Regardless of the size or shape of the instrument-processing area, four basic areas govern the pattern of workflow. Instruments that are being processed should proceed in a single loop—from dirty, to clean, to sterile, to storage—without ever “doubling back” (Figure 8-2).

If the instrument-processing area is small, you can use signs that read, “Contaminated items only,” “Precleaning area,” “Cleaned items only,” “Sterile items only,” or “Sterilization area,” to separate contaminated and clean areas. This method works well to prevent mixing of contaminated and sterile items in a small sterilization area.

The holding solution may be any noncorrosive liquid. A commercial enzymatic solution that partially dissolves organic debris may be used (Figure 8-3). Dishwasher detergent also makes a good holding solution because it is low cost, low foaming, and readily available. It is neither cost-effective nor desirable to use a disinfectant alone as a holding solution. The dental professional should read and follow the manufactures instructions for use on the ultrasonic unit when choosing a solution.

The container must have a lid and must be labeled with both a biohazard label (because of the contaminated instruments) and a chemical label (because of the cleaner and/or detergent). The holding solution should be changed at least twice daily, more frequently if it becomes clouded.

Remember, a holding solution is necessary only when contaminated instruments cannot be processed immediately.

In the clean area, cleaned instruments and other dental supplies should be inspected, assembled into sets or trays, and wrapped or placed in packages for sterilization (Figure 8-4).

Clean instruments are not sterile and could still harbor pathogens. Instruments must be packaged and sterilized before being used on a patient.

Hand scrubbing is the least desirable method of cleaning instruments because it requires direct hand contact with the contaminated instrument. If you absolutely must hand-scrub instruments, adhere to the following precautions:

Note: Some states have specific infection control guidelines or Occupational Safety and Health Administration (OSHA) plans that prohibit hand scrubbing of instruments. In these states, you must use an ultrasonic cleaner or machine cleaning.

Ultrasonic cleaners are used to loosen and remove debris from instruments. These cleaners also reduce the risk of hand injuries from cuts and punctures during the cleaning process (Procedure 8-1).

Puncture-resistant utility gloves, a mask, protective eyewear, and a protective gown should always be worn when the ultrasonic cleaner is used. To further limit contact with contaminated instruments, keep a set of tongs near the ultrasonic unit for removing instruments after the cleaning cycle (Figure 8-5).

The ultrasonic cleaner works by producing sound waves beyond the range of human hearing. These sound waves, which can travel through metal and glass containers, cause cavitation (formation of bubbles in liquid). The bubbles, which are too small to be seen, burst by implosion (bursting inward, the opposite of an explosion). The mechanical cleaning action of the bursting bubbles combined with the chemical action of the ultrasonic solution removes the debris from the instruments.

Instruments should be processed in the ultrasonic cleaner until they are visibly clean. The time may vary from 5 to 15 minutes, depending on the amount and type of material on the instruments, and the efficiency of the ultrasonic unit. Instruments in plastic or resin cassettes require slightly longer cleaning times because the cassette material absorbs some of the ultrasonic energy.

You should use ultrasonic solutions that are specially formulated for use only in the ultrasonic cleaner. Some ultrasonic cleaning products have enzyme activity (Figure 8-6). Other ultrasonic cleaning products have antimicrobial activity, which reduces the buildup of microbes in solutions with repeated use. Antimicrobial activity does not disinfect the instruments; it merely prevents microorganisms from increasing in number.

Do not use other chemicals such as plain disinfectants in the ultrasonic cleaner. Some disinfectants can “fix” the blood and debris onto the instruments, making subsequent cleaning more difficult. Specific ultrasonic solutions are available that remove difficult materials, such as cements, tartar, stains, plaster, and alginate (Figure 8-7). Refer to the ultrasonic unit manufacturer’s instructions regarding the specific solution to be used.

Similar to the holding solution, the ultrasonic cleaning unit should be labeled with both a chemical label and a biohazard label because it contains a chemical along with contaminated instruments.

Automated instrument washers/disinfectors look and work similar to a household dishwasher. However, the U.S. Food and Drug Administration (FDA) must approve them for use with dental instruments (Figure 8-8).

Automated washing/disinfecting units use a combination of very hot water recirculation and detergents to remove organic material. Then the instruments are automatically dried. These units are classified as thermal disinfectors because they have a disinfecting cycle that subjects the instruments to a level of heat that kills most vegetative microorganisms.

Instruments processed in the automatic washers/disinfectors must be wrapped and sterilized before use on a patient.

An alternative to using rust inhibitors is to dry the instrument thoroughly using dry heat or unsaturated chemical vapor sterilization (see “Chemical Vapor Sterilization” section), which does not cause rusting.

Hinged instruments may need to be lubricated to maintain proper opening. Take care to remove all excess lubricant before heat sterilization.

Specific types of packaging material are available for each method of sterilization. You should use only the type of packaging material designed for the particular method of sterilization that you are using (Box 8-2).

A wide variety of sterilization packaging materials are available. Self-sealing or heat-sealed “poly” bags or tubes provide an excellent wrap (Figure 8-9). In addition, paper wraps and cloth wraps are available. If the package is not the self-sealing type, you should use only sterilization indicator tape to seal the package.

Never use safety pins, staples, paper clips, or other sharp objects that could penetrate the packaging material.

The instruments are now ready for the sterilization process.