Sterilization in operative dentistry

Sterilization and
Disinfection in
Operative Dentistry
‫د‬.‫الخالدي‬ ‫فرحان‬ ‫عماد‬
‫الموصل‬ ‫جامعه‬ ‫االسنان‬ ‫طب‬ ‫كليه‬
PhD , MSc conservative dentistry
Dr. Emad Farhan Alkhalidi
Collage of dentistry Mosul university
PhD, MSc conservative dentistry

it indicate a procedure which willSterilization:
completely kill all living organisms including
bacteria, vegetative bacteria and viruses in any
given set of condition . sterilization should be
done to prevent the cross infection between
patients there are very dangerous diseases like
viral hepatitis and AIDS transmitted by dental
instruments.
it indicate aprocedure affording aDisinfection:
valuable measure of control of infection, but
definitely inferior to sterilization, in particular
bacterial spores and many vegetative organism
and viruses may not be killed.

Methods of sterilization:
1-Physical methods
2-chemical methods
3- combination between both

Physical methods:
1-boiling water: its economic method, boiling water does
not kill spores and can not sterilize instruments. The
disadvantage of boiling water is rusting of the instrument in
addition to dulling the sharp one. to minimize this
disadvantage can use rust inhibitor such as sodium
bicarbonate.
Boiling is a method of high level disinfection that is useful
when actual sterilization can not be achieved. Well-cleaned
items must be completely submerged and allowed to boil at
100C° for 10-30 minutes this may kill many of
microorganism, but most viruses will not be killed.

Physical methods:
2- Dry heat sterilization:
Hot air oven widely used in dentistry because of its
efficient and economic and instrument are not going to
rust.
Two points should be taken in consideration:
the temperature and the time. The recommended
temperature is 160 C° which should be held of
minimum time of 60 minutes. The time required to
sterilize can be reduced by raising the temperature.
: the highDisadvantages of dry heat method
temperature will affect the sharpness of instruments,
and the process is slow.

Physical methods:
Short-Cycle, High-Temperature Dry Heat Ovens:
A rapid high-temperature process that uses a forced-
draft oven (a mechanical convection oven that
circulates air with a fan or blower) It reduces total
sterilization time to 6 minutes for unwrapped and 12
minutes for wrapped instruments these short-cycle
high temperature dry heat ovens operate at
approximately370° to 375° F. (185C°)

Physical methods:
3- Pressure steam sterilization “autoclaving”:
In this method moist heat in form of super heated under
pressure is one of the most effective in destroying
microorganisms including viruses, fungi and spores in
relatively short time, to ensure sterilization; instruction
related to time, temperature, and pressure must be
followed carefully. (For light load of instrument the use
of 20 pounds/inch3 the time should be 20minutes the
temperature 170C ° is enough to kill all M.O)
is rusting of the instrument to minimizeDisadvantage
this instrument must be put in 1% sodium nitrate
solution before autoclaving for 2minutes.

Physical methods:
 4- Hot oil method: this can be used for
sterilization of endodontic instruments and
hand pieces, the temperature .about
150C° and time for 15 minutes.

Physical methods:
5- Ultrasonic vibration method:
We use it especially for reamers, files and
burs. The advantages of this method are:
*16 times more efficient than hand
scraping
** reduce erosion of the instruments
*** reduce puncturing wounds

Physical methods:
 6- Radical sterilization: its efficient
method but expensive we use ultra violet
light , gamma, beta rays. we use this
method to sterilize disposable needles and
drugs.

Physical methods:
7- Gas methods:
Ethylene oxide is used which is highly
bactericidal, Ethylene oxide sterilization is
the best method for sterilizingcomplex
instruments and delicate materials. hand
pieces are sterilized by this method.

Chemical methods:
All chemical disinfectants are poor alternative to
proper physical sterilizing procedure.
Disinfectant antiseptics do not kill all spores , the ways
that these disinfectant acts are:
1-react with the cell protein of the bacteria
2-react with the enzyme system of the bacteria
3- cause disruption of the cell wall of the bacteria

Chemical methods:
properties of ideal antiseptic:
they must destroy the M.O.
it should penetrate deeply through bacterial cell.
Rapid in action
Doesn’t damage material or living tissue when coming
in contact.
Return its potency
Soluble in water
Non corrosion and doesn’t stain the instrument

Chemical methods:
Some points should be taken in consideration
concentration: we should follow the instruction of each
agent before using as a general rule
temperature : higher temperature more efficient
sterilization
P.H.: each agent act perfectly at certain P.H

Chemical methods:
Examples of chemicals used widely in dentistry:
eugenol is pal yellow solution and:eugenol
goes darker with time. Eugenol is protoplasmic
poison (antiseptic)
methylated spirit its protoplasmic:Alcohol
poison , its most effective at concentration of
70%.

Chemical methods:
(camphorated Para mono chlorophynol)C.M.C.P:
Use it in root canal its powerful bactericidal so kill the
bacteria in the canal.
Chlorhexidine : use especially as mouth wash and hand
wash at concentration of 0.12% .its bactericidal against
G+ and G- bacteria but viruses are resistant to it.
Hydrogen peroxide: (H2O2) its mild anti bacteria it
librated O2 rapidly it helps for cleaning pus and debris so
can be used in R.C.T
Sodium hypochlorite: powerful germicidal and good
solvent for necrotic tissue so use it in R.C.T

Combination between chemical
and physical methods
CHEMICAL VAPOR PRESSURE
STERILIZATION (CHEMICLAVING)
Sterilization by chemical vapor under pressure is performed in a
Chemiclave. Chemical vapor pressure sterilizers operate at
270° F (131° C) and 20 pounds of pressures. They are similar
to steam sterilizer’s and have a cycle time of approximately
half an hour.

Combination between chemical
and physical methods
sterilized instruments without rustAdvantages of Chemiclaves:
or corrosion.
Items sensitive to:Disadvantages of Chemiclaves
The elevated temperature will be damaged. Towels and heavy
cloth wrappings of surgical instruments may not be penetrated
to provide Sterilization.

Sterilization in operative dentistry

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