The Least Desirable Method Of Precleaning Dental Instruments Is

Workflow Pattern

  • Regardless of the size or shape of the instrument-processing area, four basic areas govern the pattern of workflow.
  • Processing of instruments should proceed in a single loop, from dirty to clean to sterile to storage, without ever “doubling back.”
  • If the instrument-processing area is small, you can use signs:
    • “Contaminated items only”
    • “Precleaning area”
    • “Cleaned items only”
    • “Sterile items only”
    • “Sterilization area”

How do signs enhance the workflow pattern in the processing area?

The signs should be posted in a sequential and systematic manner.

All signs should be laminated before being posted to facilitate easy cleaning.

Contaminated Area

  • All soiled instruments are brought into the contaminated area, the initial receiving area, where they are held for processing. Any disposable items that have not already been discarded in the treatment room are removed from the instrument tray and disposed of as contaminated waste.
  • Thorough cleaning should be done before all disinfection and sterilization processes. It should involve the removal of all debris and organic materials (e.g., blood and saliva).
  • The contaminated area contains clean protective eyewear and utility gloves, counter space, a sink, a waste-disposal container, holding solution, an ultrasonic cleaner, an eyewash station, and supplies for the wrapping of instruments before sterilization.

Are blood-soaked items such as gauze and cotton rolls discarded with the rest of the trash?

How do you remove debris from the soiled instruments?

Why is the use of an ultrasonic cleaner recommended?

Why is an eyewash station needed when protective eyewear is always worn?

Preparation and Packaging Area

In the area set aside for preparation and packaging area, cleaned instruments and other dental supplies should be inspected, assembled into sets or trays, and wrapped or placed in packages for sterilization.

A modern sterilization center.


What items would you expect to see in this area?

Holding Solution

  • If instruments cannot be cleaned immediately after a procedure, they should be placed in a holding solution to prevent the drying of blood and debris on the instruments.
  • The holding solution may be any noncorrosive liquid. A commercial enzymatic solution that partially dissolves organic debris may be used.
  • 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 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/detergent).
  • The holding solution should be changed at least twice daily and even more frequently if it becomes clouded.
  • Remember, a holding solution is necessary only when contaminated instruments cannot be processed immediately.

Why is a nonfoaming detergent recommended?

What could happen to the instruments if they are left in the holding solution too long?

How will you know if the holding tank solution has been changed or cleaned during the course of a busy day?

When should the solution be changed?

Use of the holding tanks and solution should not be part of the normal routine of instrument processing. The holding tanks are only used when time does not permit the completion of instrument-processing steps.

Commercial holding solutions are available for use in precleaning. (Courtesy of Biotrol International.)


Several commercial precleaning holding solutions are available, but they can be costly.

Generally these solutions are enzymatic detergent cleaners that dissolve blood and tissue within a few minutes in both room temperature and warm water.

Most enzymatic cleaners are only effective in warm water. They can be used as a presoak and in the ultrasonic cleaning unit.

Precleaning and Packaging Instruments

  • Instruments may be precleaned in one of three ways:
    • Hand scrubbing
    • Ultrasonic cleaning
    • Instrument-washing machine

Which of these three precleaning methods is least desirable? Why?

Which method is least cost-effective?

Hand Scrubbing

Hand scrubbing is the least desirable method of cleaning instruments because it requires direct hand contact with the contaminated instrument.

As discussed earlier, injury can occur during the handling and scrubbing of sharp instruments.

If adequate ultrasonic or instrument washing equipment is unavailable, what would you do?

Hand Scrubbing Instruments

  • Wear goggle-type eyewear and puncture-resistant gloves in addition to your your protective clothing. Clean only one or two instruments at a time.
  • Use only a long-handled brush, preferably one with a hand guard or wide surface.
  • Keep items above the waterline; fully immersing them in a basin of soapy water interferes with your ability to see the sharp ends.
  • Allow instruments to air-dry or carefully pat them with thick toweling. To decrease the risk of accidental injury, never rub or roll instruments in a towel.

If you absolutely must hand-scrub instruments, you must take the precautions listed on this slide.

Remember to take care while scrubbing to minimized the risk of injury.

Scrub the instruments under running water to help eliminate aerosol production and to force debris down the drain.

Ultrasonic Cleaning

  • Ultrasonic cleaners are used to loosen and remove debris from instruments. These cleaners also reduce the risk of cuts and punctures to the hands during the cleaning process.
  • Puncture-resistant utility gloves, a mask, protective eyewear, and a protective gown should always be worn when the ultrasonic cleaner is being used.
  • To further limit contact with contaminated instruments, keep a set of tongs near the ultrasonic unit with which to remove instruments after the cleaning cycle.

Use of an ultrasonic cleaner is the most desirable method for removing debris and blood from dental instruments.

Remember to submerge the instruments completely in the ultrasonic solution.

It is important to keep the ultrasonic cleaner covered while it is in use to reduce splatter and contaminated aerosols.

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Note how keeping the lid in place during use will minimize additional exposure of aerosols or splatter in the dental office.

The ultrasonic solution may need to be changed several times during the day, depending on the number of instrument being cleaned. The solution should always be changed at the end of the day.

Ultrasonic Cleaning

  • 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).
  • 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.

Remember to use caution when loading the ultrasonic unit. Overloading the unit will inhibit the ability of the bubbles to collapse and create the turbulence necessary to effectively clean the surface of all of the instruments.

What variables affect the time required to clean instruments in an ultrasonic unit?

Ultrasonic Cleaning Solutions

  • You should only use ultrasonic solutions that are specially formulated for use in the ultrasonic cleaner.
  • Some ultrasonic cleaning products have enzyme activity.
  • Other ultrasonic cleaning products have antimicrobial activity, which reduces the buildup of microbes in the solutions with repeated use.
  • The antimicrobial activity does not disinfect the instruments; it merely prevents the microorganisms from multiplying.

What is the significance of solutions with enzymatic-activity capabilities?

Which type of solution might be changed fewer times during the day in a high-volume dental office? Why?

A commercial all-purpose ultrasonic cleaner. (Courtesy of Certol.)


Ultrasonic cleaning solutions come in a variety of sizes and types:

Packets (1 oz)


Concentrate solutions

Ready-mixed gallon containers

Which packaging would be most cost-effective in a busy high-volume dental office?

An enzyme ultrasonic cleaner in tablet form. (Courtesy of Crosstex.)


Besides cleaning blood and tissue debris from dental instruments, the ultrasonic cleaner can be used to remove other dental materials from instruments or trays.

Do all dental instruments and equipment go into the ultrasonic cleaning unit?

  • Do not use other chemicals such as plain disinfectants in the ultrasonic cleaner.
  • Some disinfectants can “fix” the blood and debris on the instruments, making subsequent cleaning more difficult.
  • Specific ultrasonic solutions are available for the removal of difficult materials such as cement, tartar, stains, plaster, and alginate.
  • Refer to the instructions of the ultrasonic unit’s manufacturer regarding the specific solution to be used.
  • The ultrasonic cleaning unit should be labeled with both a chemical label and a biohazard label because it contains a chemical and contaminated instruments.