — Cleaning

What is a central instrument processing area?

In dental health care settings, all instrument cleaning, disinfecting, and sterilizing should occur in a designated central processing area in order to more easily control quality and ensure safety. The instrument processing area should be physically divided into sections for 1) receiving, cleaning, and decontamination; 2) preparation and packaging; 3) sterilization; and 4) storage. This division is designed to contain contaminated items in an area designed specifically for cleaning, thus preventing contamination of the clean areas where packaging, sterilization, and storage of sterile items occurs. Reusable contaminated instruments and devices are received, sorted, and cleaned in the cleaning area. The packaging area is for inspecting, assembling, and packaging clean instruments in preparation for final processing. The sterilization and storage areas contain the sterilizers and related supplies, as well as incubators for analyzing spore tests, and can contain enclosed storage for sterile items and disposable (single-use) items. When it is not possible to have physical separation of these areas, clearly labeling each area (e.g., from contaminated to sterile) might be satisfactory if the personnel who process the instruments are trained in work practices to prevent contamination of clean areas.

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Why must instruments be cleaned before being sterilized?

Cleaning should precede all disinfection and sterilization processes. Cleaning involves the removal of debris (organic or inorganic) from an instrument or device. If visible debris is not removed, it will interfere with microbial inactivation and can compromise the disinfection or sterilization process.

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Which is the best method for cleaning instruments, manual (e.g., scrubbing instruments with a brush) or automated?

Debris can be removed from an instrument either by scrubbing the instrument manually with a surfactant or detergent and water or by using automated equipment (e.g., ultrasonic cleaner, washer-disinfector) and chemical agents. After cleaning, instruments should be rinsed with water to remove chemical or detergent residue. Splashing should be minimized during rinsing and cleaning.
Considerations in selecting cleaning methods and equipment include their effectiveness, their compatibility with the items to be cleaned, and the occupational health and exposure risks they pose. Because instruments cleaned with automated cleaning equipment do not need to be presoaked or scrubbed, the use of automated equipment can increase productivity, improve cleaning effectiveness, and decrease worker exposure to blood and body fluids. Thus, using automated equipment can be more efficient and safer than manually cleaning contaminated instruments.

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How do I perform manual cleaning?

If manual cleaning is not performed immediately, instruments should be placed into a container and soaked with a detergent, a disinfectant/detergent, or an enzymatic cleaner to prevent drying of patient material and make manual cleaning easier and less time consuming. CDC also recommends using long-handled brushes to keep the hand as far away as possible from sharp instruments.

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What type of personal protective equipment is necessary when cleaning instruments and surfaces?

Instruments should be handled as though contaminated until processed through the sterilization cycle (unless the instrument has been processed with a thermal washer/disinfector that has a high-level disinfection cycle). To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty utility gloves when handling or manually cleaning contaminated instruments and devices. Because splashing is likely to occur, they should also wear a facemask, eye protection or face shield, and gown or jacket. Employees should not reach into trays or containers holding sharp instruments that cannot be seen. To reduce their risk of injury, they should instead remove instruments using forceps or empty them onto a towel.

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Selected References and Additional Resources


CDC. Guidelines for Infection Control in Dental Health-Care Settings, 2003. MMWR, December 19, 2003:52(RR-17).

Harte JA, Molinari JA. Sterilization procedures and monitoring. In: Molinari JA, Harte JA, eds. Practical Infection Control in Dentistry, 3rd ed. Baltimore: Lippincott Williams & Wilkins, 2010;148–170.

Miller CH, Palenik CJ. Instrument processing. In: Miller CH, Palenik DJ, eds. Infection Control and Management of Hazardous Materials for the Dental Team,4th ed. St. Louis: Mosby: 2010;135–167.

Miller CH, Tan CM, Beiswanger MA, Gaines DJ, Setcos JC, Palenik CJ. Cleaning dental instruments: measuring the effectiveness of an instrument washer/disinfector. Am J Dent 2000;13:39–43.

US Department of Labor, Occupational Safety and Health Administration. 29 CFR Part 1910.1030. Occupational exposure to bloodborne pathogens; needlestick and other sharps injuries; final rule. Federal Register 2001;66:5317–5325. Updated from and including 29 CFR Part 1910.1030. Occupational exposure to bloodborne pathogens; final rule. Federal Register 1991;56:64003–64182.

US Department of Labor, Occupational Safety and Health Administration. Enforcement procedures for the occupational exposure to bloodborne pathogens. Washington, DC: US Department of Labor, Occupational Safety and Health Administration, 2001; Directive Number. CPL 02-02-069.

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