Principles and Techniques of Instrument Processing and Sterilization Chapter 21 Flashcards
Introduction
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
Classification of Patient Care
Items
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
Classification of Instruments.1
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
Classification of Instruments.2
Noncritical instruments
Contact only intact skin
Low risk of infection transmission
Cleaned and processed with EPA-registered
intermediate- or low-level disinfectant
Personal Protective Equipment (PPE)
You must always use PPE when
processing instruments
This includes utility gloves, mask,
eyewear, and protective clothing
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 can occur through
percutaneous injury (e.g., needle sticks,
cuts) or contact with the mucous
membranes of the eyes, nose, or mouth
Instrument-Processing Area
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
Instrument-Processing Area
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
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
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
Instrument-Processing Area
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
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 that read:
“Contaminated items only”
“Precleaning area”
“Cleaned items only”
“Sterile items only”
Preparation and Packaging Area
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
Precleaning and Packaging
Instruments
Instruments may be precleaned in one
of three ways
Hand scrubbing
Ultrasonic cleaning
Instrument-washing machine
Holding Solution.1
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
Holding Solution.2
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
Hand Scrubbing
Hand scrubbing is the least desirable
method of cleaning instruments
because it requires direct hand contact
with the contaminated instrument
More About Ultrasonic
Cleaning Solutions
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
Hand Scrubbing Precautions
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
Commercial Cleaners
Ultrasonic cleaning solutions come in a
variety of sizes and types
Packets (1 oz)
Tablets
Concentrate solutions
Ready-mixed gallon containers
Ultrasonic Cleaning
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
Ultrasonic Cleaner
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
Ultrasonic Cleaning Solutions
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
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
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 5×5-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
Automated Washers/Disinfectors
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
Drying, Lubrication,
and Corrosion Control
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
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
Specific types of packaging material are
available for each method of
Packaging Instruments
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
Methods of Sterilization
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
Sterilization of Unwrapped
Instruments
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
Steam Autoclave Operation
Cycles
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
Steam Autoclave Sterilization
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
Packaging Instruments for
Steam Autoclave Sterilization
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
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
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
Unsaturated Chemical
Vapor Sterilization
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
Filtration and Monitoring
of Chemical Vapors
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
Advantages of Unsaturated
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
Disadvantages of Chemical
Vapor Sterilization
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
Pressure, Temperature, and Time
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
Packaging for Unsaturated
Chemical Vapor Sterilization
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
Dry Heat Sterilization
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
Static Air Sterilizers
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
Forced Air Sterilizers
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
Ethylene Oxide Sterilization
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
Liquid Chemical Sterilants
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
Sterilization Failures
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 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
Biologic
Physical Monitoring
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
Process Indicators
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
Chemical Monitoring
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
Process Integrators
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
Limitations of Process
Integrators
Process indicators and integrators
provide immediate visual control of
sterilizing conditions
They do not indicate sterility and are
not a replacement for biologic
monitoring
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
Dental handpieces must be properly
cleaned and heat-sterilized
Biologic Monitoring
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
Biologic Indicators (BIs)
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
Handpiece Flushing Techniques
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
Handpiece Sterilizing Techniques
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
