Chapter 21, Unit 4, Principles and Techniques of Instrument Processing and Sterilization

Instrument processing

•Instrument processing involves much more than sterilization. Proper processing of contaminated dental instruments is actually a seven-step process. •Although the seven steps are not difficult to learn, it is very important for you to have a clear understanding of how and why each step is performed.

Steam autoclave

-is used to sterilize dental instruments and other items by means of steam under pressure. •Steam sterilization involves heating water to generate steam, producing a moist heat that rapidly kills microorganisms. •As the steam fills the sterilizing chamber, the cooler air is pushed from an escape valve, which then closes and allows the pressure to increase. •It is actually the heat, not the pressure, that kills the microorganisms. •Packaging material for steam sterilization must be porous enough to permit the steam to penetrate to the instruments inside. •The packaging material may be fabric but most often is sealed film or paper pouches, nylon tubing, sterilizing wrap, or paper-wrapped cassettes. •One disadvantage of steam sterilization is that the moisture may cause corrosion on some high-carbon steel instruments. •Distilled water should be used in autoclaves instead of tap water, which often contains minerals and impurities. Distilled water helps minimize corrosion and pitting.

Dry-heat sterilization

-operates by heating up air and transferring that heat from the air to the instruments. •This form of sterilization requires higher temperatures than does steam or chemical-vapor sterilization. •Dry-heat sterilizers operate at approximately 160° to 190° C (320°-375° F), depending on the type of sterilizer. •The advantage of dry heat is that the instruments will not rust if they are thoroughly dry before being placed in the sterilizer. •There are two types of dry-heat sterilizers: static-air and forced-air.

Instrument processing area

-the date that you sterilized it -what's in it -your initials

Semicritical instruments

-touch mucous membranes or nonintact skin and have a lower risk of disease transmission. •The majority of semicritical items in dentistry are heat-tolerant, and they should also be sterilized. •If the item will be damaged by heat, it should undergo, at a minimum, high-level disinfection.

-steam -chemical vapor -dry heat

3 most common forms of heat sterilization in the delta office are:

Forced-air sterilizer

-also called the rapid-heat-transfer sterilizer, circulates the hot air throughout the chamber at a high velocity. •This action permits rapid transfer of heat energy from the air to the instruments, reducing the time needed for sterilization. •Exposure time in a forced-air sterilizer, after the sterilizing temperature has been reached, ranges from 6 minutes for unpackaged items to 12 minutes for packaged items.

Critical instruments

-are items used to penetrate soft tissue or bone. •They have the greatest risk of transmitting infection and should be sterilized with the use of heat. •Examples of critical instruments include forceps, scalpels, bone chisels, scalers, and burs.

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.

Ethylene oxide sterilization

-is a recognized method of sterilization. This method is carried out at low temperatures, which is an advantage for plastic and rubber items that would melt in heat sterilizers. •However, ethylene oxide sterilization requires 4 to 12 hours, depending on the sterilizer model, and at least 16 hours of poststerilization aeration is required to remove the gas molecules bound to plastic and rubber surfaces. •Ethylene oxide is ineffective on wet items. Toxicity is possible if the gas is not handled properly. •Ethylene oxide sterilizing units are often used in large clinics or hospital settings but are only rarely found in private dental practices.

Disadvantages of chemical-vapor sterilization

-is essential because residual chemical vapors containing formaldehyde and methyl alcohol may be released when the chamber door is opened at the end of the cycle. •These vapors can temporarily leave an unpleasant odor in the area and may be irritating to the eyes.

Static-air sterilizer

-is similar to an oven: The heating coils are on the bottom of the chamber, and the hot air rises inside by way of natural convection. •Heat is transferred from the static (nonmoving) air to the instruments in 1 to 2 hours. •Disadvantages of static dry heat: The sterilization process is time-consuming, and it may not be effective if the operator errs in calculating the correct processing time. •The wrapping material must be heat-resistant. Aluminum foil, metal, and glass containers may be used. Paper and cloth packs should be avoided because they may burn or discolor in the intense heat.

Chemical-vapor sterilization

-is similar to autoclaving, except that a combination of chemicals (alcohol, formaldehyde, ketone, acetone, and water) is used instead of water to create a vapor for sterilization. •OSHA requires a material-safety data sheet, or MSDS, on the chemical-vapor solution because of the chemicals' toxicity.

Hand scrubbing

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

Biologic monitoring

-or spore testing, is the only way to determine whether sterilization has occurred and all bacteria and endospores have been killed. •The CDC, American Dental Association, and Office of Safety and Asepsis Procedures Research Foundation recommend at least weekly biologic testing of sterilization equipment. •Several states also require routine biologic checks at weekly, monthly, or cycle-specific intervals, such as spore testing every 40 hours of use or every 30 days.

Noncritical instruments

-pose the least risk of transmission of infection because they come into contact only with intact skin, which is an effective barrier to microorganisms. •These items should be cleaned and processed with the use of an EPA-registered intermediate-level or low-level disinfectant after each patient use. •Noncritical clinical devices include the position indicator device of the x-ray unit tube head, the lead apron, and the curing light that comes into contact only with intact skin.

Instrument-processing area (sterilization area)

-should be centrally located in the office to permit easy access from all patient-care areas. •A central location minimizes the need to carry contaminated items through clean areas of the office (where sterilized instruments, fresh disposable supplies, and prepared trays are stored).

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.

•Heat-up •Sterilization •Depressurization •Drying

Dental-office steam sterilizers usually operates in four cycles:

Seven step process- -1. Transport- transport contaminated instruments to the processing area in a manner that minimizes the risk of exposure to persons and the environment. Use appropriate PPE and a rigid, leakproof container -2. Cleaning- clean instruments with a hands-free, mechanical process such as use of an ultrasonic cleaner or instrument washer. If instruments cannot be cleaned immediately, use a holding solution -3. Packaging- in the clean area, wrap / package instruments. If an indicator is not visible on the outside of the package, place an external process indicator on the package -4. Sterilization- load the sterilizer according to the manufacturer's instructions. Label packages. Do not overload the sterilizer. Place packages on their edges in single layers or on racks to increase circulation of the sterilizing agent around the instruments. Operate the sterilizer according o the manufacturer's instructions. Allow packages to cool before removing them from the sterilizer. Allow packages to cool before handling. -5. Storage- store instruments in a clean, dry environment in a manner that maintains the integrity of the package. Rotate packages so that those with the oldest sterilization dates will be used first -6. Delivery- deliver packages to point of use in manner that maintains sterility of the instruments until they are used. Inspect each package for damage. Open package aseptically. -7. Quality- an effective quality assurance program should incorporate training, record keeping, maintenance, and the use of biological indicators

How many steps are there in instrument processing?

Intermediate-level disinfection

Inactivates Mycobacterium tuberculosis and destroys less-resistant organisms such as hepatitis B virus and human immunodeficiency virus

Low-level disinfection

Ineffective against M. Tuberculosis and should be used only in the dental office for house-keeping purposes

•Critical •Semicritical •Noncritical

Patient-care items are categorized into three classifications:

Sterilization

Process that inactivates all microbial life, including bacterial spores, viruses, bacteria, and fungi

Disinfection

Process that kills disease-causing microorganisms, but not necessarily all microbial life

High-level disinfection

Process that kills some but not all endospores and inactivates Mycobacterium tuberculosis

Precleaning

Reducing the number of microorganisms that are present by physically removing debris

•Sterilization may fail when direct contact for the correct time between the sterilizing agent (chemical or steam) and all surfaces of the items being processed is insufficient. •Several factors can cause the sterilization process to fail, including improper instrument cleaning or packaging and sterilizer malfunction.

Sterilization failures?

•Pressure, which should measure 20 psi •Temperature, which should measure 131° C (270° F) •Time, which should measure 20 to 40 minutes

Three major factor in chemical-vapor sterilization are:

-process indicators -process integrators

Two types of indicators?

Chemical monitoring (external and internal)

involves the use of a heat-sensitive chemical that changes color when exposed to certain conditions.

Instrument-processing area

•A deep sink should have hands-free controls for instrument rinsing and (if space permits) a foot-operated or other hands-free trash receptacle. •The flooring should be an uncarpeted, seamless, hard surface. •The size, shape, and accessories of the instrument- processing area vary among dental offices.

Contaminated area

•All soiled instruments are brought into the ________ _______, 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.

Biologic indicators

•Also known as spore tests, biologic indicators (BIs) are vials or strips of paper that contain harmless bacterial spores (which are highly resistant to heat). •Three BIs are used in testing. Two BIs are placed inside instrument packs, and the sterilizer is operated under normal conditions. The third strip is set aside as a control. •After the load has been sterilized, all BIs are cultured. If the spores survive the sterilization cycle (a positive culture), sterilization failure has occurred. •If the spores are killed (a negative culture), the sterilization cycle was successful. •The culturing of the spore test is usually handled with the use of a mail-in monitoring service.

Handpiece flushing Techniques

•Flushing the handpiece is the best way to remove debris from the head of the handpiece. •To flush a dental handpiece: •Attach a pressurized handpiece cleaner to the intake tube of the handpiece (where the air passes through). •Flush the head of the handpiece to remove debris. •Blow out the handpiece using compressed air to remove debris before sterilization. •Running coolant water from the dental unit through the handpiece at chairside is insufficient. Coolant water does not run through the turbine chamber, where debris can collect.

Personal Protective Equipment

•For disease agents from a previous patient to be prevented from being transferred to yourself, another dental-team member, or the next patient, instrument processing must be performed in a consistent and disciplined manner. •You must always use personal protective equipment (PPE), including utility gloves, mask, eyewear, and protective clothing, when processing instruments.

Handpiece sterilization

•High-speed dental handpieces rotate at speeds up to 400,000 revolutions per minute (rpm). •Blood, saliva, and tooth fragments, as well as restorative materials, may lodge in the head of the handpiece, where they may be retained and transferred to another patient. •Therefore, dental handpieces must be properly cleaned and heat-sterilized.

Testing the ultrasonic cleaner

•If you notice that the instruments are not being cleaned completely with processing in the ultrasonic cleaner, the unit may not be functioning properly. •To determine whether the ultrasonic cleaner is working properly, hold a 5-by-5-inch sheet of lightweight aluminum foil vertically (like a curtain) half-submerged in fresh, unused solution. •Run the unit for 20 seconds, then hold the foil up to the light. •The surfaces that were submerged in the solution should be evenly marked with a tiny pebbling effect over the entire surface. •An area without pebbling of more than ½ inch indicates a problem with the unit, and it needs to be serviced by the manufacturer.

Precleaning and packaging instruments

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

Sterilization monitoring

•It is critical that dental instruments be properly sterilized. •Because microorganisms cannot be seen with the naked eye, the major difficulty in sterilization is determining when an item is sterile. •Currently, three forms of sterilization monitoring are used: physical, chemical, and biologic. •All three processes are unique, have different functions, and must be used consistently to ensure sterility.

Chemical-liquid sterilization

•Not all items can withstand heat sterilization. Some types of plastics, such as some rubber dam frames, shade guides, and x-ray film-holding devices, are damaged by heat sterilization. •A liquid sterilant such as 2.0% to 3.4% glutaraldehyde must be used for sterilization of these items. •Sterilization in glutaraldehyde requires 10 hours of contact time; anything less than 10 hours is disinfection, not sterilization. •Be sure that you have an MSDS for these products. All employees should be properly trained to handle them.

Handpiece sterilization techniques

•Only steam sterilization and chemical vapor sterilizers are recommended, because handpiece sterilization temperatures should not exceed 275° F (135° C). •Unless they will be used immediately after sterilization, handpieces should be packaged in bags, wraps, or packs to protect them from contamination before use. •Never run a handpiece "hot" out of the sterilizer, and avoid rapid cool-downs, such as running the handpiece under cold water. Handpieces use very small metal components; extreme cold changes stresses the metal. •If handpieces need to be cooled quickly after sterilization, use an air fan to blow room-temperature air over them.

Physical monitoring

•Physical monitoring of the sterilization process involves looking at the gauges and readings on the sterilizer and recording temperatures, pressure, and exposure time. •Although correct readings do not guarantee sterilization, an incorrect reading is the first signal of a problem. •Remember that the reading reflects the temperature in the chamber, not inside the pack. •For this reason, problems with overloading or improper packaging would not be revealed by the reading on the gauges.

Process indicators

•Process indicators (external) are placed outside the instrument packages before sterilization. •Examples include autoclave tape and color-change markings on packages or bags. •Process indicators simply identify instrument packs that have been exposed to a certain temperature; they do not indicate duration or pressure. •Process indicators are useful in distinguishing between packages that have been processed and those have not.

Process integrators

•Process integrators (internal) are placed inside instrument packages. •They respond to a combination of pressure, temperature, and time. •Process integrators are also known as multiparameter indicators. All sterilization factors are integrated. •Process indicators and integrators provide immediate visual control of sterilizing conditions. •They do not indicate sterility and are not a replacement for biologic monitoring.

Workflow pattern

•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"

Flash sterilization

•Rapid or "flash" sterilization of dental instruments is accomplished by means of rapid heat transfer, steam, and unsaturated chemical vapor. •Flash sterilization may be used only on instruments that are placed in the chamber unwrapped. This involves a compromise, because the sterility of the instruments is immediately defeated when the instruments are removed from the sterilizer. •Flash sterilization should also be used only for instruments that are to be promptly used on removal from the sterilizer. •It is always the best policy to use a method of sterilization in which the instruments can be packaged before use and remain packaged until the time of use.

Packaging for chemical-vapor sterilization

•Standard packaging for chemical-vapor sterilization includes film pouches or paper bags, nylon see-through tubing, sterilization wrap, and wrapped cassettes. •Thick or tightly wrapped items require longer exposure because of the inability of the unsaturated chemical vapors to penetrate as well as saturated chemical vapors under pressure do. •As with autoclaving, closed containers (e.g., solid-metal trays and capped glass vials) and aluminum foil cannot be used in a chemical-vapor sterilizer because they prevent the sterilizing agent from reaching the instruments inside.

Packaging materials

•Sterilization packaging materials and cassettes are medical devices and therefore must be FDA-approved. •It is of critical importance to use only products and materials that are labeled as "sterilization" packaging. •Never substitute products such as plastic wraps, paper, or zipper-lock freezer bags that are not registered for this purpose. These products may melt or prevent the sterilizing agent from reaching the instruments inside. •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.

Transporting and Processing Contaminated Patient-Care Items

•The dental assistant may be exposed to microorganisms through contact with contaminated instruments or other patient-care items. •Exposure may occur through percutaneous injury (e.g., needlesticks, cuts) or contact with the mucous membranes of the eyes, nose, or mouth.

Instrument-processing area

•The ideal instrument-processing area: •Should be dedicated only to instrument processing •Should be physically separated from the operatories and dental laboratory •Should not be a part of a common walkway •The area should not have a door or windows that open to the outside, because dust may enter the area. •The processing area should have good air circulation to control the heat generated by the sterilizers. •The size of the area should accommodate all the equipment and supplies necessary for instrument processing, with multiple outlets and proper lighting, water, and air and vacuum lines for flushing of high-speed handpieces.

Advantages of chemical-vapor sterilization

•The major advantage of the chemical-vapor sterilizer is that it does not rust, dull, or corrode dry metal instruments. •The low water content of the vapor prevents destruction of items such as endodontic files, orthodontic pliers, wires, bands, and burs. •A wide range of items can be sterilized routinely without damage. •Other advantages include the short cycle time and the availability of a dry instrument after the cycle.

Care of the ultrasonic cleaner

•The ultrasonic cleaning solution is highly contaminated and must be discarded at least once a day or sooner if it becomes visibly cloudy. •When the solution is being changed, the inside of the pan and lid should be rinsed with water, disinfected, rinsed again, and dried. •All PPE should be worn while solutions are being changed in the ultrasonic cleaner.

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.

Ultra 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. •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.