Sterilization and disinfection /endodontic courses

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

DEFINITIONS:

1. STERILIZATION:
Is defined as freeing the object or substance from all
life of any kind
OR
It is defined as the process by which an article, surface
or medium is freed of all micro organisms either in the
vegetative or spore state

2. DISINFECTION:
It means the killing, removal or destruction of
organisms capable of causing infection namely
pathogens
Disinfectant is an agent accomplishing
disinfection it is applicable to inanimate objects

3. ANTISEPTIC:
Closely linked to disinfection, it inhibits or
destroys pathogens and is applicable to
living tissues.

METHODS OF STERILIZATION
a. Mechanical or physical
b. Chemical

MECHANICAL OR PHYSICAL
A. MECHANICAL IS FURTHER CLASSIFIED INTO
1) Sunlight
2) Drying
3) Dry heat- this includes flaming

4. Moist heat includes pasteurization,
boiling, steam under normal and high
pressure, chemical vapor under pressure,

5) Filtration including candles, asbestos,
pads, membranes
6) Radiation
7) Ultrasonic and sonic vibrations.

B.CHEMICALS:
Alcohols, aldehydes, dyes, Halogens,
Phenols, surface active agents metallic salts
and gases

COMMON METHODS OF STERILIZATION

1.STEAM UNDER PRESSURE: Autoclave
The autoclave is the most
common means of sterilization, except when
penetration of steam is limited or heat and
moisture damage is a problem. Moist heat kills
microorganisms through protein coagulation,
RNA and DNA breakdown, and release of low-
molecular – weight intracellular constituents.

The auto clave sterilizes in 15 to 40 minutes
at 249.80
F (1210
C), at a pressure of 15 psi.
The time required depends on the type of
load placed in the autoclave and its
permeability.

Advantages:
1. has a relatively quick turnaround time for
instruments.
2. offers excellent penetration of packages.
3. will not destroy cotton or cloth products.

Disadvantages:
• Materials must be air dried at completion of
the cycle.
• Because certain metals may corrode or dull,
antirust pretreatment may be required. Most
stainless steel instruments are resistant to
autoclave damage.
• can destroy heat-sensitive materials.

2. DRY HEAT
a. Prolonged Dry Heat:
Dry heat sterilization, like chemical
vapor and autoclave sterilization, is verifiable.
Dry heat is very slow to penetrate instrument
loads. Dry heat sterilizes at 3200
F (1600
C) in
30 minutes, but instrument loads may take 30
to 90 minutes to reach that temperature.

Dry heat kills microorganisms primarily
through an oxidation process. Protein
coagulation also takes place depending on
the water content of the protein and the
temperature of sterilization.

Advantages :
 has large load capability
 offers complete corrosion protection for dry
instruments
 Equipment is of low initial cost.

Disadvantages:
• provides slow instrument turnaround because
of poor heat exchange.
• Sterilization cycles are not as exact as in
moist heat sterilization.
• sterilizer must be calibrated and monitored.
• If sterilizer temperature is too high,
instruments may be damaged.

b. Rapid Dry Heat:b. Rapid Dry Heat:
Small chamber high, speed dry heat Sterilizers
have been developed primarily for use in
dentistry. Load limitations exist, but these
devices are much faster than prolonged dry
heat.

Rapid heat transfer Sterilizer

3. Unsaturated Chemical Vapor:
This system, using a device
that is similar to an autoclave, is named a
Harvey chemiclave or chemical vapor
sterilizer.

The principle of chemiclave sterilization is
that although some water is necessary to
catalyze the destruction of all
microorganisms in a relatively short period
of time, water saturation is not necessary.
Like autoclave sterilization, chemical vapor
sterilization kills microorganisms by
destroying vital protein systems.

Chemical Vapor Sterilizer

Uses solutions containing specific amount of
alcohol, ketone, and formaldehyde. Water – less
than 15% When the chemiclave is heated to
2700 F (1320 C) and pressurized to at least 20
psi, sterilization occurs in 20 minutes

Advantages
1. will not corrode metals.
2. has a relatively quick turnaround time for
instrument
3. Load comes out dry.

Disadvantages:
Vapor odor may be offensive, requiring
increased ventilation.
Special chemicals must be purchased.
Can destroy heat sensitive materials

4. Ethylene Oxide Gas:
The extreme penetrability of the ethylene
oxide (ETO) molecule and ETO’s effectiveness
at low temperature (700
to 1400
F; 210
to 600
C) make ETO ideal for sterilizing heat
sensitive materials.

It is best used in a hospital or strictly
controlled environment. ETO is thought to
be potentially mutagenic and carcinogenic,
and its use must be weighed against its
possible benefits.

5. GLUTARALDEHYDE SOLUTIONS:
Whenever possible, reusable dental instruments
should be heat sterilized by a method that can
be biologically monitored. However, some
dental and medical instruments are destroyed
or damaged by the heat of sterilization.

In these cases the use of aqueous
glutaraldehyde preparations for high – level
disinfection or sterilization can be
employed. - biocidal activity

6. HOT SALT STERILIZER:
It consists of metal cup in which table salt is kept at a
temperature between 4250
F and 4750
F (218-2460
C)

Sterilization of instruments:
1. Burs - Autoclave, dry heat, alcohol or flamed
2. Endodontic instruments – Files, Reamers,
Broaches, Absorbent points – hot salt sterilizer
3. Hand Piece- Steam Sterilization - autoclave

Monitoring Sterilization:
There are two methods commonly used to
monitor in-office Sterilization: process
indicators and biologic indicators.

Process indicators:
Are usually strips, tape, or paper products
marked with special ink that changes color
with exposure to heat, steam, or chemical
vapor. The ink changes color when the
item being processed have been subjected
to Sterilizing conditions.

Biologic indicators:Biologic indicators:
Are usually preparations of nonpathogenic
bacterial spores that serve as a challenge to a
specific method of sterilization. If a sterilization
method destroys spore forms that are highly
resistant to that method, it is logical to assume
that all other life forms, including viruses, have
also destroyed.

Sterilization and disinfection /endodontic courses

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