California Dental Board Approved: Infection Control (2 Units)

Sterilization and Disinfection of Patient Care Items


Cleaning involves the physical removal of organic matter to reduce microbial growth prior to the reduction and/or destruction of microbes through the sterilization or disinfection process. Organic matter may interfere with the action of antiseptics, disinfectants and sterilants by preventing adequate penetration. Soap and water with friction is the standard. Cleaning is the basic first step in all decontamination processes.

Sterilization involves the removal or destruction of all microorganisms and their spores.

Disinfection involves the reduction in number and type of microorganisms -

  • High-level includes pasteurization or use of gluteraldehyde. All life is destroyed except spores. Items that touch mucous membranes should receive high-level disinfection i.e. flexible endoscopes, laryngoscopes and other similar instruments.
  • Intermediate level hospital-grade disinfectant - an Environmental Protection Agency (EPA) approved Tuberculocidal cleaner/disinfectant. Items that touch mucous membranes or skin that is not intact should receive intermediate- level disinfection i.e. thermometers, hydrotherapy tanks.
  • Low-level sanitizers reduce bacteria to what is considered a "safe level". Items that touch intact skin should receive low - level disinfection i.e. stethoscopes, beds, whirlpools, and equipment which are non-invasive to patients.

Antisepsis is the inhibition of microorganism's growth on living tissue such as skin preparation before vascular line insertion or other invasive procedure. Alcohol, chlorhexidine, and Iodophors, i.e., betadine are most frequently used solution for antisepsis. Germicidal chemicals used for antisepsis are not generally adequate for decontaminating environmental surfaces. There are three categories of patient-care items depending on their intended use and the potential risk of disease transmission.

Critical items penetrate soft tissue or contact bone, the bloodstream, or other normally sterile tissues of the mouth. They have the highest risk of transmitting infection and should be heat-sterilized between patient uses. Alternatively, use sterile, single-use disposable devices. Examples include surgical instruments, periodontal scalers, periodontal probes, scalpel blades and surgical dental burs.

Semi-critical items contact only mucous membranes and do not penetrate soft tissues. As such, they have a lower risk of transmission. Examples of these are mirrors, amalgam condensers, impression trays and x-ray aiming devices,

Because most items in this category are heat-tolerant, they should be heat sterilized between patient uses. For heat-sensitive instruments, high-level disinfection is appropriate.

Dental handpieces are a special case. Even though they do not penetrate soft tissue, it is difficult for chemical germicides to reach the internal parts of handpieces. For this reason, they should be heat sterilized using a steam autoclave or chemical vapor sterilizer.

Noncritical instruments and devices only contact intact skin, which serves as an effective barrier to microorganisms.

These items carry such a low risk of transmitting infections that they usually require only cleaning and low-level disinfection. If using a low-level disinfectant, according to OSHA, it must have a label claim for killing HIV and HBV. However, if an item is visibly bloody, it should be cleaned and disinfected using an intermediate-level disinfectant before use on another patient. Examples of instruments in this category include X-ray head/cones, facebows, pulse oximeters, and blood pressure cuffs.

Instrument Processing Area

Most instrument cleaning, disinfecting, and sterilization should occur in a designated central processing area to control both quality and personnel safety.

To prevent cross-contamination, the instrument processing area should be physically or spatially divided into regions for cleaning, packaging, sterilization, and storage.

  • In the cleaning area, reusable contaminated instruments are received, sorted, and cleaned.
  • The packaging area is for inspecting, assembling, and packaging clean instruments in preparation for final sterilization.
  • The sterilization and storage area contains the sterilizers and related supplies, incubators for analyzing spore tests (if performed in office-although some states require using a testing service), and can contain enclosed storage for sterile items and disposable (single-use) items.


As noted above in the definitions, cleaning is the first step in a decontamination process.

Automated or mechanical cleaning equipment, such as ultrasonic cleaners, instrument washers, and washer-disinfectors, are commonly used to clean dental instruments. Automated cleaners increase the efficiency of the cleaning process and reduce the handling of sharp instruments. After cleaning, instruments should be rinsed with water to remove chemical or detergent residue.

If manual cleaning is necessary, soak instruments in a rigid container filled with detergent, disinfectant/detergent, or an enzymatic cleaner. This step prevents drying of patient material and makes cleaning easier and less time consuming.

  • Do not use high-level disinfectants/sterilants (e.g., glutaraldehyde) as instrument-holding solutions.
  • To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty, utility gloves (i.e., not patient care gloves) when handling or manually cleaning contaminated instruments and devices. To protect against splashes, a facemask, eye protection or face shield, and a gown or jacket should be worn.

Preparation and Packaging

After thorough cleaning and drying of instruments, critical and semi-critical instruments that will be stored before use should be wrapped or placed into container systems prior to heat sterilization. This step protects items from contamination after the sterilization cycle and during storage.

Open or unlock hinged instruments so that all surfaces are exposed.

Place a chemical indicator inside each wrapped package. If the indicator cannot be seen from the outside, place another indicator (e.g., indicator tape) on the outside of the package.

Always wear heavy-duty, puncture-resistant utility gloves while inspecting and packaging instruments.

Heat-Based Sterilization

There are three types of heat sterilization methods commonly used in dentistry.

  1. Steam under pressure (autoclaving). There are two types of tabletop steam autoclaves: o In most commonly used gravity displacement sterilizers, steam enters the chamber and unsaturated air is forced out of the chamber through a vent in the chamber wall. o In contrast, pre-vacuum sterilizers are fitted with a vacuum pump to create a vacuum in the chamber and ensure air removal from the sterilizing chamber and load before the chamber is pressurized with steam. This method improves the speed and efficiency of the sterilization process.
  2. Dry heat sterilizers are either static air (convection or FDA-approved oven type) or forced air (rapid heat-transfer).
  3. Unsaturated chemical vapor sterilizers use a proprietary formula of alcohol/formaldehyde.

With all of these methods, always use FDA-approved devices and closely follow the manufacturer's instructions for proper use.

Liquid Chemical Sterilant/Disinfectant

Heat-sensitive instruments can be sterilized or high-level disinfected by soaking them in a liquid chemical germicide cleared by the FDA. However, exposure to these powerful and toxic chemicals can be harmful to DHCP and patients if the manufacturer's instructions for use and safety precautions are not followed precisely. For these reasons, CDC encourages the use of heat-tolerant or disposable alternatives.

Sterilization Monitoring - Types of Indicators

Proper monitoring of sterilization procedures should include a combination of process indicators, including the following:

  • Mechanical-involves assessment of cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer.
  • Chemical-uses sensitive chemicals that change color when a given parameter is reached (e.g., heat-sensitive external tape, internal chemical indicator strip).
  • Biological-this method is the most valid method for monitoring the sterilization process because it assesses the process directly. It does so by using the most heat-resistant microorganisms and not by using indicators that only test the physical and chemical conditions necessary for sterilization.

Mechanical and chemical indicators should be assessed with each load. If either mechanical indicators or internal or external chemical indicators indicate inadequate processing, items in the load should not be used until reprocessed.

Biological indicators should be assessed at least once a week.

Storage of Sterile and Clean Items and Supplies

DHCP have a choice about how they maintain their instrument storage area - either date- or event-related shelf-life practices. In date-related packing, every sterilized package is expiration-dated and the instruments are used on a "first in, first out" basis. In event-related practice, the contents of a sterilized package should remain sterile indefinitely unless some event, for example, torn or wet packaging material, causes it to become potentially contaminated. It is still useful to place the date of sterilization and identify the sterilizer used if multiple sterilizers are utilized in the office. In case of sterilization failure, this information would facilitate retrieval of processed items.

  • Examine each package. If it is damaged in any way, items should be re-cleaned, re-wrapped, and re-sterilized. Even if an event-related approach is used, all packages should be labeled with the date of sterilization and which sterilizer was used, should a sterilization failure occur.
  • Store all sterile and clean items and supplies in dry, closed, or covered cabinets.

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