Cleaning involves the physical removal of organic
matter to reduce microbial growth prior to the reduction and/or
destruction of microbes through the sterilization or disinfection
process. Organic matter may interfere with the action of antiseptics,
disinfectants and sterilants by preventing adequate penetration.
Soap and water with friction is the standard. Cleaning is
the basic first step in all decontamination processes.
Sterilization involves the removal or destruction
of all microorganisms and their spores.
Disinfection involves the reduction in number
and type of microorganisms -
- High-level includes pasteurization or use of gluteraldehyde.
All life is destroyed except spores. Items that touch mucous
membranes should receive high-level disinfection i.e. flexible
endoscopes, laryngoscopes and other similar instruments.
- Intermediate level hospital-grade disinfectant
- an Environmental Protection Agency (EPA) approved Tuberculocidal
cleaner/disinfectant. Items that touch mucous membranes
or skin that is not intact should receive intermediate-
level disinfection i.e. thermometers, hydrotherapy tanks.
- Low-level sanitizers reduce bacteria to what is
considered a "safe level". Items that touch intact skin
should receive low - level disinfection i.e. stethoscopes,
beds, whirlpools, and equipment which are non-invasive to
Antisepsis is the inhibition of microorganism's
growth on living tissue such as skin preparation before vascular
line insertion or other invasive procedure. Alcohol, chlorhexidine,
and Iodophors, i.e., betadine are most frequently used solution
for antisepsis. Germicidal chemicals used for antisepsis are
not generally adequate for decontaminating environmental surfaces.
There are three categories of patient-care items depending
on their intended use and the potential risk of disease transmission.
Critical items penetrate soft tissue or contact bone,
the bloodstream, or other normally sterile tissues of the
mouth. They have the highest risk of transmitting infection
and should be heat-sterilized between patient uses. Alternatively,
use sterile, single-use disposable devices. Examples include
surgical instruments, periodontal scalers, periodontal probes,
scalpel blades and surgical dental burs.
Semi-critical items contact only mucous membranes
and do not penetrate soft tissues. As such, they have a lower
risk of transmission. Examples of these are mirrors, amalgam
condensers, impression trays and x-ray aiming devices,
Because most items in this category are heat-tolerant, they
should be heat sterilized between patient uses. For heat-sensitive
instruments, high-level disinfection is appropriate.
Dental handpieces are a special case. Even though they do
not penetrate soft tissue, it is difficult for chemical germicides
to reach the internal parts of handpieces. For this reason,
they should be heat sterilized using a steam autoclave or
chemical vapor sterilizer.
Noncritical instruments and devices only contact intact
skin, which serves as an effective barrier to microorganisms.
These items carry such a low risk of transmitting infections
that they usually require only cleaning and low-level disinfection.
If using a low-level disinfectant, according to OSHA, it must
have a label claim for killing HIV and HBV. However, if an
item is visibly bloody, it should be cleaned and disinfected
using an intermediate-level disinfectant before use on another
patient. Examples of instruments in this category include
X-ray head/cones, facebows, pulse oximeters, and blood pressure
Instrument Processing Area
Most instrument cleaning, disinfecting, and sterilization
should occur in a designated central processing area to control
both quality and personnel safety.
To prevent cross-contamination, the instrument processing
area should be physically or spatially divided into regions
for cleaning, packaging, sterilization, and storage.
- In the cleaning area, reusable contaminated instruments
are received, sorted, and cleaned.
- The packaging area is for inspecting, assembling, and
packaging clean instruments in preparation for final sterilization.
- The sterilization and storage area contains the sterilizers
and related supplies, incubators for analyzing spore tests
(if performed in office-although some states require using
a testing service), and can contain enclosed storage for
sterile items and disposable (single-use) items.
As noted above in the definitions, cleaning is the first
step in a decontamination process.
Automated or mechanical cleaning equipment, such as
ultrasonic cleaners, instrument washers, and washer-disinfectors,
are commonly used to clean dental instruments. Automated cleaners
increase the efficiency of the cleaning process and reduce
the handling of sharp instruments. After cleaning, instruments
should be rinsed with water to remove chemical or detergent
If manual cleaning is necessary, soak instruments
in a rigid container filled with detergent, disinfectant/detergent,
or an enzymatic cleaner. This step prevents drying of patient
material and makes cleaning easier and less time consuming.
- Do not use high-level disinfectants/sterilants (e.g.,
glutaraldehyde) as instrument-holding solutions.
- To avoid injury from sharp instruments, personnel should
wear puncture-resistant, heavy-duty, utility gloves (i.e.,
not patient care gloves) when handling or manually cleaning
contaminated instruments and devices. To protect against
splashes, a facemask, eye protection or face shield, and
a gown or jacket should be worn.
Preparation and Packaging
After thorough cleaning and drying of instruments, critical
and semi-critical instruments that will be stored before use
should be wrapped or placed into container systems prior to
heat sterilization. This step protects items from contamination
after the sterilization cycle and during storage.
Open or unlock hinged instruments so that all surfaces are
Place a chemical indicator inside each wrapped package. If
the indicator cannot be seen from the outside, place another
indicator (e.g., indicator tape) on the outside of the package.
Always wear heavy-duty, puncture-resistant utility gloves
while inspecting and packaging instruments.
There are three types of heat sterilization methods commonly
used in dentistry.
- Steam under pressure (autoclaving). There are
two types of tabletop steam autoclaves: o In most commonly
used gravity displacement sterilizers, steam enters the
chamber and unsaturated air is forced out of the chamber
through a vent in the chamber wall. o In contrast, pre-vacuum
sterilizers are fitted with a vacuum pump to create a vacuum
in the chamber and ensure air removal from the sterilizing
chamber and load before the chamber is pressurized
with steam. This method improves the speed and efficiency
of the sterilization process.
- Dry heat sterilizers are either static air (convection
or FDA-approved oven type) or forced air (rapid heat-transfer).
- Unsaturated chemical vapor sterilizers use a proprietary
formula of alcohol/formaldehyde.
With all of these methods, always use FDA-approved devices
and closely follow the manufacturer's instructions for proper
Liquid Chemical Sterilant/Disinfectant
Heat-sensitive instruments can be sterilized or high-level
disinfected by soaking them in a liquid chemical germicide
cleared by the FDA. However, exposure to these powerful and
toxic chemicals can be harmful to DHCP and patients if the
manufacturer's instructions for use and safety precautions
are not followed precisely. For these reasons, CDC encourages
the use of heat-tolerant or disposable alternatives.
Sterilization Monitoring - Types
Proper monitoring of sterilization procedures should include
a combination of process indicators, including the following:
- Mechanical-involves assessment of cycle time,
temperature, and pressure by observing the gauges or displays
on the sterilizer.
- Chemical-uses sensitive chemicals that change
color when a given parameter is reached (e.g., heat-sensitive
external tape, internal chemical indicator strip).
- Biological-this method is the most valid method
for monitoring the sterilization process because it assesses
the process directly. It does so by using the most heat-resistant
microorganisms and not by using indicators that only test
the physical and chemical conditions necessary for sterilization.
Mechanical and chemical indicators should be assessed with
each load. If either mechanical indicators or internal or
external chemical indicators indicate inadequate processing,
items in the load should not be used until reprocessed.
Biological indicators should be assessed at least once a
Storage of Sterile and Clean Items
DHCP have a choice about how they maintain their instrument
storage area - either date- or event-related shelf-life practices.
In date-related packing, every sterilized package is expiration-dated
and the instruments are used on a "first in, first out" basis.
In event-related practice, the contents of a sterilized package
should remain sterile indefinitely unless some event, for
example, torn or wet packaging material, causes it to become
potentially contaminated. It is still useful to place the
date of sterilization and identify the sterilizer used if
multiple sterilizers are utilized in the office. In case of
sterilization failure, this information would facilitate retrieval
of processed items.
- Examine each package. If it is damaged in any way, items
should be re-cleaned, re-wrapped, and re-sterilized. Even
if an event-related approach is used, all packages should
be labeled with the date of sterilization and which sterilizer
was used, should a sterilization failure occur.
- Store all sterile and clean items and supplies in dry,
closed, or covered cabinets.
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