Principles and Techniques of Instrument Processing and Sterilization Chapter 21

Question 1

Introduction

Answer 1

One of the most important
responsibilities of the dental assistant is
to process contaminated instruments
for reuse
 Instrument processing involves much
more than sterilization
 Sterilization is a process intended to kill
all microorganisms and is the highest
level of microbial destruction

Question 2

Classification of Patient Care
Items

Answer 2

These categories help determine which
sterilization methods best ensure the
safety of dental care workers and
patients
 Categories are based on the risk of
infection associated with their intended
use
 Classifications are used to determine
the minimal type of posttreatment
processing

Question 3

Classification of Instruments.1

Answer 3

Critical instruments
 Items used to penetrate soft tissue or bone
 Greatest risk of transmitting infection and
must be sterilized by heat
 Semicritical instruments
 Touch mucous membranes or nonintact skin
 Lower transmission risk
 Sterilized by heat or receive minimum high-
level disinfection if not heat tolerant

Question 3

Classification of Instruments.2

Answer 3

Noncritical instruments
 Contact only intact skin
 Low risk of infection transmission
 Cleaned and processed with EPA-registered
intermediate- or low-level disinfectant

Question 4

Personal Protective Equipment (PPE)

Answer 4

You must always use PPE when
processing instruments
 This includes utility gloves, mask,
eyewear, and protective clothing

Question 5

Transporting and Processing
Contaminated Patient Care
Items

Answer 5

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

Question 6

Instrument-Processing Area

Answer 6

Should be centrally located in the office
to allow easy access from all patient
care areas
 Dedicated only to instrument processing
 Physically separated from operatories and
laboratory
 Not be part of a common walkway

Question 7

Instrument-Processing Area

Answer 7

Needs good air circulation
 Large enough to accommodate all
equipment and supplies
 The area should not have a door or
windows that open to the outside
because dust may enter the area
 Multiple outlets and proper lighting,
water, and an air line and a vacuum line
for flushing high-speed handpieces

Question 8

Contaminated Area

Answer 8

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
 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 wrapping of instruments before

Question 8

Instrument-Processing Area

Answer 8

A deep sink should have hands-free
control 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

Question 9

Workflow Pattern

Answer 9

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 that read:
 “Contaminated items only”
 “Precleaning area”
 “Cleaned items only”
 “Sterile items only”

Question 10

Preparation and Packaging Area

Answer 10

In this area, cleaned instruments and other dental
supplies should be inspected, assembled into sets
or trays, and wrapped or placed in packages for
sterilization
 The preparation and packaging area should consist of counter
space and storage space for sterilized instruments, fresh
disposable supplies, and prepared trays or instrument
cassettes
 Clean instruments are not sterile and could harbor
pathogens
 Instruments must be packaged and sterilized before they are
used on a patient

Question 11

Precleaning and Packaging
Instruments

Answer 11

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

Question 12

Holding Solution.1

Answer 12

 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

Question 12

Holding Solution.2

Answer 12

The container must have a lid and must
be labeled with:
 A biohazard label (because of the
contaminated instruments)
 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

Question 13

Hand Scrubbing

Answer 13

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

Question 14

More About Ultrasonic
Cleaning Solutions

Answer 14

 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

Question 14

Hand Scrubbing Precautions

Answer 14

 Wear goggle-type eyewear and puncture-
resistant gloves, as well as 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 one’s ability to see the sharp
ends
 Allow instruments to air-dry or carefully pat
them with thick toweling
 Never rub or roll instruments while they are

Question 14

Commercial Cleaners

Answer 14

Ultrasonic cleaning solutions come in a
variety of sizes and types
 Packets (1 oz)
 Tablets
 Concentrate solutions
 Ready-mixed gallon containers

Question 14

Ultrasonic Cleaning

Answer 14

 Used to loosen and remove debris from
instruments
 Also reduces 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
 Keep a set of tongs near the ultrasonic
unit; these can be used to remove

Question 14

Ultrasonic Cleaner

Answer 14

 Works by producing sound waves beyond
the range of human hearing
 Sound waves, which can travel through
metal and glass containers, cause
cavitation (formation of bubbles in liquid)
 Bubbles burst by implosion
 Instruments should be processed in the
ultrasonic cleaner until they are visibly
clean
 Time varies from 5 to 15 minutes,
depending on amount and type of
material on the instruments and the

Question 15

Ultrasonic Cleaning Solutions

Answer 15

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
 Antimicrobial activity does not disinfect
the instruments; it merely prevents the
microorganisms from multiplying

Question 16

Care of the Ultrasonic Cleaner

Answer 16

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

Question 17

Testing the Ultrasonic Cleaner

Answer 17

 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 5×5-inch sheet of
lightweight aluminum foil vertically (like a curtain)
half-submerged in fresh, unused solution
 Run the unit for 20 seconds, then hold foil up to
the light
 Surfaces that were submerged should be evenly
marked with a tiny pebbling effect over the entire
surface
 An area without pebbling of more than ½ inch

Question 18

Automated Washers/Disinfectors

Answer 18

Look and work similar to a household dishwasher  Must be approved by the U.S. Food and Drug Administration  Use a combination of very hot recirculating water and detergents to remove organic material  After washing, 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 an automatic washer/disinfector must be wrapped and sterilized before use on a patient

Question 19

Drying, Lubrication, and Corrosion Control

Answer 19

Instruments and burs made of carbon steel will rust during steam sterilization  Rust inhibitors such as sodium nitrate and commercial products can be used to help reduce rust and corrosion  An alternative to a rust inhibitor is to dry the instrument thoroughly with the use of dry heat or unsaturated chemical vapor sterilization (discussed later), which does not cause rusting

Question 20

Packaging Materials

Answer 20

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  Specific types of packaging material are available for each method of

Question 21

Packaging Instruments

Answer 21

Before sterilization, the instruments should be wrapped or packaged to protect them from becoming contaminated after sterilization  When instruments are sterilized without being packaged, they are exposed to the environment as soon as the sterilizer door is opened  They can be contaminated by aerosols in the air, dust, improper handling, or contact with nonsterile surfaces  Additional advantage to packaging instruments is they can be grouped into

Question 22

Methods of Sterilization

Answer 22

 Sterilization destroys all microbial forms, including bacterial spores  Sterile is an absolute term; there is no “partially sterile” or “almost sterile”  All reusable items (critical and semicritical instruments) that come into contact with the patient’s blood, saliva, or mucous membranes must be heat sterilized  The three most common forms of heat sterilization in the dental office are:  Steam  Chemical vapor  Dry heat

Question 22

Sterilization of Unwrapped Instruments

Answer 22

 An unwrapped cycle (sometimes called flash sterilization) is a method for sterilizing unwrapped patient care items for immediate use  The time for unwrapped sterilization cycles depends on the type of sterilizer and the type of item (i.e., porous or nonporous) to be sterilized  Unwrapped sterilization should be used only under certain conditions

Question 23

Steam Autoclave Operation Cycles

Answer 23

 Dental office steam sterilizers usually operate in four cycles  Heat-up cycle  Sterilizing cycle  Depressurization cycle  Drying cycle  Different manufacturers provide different features  Some have added a pre-sterilization vacuum cycle to their units to remove any air pockets from the chamber before steam enters the chamber

Question 24

Steam Autoclave Sterilization

Answer 24

An 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 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

Question 25

Packaging Instruments for Steam Autoclave Sterilization

Answer 25

 Packaging material must be porous enough to permit 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

Question 26

Flash Sterilization

Answer 26

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  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

Question 27

Unsaturated Chemical Vapor Sterilization

Answer 27

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 Safety Data Sheet (SDS) on the chemical vapor solution because of the chemicals’ toxicity

Question 28

Filtration and Monitoring of Chemical Vapors

Answer 28

Newer sterilizers are equipped with a special filtration device that further reduces the amount of chemical vapor remaining in the chamber at the end of the cycle  Older models can usually be retrofitted  Formaldehyde monitoring badges, similar to radiation monitoring devices, are available for employees

Question 28

Advantages of Unsaturated Chemical Vapor Sterilization

Answer 28

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

Question 29

Disadvantages of Chemical Vapor Sterilization

Answer 29

The primary disadvantage is that adequate ventilation 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

Question 30

Pressure, Temperature, and Time

Answer 30

 The three major factors in chemical vapor sterilization are:  Pressure, which should measure 20 psi  Temperature, which should measure 131º C (270º F)  Time, which should measure 20 to 40 minutes

Question 31

Packaging for Unsaturated Chemical Vapor Sterilization

Answer 31

 Standard packaging for chemical vapor sterilization includes:  Film pouches or paper bags  Nylon see-through tubing  Sterilization wrap  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 do under pressure  As with autoclaving, closed containers (e.g., solid- metal trays, capped glass vials) and aluminum foil cannot be used in a chemical vapor sterilizer because they prevent sterilizing agent from reaching instrument inside

Question 32

Dry Heat Sterilization

Answer 32

Operates by heating 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 160º C to 190º C (320º F to 375º F), depending on the type of sterilizer  Advantage of dry heat: Instruments will not rust if they are thoroughly dry before being placed in the sterilizer  Two types: Static air and forced air

Question 33

Static Air Sterilizers

Answer 33

Similar to an oven  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 include amount of time it takes and errors due to incorrect processing time  The wrapping material must be heat resistant

Question 34

Forced Air Sterilizers

Answer 34

Also called rapid heat transfer sterilizers  Circulate 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

Question 35

Ethylene Oxide Sterilization

Answer 35

The use of ethylene oxide gas is a recognized method of sterilization  Carried out at low temperatures, which is an advantage for plastic and rubber items that would melt in heat sterilizers  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  Ineffective on wet items  Toxicity is possible if gas is not handled properly

Question 36

Liquid Chemical Sterilants

Answer 36

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  Glutaraldehyde requires 10 hours of contact time; anything less than 10 hours is disinfection, not sterilization  Be sure you have an MSDS for these products

Question 36

Sterilization Failures

Answer 36

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

Question 37

Sterilization Monitoring

Answer 37

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  Biologic

Question 37

Physical Monitoring

Answer 37

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

Question 38

Process Indicators

Answer 38

 Process indicators (external) are placed outside the instrument packages before sterilization  Examples: 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 that have

Question 38

Chemical Monitoring

Answer 38

Involves the use of a heat-sensitive chemical that changes color when exposed to certain conditions  There are two types of chemical indicators  Process indicators  Process integrators

Question 39

Process Integrators

Answer 39

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  Examples: Strips, tabs, or tubes of colored liquid  The advantage of placing integrators inside each package is that penetration of the packaging by the sterilizing agent is ensured

Question 40

Limitations of Process Integrators

Answer 40

Process indicators and integrators provide immediate visual control of sterilizing conditions  They do not indicate sterility and are not a replacement for biologic monitoring

Question 41

Handpiece Sterilization

Answer 41

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  Dental handpieces must be properly cleaned and heat-sterilized

Question 41

Biologic Monitoring

Answer 41

Biologic monitoring (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

Question 42

Biologic Indicators (BIs)

Answer 42

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 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

Question 43

Handpiece Flushing Techniques

Answer 43

 Flushing the handpiece is the best way to remove debris from the head  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

Question 44

Handpiece Sterilizing Techniques

Answer 44

 Only steam sterilization and chemical vapor sterilizers are recommended because sterilization temperatures should not exceed 275º F (135º C)  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  If handpieces need to be cooled quickly after sterilization, use an air fan to blow room- temperature air over them