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ental ssessment
October 2010
Dental Sterilization Solutions
y Avi Cohen – Head of Medical Solutions, Objet Geometries Ltd
Abstract •
hemical sterilization
This whitepaper describes the different sterilization • adiation sterilization
methods and technologies currently available in
today’s dental equipment sterilization market with Common High Temperature Sterilization
observation to apid rototype models ocus is A. Steam Autoclave
given to the more common sterilization methods team autoclave is the oldest safest and most
used or available for dental equipment in hospitals cost effective method of sterilization in the medical
and clinics today t the end of the paper there equipment industry The steam reaches 1211°
is a conclusion and table which summarizes the 2000° in the pressure chamber at 1 The
common sterilization methods i sterilization sterilization period is dependent on the temperature
methodsproducts were isolated and ranked and size of load and can range from 100 minutes
based on their sterile efficacy and applicability to
medical instruments and apid prototype models
onfigurable cycles allow the user to customize
the sterilization cycle for items such as hard items
terilization means the use of a physical or chemical wrapped items liquids in vented containers waste
procedure to destroy all microbial life including highly and glassware
resistant bacterial spores The fastest steam sterilization used is flash sterilization
acterial spores are the most resistant of all living and it can be accomplished using either gravity
organisms because their capability to withstand displacement or prevacuum cycles t is generally
destructive agents lthough the chemical or physical a highspeed steam sterilization of an unwrapped
process used to destroy all pathogenic microorganisms instrument or device for to 10 minutes in 12°
including spores is not absolute when all parameters saturated steam
of the sterilization process have been met instruments This type of sterilization is only intended for use
supplies and equipment are thought to be sterile in hospital operating rooms for urgently needed
equipment
n obect should be sterilized depending on its intended
use
ritical obects those that enter sterile tissues or the n the steam autoclave process microorganisms are
vascular system or through which blood flows such as killed by heat and this is accelerated by the addition of
implanted medical devices require sterilization before moisture team by itself is not sufficient for sterilization
atmospheric is needed
use and pressure that is greater than
tems that touch mucous membranes or no intact skin to increase the temperature of steam for thermal destruction
like endoscopes respiratory therapy equipment of microbial life
and diaphragms require highlevel disinfection Solutions:
which would not be discussed in this whitepaper team autoclave is used mostly for surgical instruments
terilization falls into the following three categories This method is not well suited for heat sensitive materials
• igh temperaturepressure sterilization and instruments
any surgical instruments are not designed to withstand sterilization safest fastest and least epensive and tO
prolonged heat and moisture of the steam sterilization gas sterilization which leaves toic residuals t is a low
process This leads to alternative sterilization categories temperature nontoic but fairly epensive sterilization
chemical sterilization and radiation sterilization which method n this process hydrogen peroide is activated
allow heat and moisture sensitive materials to be sterilized to create a reactive plasma or vapor
The terrad system is a ydrogen eroide as lasma
Common Chemical Sterilization terilization system with an operating temperature range
A. Ethylene Oxie EtO as of 0°
Operating cycle times range from 0
minutes depending on size of system
thylene Oide gas was introduced in the 10’s and This sterilization system uses a combination of hydrogen
it is an effective low temperature chemical sterilization peroide and low temperature gas plasma to quickly
method t also takes longer than steam sterilization sterilize most medical instruments and materials without
typically 11 hours for a complete cycle Temperatures leaving any toic residues terilization by this method
reached during sterilization are usually in the 00°
occurs in a low moisture environment
range The ydrogen eroide lasma rocess using terrad
thylene oide tO is a chemical agent that kills The process consists of two consecutive and equal
microorganisms including spores tO gas must have sterilization phases
direct contact with microorganisms on the items to be
sterilized ue to tO being highly flammable and ¡acuum replasma tage
eplosive in air it must be used in an eplosionproof • ¢hen a low pressure is achieved in the vacuum stage
sterilizing chamber in a controlled environment low temperature air plasma is generated This helps in
tems sterilized by this process must be packaged with removing residual moisture from the chamber The system
wraps and be aerated The aeration time may be long is then vented to atmospheric pressure at the end of this
and is needed to make sterilized items safe for handling stage
and patient use terilization tage
• ressure in chamber is reduced and an aqueous
n general tO gas is a reliable and safe agent for solution of hydrogen peroide is inected and vaporized
sterilization when handled properly into chamber
Solutions: • The hydrogen peroide diffuses throughout the
chamber surrounds the items to be sterilized and starts
tO is used to sterilize items that are heat or moisture the inactivation of the microorganisms
sensitive isadvantages of tO gas are that it can leave • fter the pressure is reduced applying radio frequency
toic residues on sterilized items and it possesses several energy creates an electric field and thus forms low
physical and health hazards to personnel and patients that temperature plasma
merit special attention • ree radicals are generated in the plasma by breaking
ince tO poses several health hazards there are apart the hydrogen peroide vapor Once the activated
currently two alternative technologies that are currently components react with the organisms
available terrad a plasma phase hydrogen peroide and kill them they lose their high energy and recombine
based sterilizing agent and teris a per acetic acid based to form oygen water vapor and nontoic byproducts
technology
• This is half of the total sterilization process The other
half of the cycle is completed by repeating the above
. Sterra o Temperature Hyrogen eroxie sterilization steps
lasma • t the completion of the second half cycle the source
ow temperature plasma sterilization was introduced to of energy is turned off vacuum is released and
fill the gap between autoclave high temperature steam chamber is returned back to atmospheric pressure by
introduction of filtered air toicity concerns
olutions
This system is best suited to sterilize heat sensitive medical Solutions:
equipment such as endoscopic equipment ¢ith two This solution is frequently used on surgical cameras
systems terrad provides sterilization solutions for both endoscopes The item to be disinfected must be
smaller and larger olutions thoroughly cleaned and dried before immersion fter
immersion the item must be rinsed thoroughly with sterile
C. Steris System Sterile rocessing System water prior to use
The teris ystem is another more common low .. Common
aiation Sterilization
temperature sterile processing system t uses the teris A. amma eta Sterilization
20 terilant
oncentrate that combines peracetic acid a rradiation is an effective sterilization method but it
chemical biocidal agent and a proprietary anticorrosion is limited to commercial use only The product to be
formulation to kill microorganisms at low temperature The sterilized is eposed to radiation for 10 to 20 hours
process is achieved at a temperature of depending on the strength of the source The highest
0°
temperatures reached in gamma sterilization are usually
The teris 20 terilant
oncentrate is mied with sterile 00°
amma radiation is popular for sterilizing
water to create the solution that flows into the sterilization before shipment and it can be done through the
chamber The sterilization time is 12 minutes packaging
This is followed by repetitive sterile water rinses to
complete the process The entire process is completed in The principal sources of ionizing radiation are beta
less than 0 minutes for a standard cycle particles and gamma rays
eracetic acid by itself is an oidant and disinfecting eta particles free electrons are transmitted through a
agent for liquid immersion highvoltage electron beam from a linear accelerator
These highenergy free electrons will penetrate into matter
t maintains its effectiveness when high levels of organic before being stopped by collisions with other atoms This
debris are present t is an acetic acid plus an etra means their usefulness in sterilizing an obect is limited by
oygen atom that reacts with most cellular components to the density thickness of the obect
destroy cells and by the energy of the electrons These free electrons
produce their effect by ionizing the atoms they hit
Solutions: producing secondary electrons that kill microorganisms
Only immersible instruments can be used with this method
obalt 0 is a radioactive isotope capable of breaking
and only a few instruments can be sterilized at one time down to produce gamma rays amma rays are
£o packaging required electromagnetic waves that have the ability to penetrate
a much greater distance than beta rays before losing
ide O olution – lternative to lutaraldehyde their energy from collision ecause they travel with
ide® O olution is a igh evel isinfectant the speed of light they must pass through a thickness
for use in reprocessing heat sensitive medical devices measuring several feet before making sufficient collisions
ide O olution provides highlevel disinfection in 12 to lose all of their energy
minutes at room temperature 20o
and is particularly
active against mycobacteria olutions
¥ O olution has the broad materials compatibility The radiation can change the properties of some
of glutaraldehyde requires no activation and has minimal materials like plastics and have adverse affects on glues
odor The
ide O or adhesives
olution is replacing
ide and
ide lus due to their
s you can see each of the si common methods ¡ eries
discussed above have their advantages and ¡ ¡aporized ydrogen eroide eries
disadvantages terilization ystem for edical evices is yet another
low temperature sterilization system t is different from
Other terilization ethods the terrad system in that it only uses hydrogen peroide
n this section the other less common sterilization methods in vaporized form for sterilization while the terrad
are described These methods are either eisting being system uses
replaced by new sterilization or are still in development vaporized hydrogen peroide to initiate the sterilization
1 Other igh Temperature terilization and then plasma to complete the sterilization process
ry eat n the ¡ process hydrogen peroide vapor is inected
into the chamber via a series of pulses to sterilize
This process is conducted at 1010°
for a minimum of packaged medical and diagnostic devices The cycle
two hours ue to its high temperatures its applicable use time is 2 hours and the operating temperature ranges
is limited from 00°
ry heat in the form of hot air is used primarily to sterilize £ote This system is large capital equipment that uses
anhydrous oils petroleum products and bulk powders hydrogen peroide On the other hand
that steam and ethylene oide gas cannot penetrate n teris
orporation’s other product the teris ystem 1 is
the absence of moisture higher temperatures are required a portable tabletop system that
than when moisture is present because microorganisms uses peracetic acid as the sterilant and it is used to
are destroyed through a very slow process of heat sterilize equipment right before use
absorption by conduction
2 Other
hemical terilization
hlorine ioide
lutaraldehyde
ide lus¦ and
ide¦
hlorine ioide is a chemical liquid sterilization
•
ide lus olution is a disinfectant that is used to process The best operating temperature range for this
disinfect medical instruments process is 20°
while using low concentrations of
lO2 The process requires hours of contact time to
t is a § alkaline glutaraldehyde solution which has achieve sterilization The presence of organic matter
tuberculocidal and highlevel disinfection capabilities t reduces activity processor converts a compound of
achieves highlevel disinfection in 20 minutes at dilute chlorine gas with sodium chlorite to form
lO2
2°
and has up to a 2day reuse life gas and this gas is then eposed to the equipment in a
•
ide ctivated ialdehyde olution is used to disinfect sterilizing chamber
medical instruments and endoscopes This solution can Ozone
also be used in an automated reprocessor glutaraldehyde Ozone sterilizes by oidation a process that destroys
solution which has tuberculocidal and highlevel organic and inorganic matter t penetrates membrane
disinfection capabilities t achieves highlevel disinfection of cells causing them to eplode n this process a
in minutes at 2°
and has up to a 1day reuse life generator is used to convert oygen to ozone as a
oth have been used as a cold liquid highlevel to 12 percent concentration of ozone continuously
disinfectant for heat sensitive equipment flows through the chamber Ozone penetration is
£ote
ide glutaraldehyde products are being controlled by vacuum pressure or by adding humidity
withdrawn from the uropean market due to concerns fter the process is complete oygen is allowed to
that it is toic and harmful to health care staff in hospitals flow through the chamber to purge the ozone The
lso the ¨ market is requiring glutaraldehydefree cycle time may be up to 0 minutes depending on the
chemical solutions which led to the formulation of the size of the chamber or load of items to be sterilized
ide O solution ue to ozone gas being corrosive and it being able to
damage moisture sensitive equipment or models there
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