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The process of instrument sterilization and recirculation needs to be safe, consistent, efficient, and repeatable. Our dental environment must protect the patient, the dental auxiliaries, and the dentist from contact with any potentially infectious diseases.

Automated instrument-cleaning machines promise safer working environment and reduced costs.

Omelan Kotsopey, DMD

The process of instrument sterilization and recirculation needs to be safe, consistent, efficient, and repeatable. Our dental environment must protect the patient, the dental auxiliaries, and the dentist from contact with any potentially infectious diseases.

In 1952, the ADA published the first infection-control guidelines in Accepted Dental Remedies. Chemical agents for disinfection were described and precleaning of instruments and heat sterilization were emphasized. In 1970, the U.S. Congress created OSHA, which promptly published guidelines concerning sterilization protocol for protection of the dental staff. In 1986, the Centers for Disease Control (CDC) published the first comprehensive dental infection-control guidelines. Blood, saliva, and gingival fluid were considered to be infectious and the use of universal precautions was mandated.

Today, every dental office is professionally obligated to comply with these recommendations. Strict adherence to barrier precaution and infection control is not an option. Safety of the patient, staff, and dental professional is the top priority.

Instrument recirculation begins immediately after a dental procedure is completed. Wearing OSHA-recommended, personal-protective equipment - such as heavy-duty utility gloves, masks, protective eyewear, and protective clothing - a staff member removes the contaminated instruments and takes them to a specifically defined area in the office.

As defined by CDC, OSHA, and the ADA, the following steps are to be taken to clean and sterilize instruments before returning them to circulation:

x- After a procedure, instruments should be visually inspected for gross debris and hand-scrubbed, if needed. Ideally, the instruments should then be placed into an instrument cassette for processing.

x- To keep biological matter from drying out and adhering to instrument surfaces, the instruments should be placed into a holding tank for presoaking. The ideal presoaking solution is a mildly alkaline solution with a pH of 10.0-10.5 and heated to a temperature of 110-120 degrees.

x- The instruments then are removed from the presoaking solution, rinsed with clean water, and carefully placed into the basket of an ultrasonic cleaner.

x- A ultrasonic instrument cleaner, capable of handling the instrument load, is activated and the instruments are thoroughly cleaned. Upon completion, the instruments are removed and rinsed with water.

x- The instruments then are dried, packaged, sterilized, and stored.

This process of instrument processing, as recommended by the CDC, OSHA, and the ADA, is effective, but it does have some weak points. This article will point them out and offer ways to resolve them.

The problems

x- Hand-scrubbing instruments - Percutaneous and permucosal exposure to blood and other body fluids poses the single greatest risk of transmission of HIV, hepatitis (B, C, and D), and other bloodborne diseases from patient to health-care provider. Hand scrubbing of instruments is potentially very dangerous and should be totally avoided.

The use of ultrasonic cleaners is recommended to increase the efficiency of cleaning and to reduce the handling of sharp instruments. Ultrasonic cleaners have been shown to be up to 16 times more effective than hand scrubbing.

Question: When scrubbing is needed, is it done properly using the submarine technique (the instruments are scrubbed while being totally submersed) with heavy-duty gloves? Or, is it done under a running faucet by a staff member wearing vinyl gloves?

x- Loose instruments - Handling of loose instruments should be kept to a minimum due to risk of percutaneous injury. Staff members must wear heavy-duty utility gloves at all times while handling the instruments. Disposable vinyl gloves should not be used. With the addition of an instrument-cassette system, instrument handling by staff can be dramatically reduced.

Question: Since the heavy-duty utility gloves used in the handling of contaminated instruments are reusable, should they be routinely sterilized so they do not become a point of cross-contamination?

x- The enzymatic presoaking tank - The presoak solution`s efficiency depends on the amount of bioburden, proper dispensing of concentrate, and accurate monitoring of solution use.

Question: Can we expect the staff to accurately monitor this chemical bath for efficacy or does the staff use the "looks dirty" method before changing the solution?

x- Rinsing - When removing instruments from the presoaking tank or the ultrasonic cleaner, the staff must be careful to avoid dripping or splashing solution as it is carried to the sink for rinsing.

Question: After rinsing instruments in the sink, should the sink also be disinfected?

x- Ultrasonic cleaning - Depend-ing on instrument load, actual time of cleaning, and solution strength, ultrasonic cleaning can vary from one cleaning cycle to the next. For effective ultrasonic cleaning, time must be allowed for solution degassing as well as an adequate length of time for effective cleaning.

Question: Can we expect reliable instrument cleaning in a randomly timed, overloaded, underpowered ultrasonic cleaner with cold solutions?

x- Drying - Drying of instruments is necessary in all methods of sterilization. Instruments should be carefully laid out for air-drying or placed into a commercially available drier. Patting or wiping instruments dry introduces the obvious danger of percutaneous injury and should be avoided.

Question: Does the dental staff have the time and capability to safely and thoroughly dry instruments before packaging and sterilization?

x- Draining of solutions - When contaminated solutions need to be changed, take caution to not spill or splash the solution while draining it into the sink.

Question: Are the presoaking and ultrasonic tanks routinely disinfected before fresh solution is added?

Instrument processing must be taken very seriously. The dental office needs to be adequately equipped and the staff must be properly trained to responsibly handle contaminated instruments. The dentist must allocate adequate time for the staff to accomplish instrument recirculation safely, consistently, and reliably.

In a recent survey, general practitioners indicated that they would like to see post-treatment, instrument-processing techniques take less time, less staff effort, and provide guaranteed results.

The fact that infection-control procedures are not direct revenue-generating techniques keeps doctors alert for more economical and more automated methods of controlling cross-contamination.

Today`s solution

To minimize the human factor in instrument processing, new automated ultrasonic cleaning machines have been developed. They combine a heated presoaking tank, a powerful ultrasonic cleaning tank, and a hot-air drying tank into a single unit.

Designed to minimize staff exposure to bloodborne pathogens, these machines maximize office productivity by eliminating the need for manual cleaning and providing consistent, repeatable cleaning of instruments.

With an automated instrument-cleaning system, the following functions are performed:

x- Precise dispensing of enzymatic concentrate

x- Automatic dilution of the concentrate with water

x- Heating of presoak solution for maximum enzymatic efficiency

x- Preset-timed ultrasonic cleaning of the instrument load

x- Automatic drainage of the cleaning solution

x- Refilling of the tank with water for proper rinsing

x- Ultrasonic activation of the continually flowing rinse water

x- Draining of the rinse water

x- Thorough hot-air drying

Instruments are never touched during the entire cleaning process prior to packaging and sterilization.

Labor savings

In a dental office with one dentist and a hygienist, the staff will spend approximately 260 minutes per day cleaning instruments. With the use of an automated cleaning system, the time necessary for instrument processing is shortened to 85 minutes, potentially saving the office $8,750 or more per year (assuming 250 workdays @ $12/hour).

Dollar savings aside, the advantage of these systems is that they free up staff time (up to three hours per day). The time saved cleaning instruments can be used to assist with more revenue-generating work.

Space savings

Automated cleaning systems save valuable space. No longer do you need eight or more linear feet of cabinet space to accommodate a sterilization center. An entire sterilization center can be built in five linear feet of wall space. An automated cleaning system is designed to fit into an 18-inch base cabinet (the counter cutout being only 10" x 15.5"), with the remaining counterspace accommodating the sterilizers and workspace. The office-sterilization center now is compact, efficient, and can fit into most offices.


The key feature in using an automated ultrasonic cleaner is safety. These machines eliminate dispensing and disposing of cleaning solutions. They eliminate the transportation of instruments from presoaking tanks to ultrasonic tanks, and from rinsing sinks to the drying table. They provide the dental office with consistent and repeatable instrument cleaning. Above all, the machines significantly raise the safety level for the dental staff during the instrument-recirculation process.

Dentistry enters the new millennium with wonderful, new restorative materials, tremendous periodontal advancements, and fantastic computer-aided products and techniques. Our instrument recirculation and sterilization process is becoming simpler and safer.

With the use of sterilization cassettes, automated instrument-cleaning machines, and time-saving sterilizers, the work environment is now safer and our costs can be significantly reduced.

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