This document provides information on sterilization, disinfection, and antisepsis in dentistry. It discusses the classification of dental instruments as critical, semi-critical, or non-critical based on the risk of infection. Critical instruments that contact bone or tissue must be sterilized after each use, while semi-critical instruments touching mucosa can be high-level disinfected. Non-critical instruments contacting intact skin require low-level disinfection. Common sterilization methods like moist heat via autoclaving and dry heat are described. Autoclaving uses pressurized steam to sterilize at 121-134°C, while dry heat uses hot air ovens or flaming. Chemical indicators, biological indicators,

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2. ALI MUSTAFA MAZHAR
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3. Contents
• Sterilization
• Disinfection
• Antiseptic
• Mechanism of microorganisms killing
• Dental Instruments Classification
Critical , Semi Critical and Non Critical
• Processing cycle
• Methods of sterilization
• Monitoring of sterilization
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4. Sterilization :
It is a process by which an article, surface or medium is made free of all
microorganisms either in vegetative or spore form.
Disinfection :
Destruction of all pathogens or organisms capable
of producing infections but not necessarily spores.
– All organisms may not be killed but the number is
reduced to a level that is no longer harmful to health.
Example: Alcohol,chlorine,bleach
Antiseptics :
Chemical disinfectants which can safely applied to
living tissues and are used to prevent infection by
inhibiting the growth of microorganisms
Example: chlorhexidine, iodine. 4

5. How can microorganisms be killed?
• Denaturation of proteins (e.g. wet heat, ethylene oxide)
• Oxidation (e.g. dry heat, hydrogen peroxide)
• Interruption of DNA synthesis/repair (e.g. radiation)
• Interference with protein synthesis (e.g. bleach)
• Disruption of cell membranes (e.g. phenols)
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6. DENTAL INSTRUEMENTS CLASSIFICATION
CRITICAL
SEMI
CRITICAL
NON
CRITICAL
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7. CRITICAL
Surgical and other instruments that touch bone or penetrate soft tissue
are classified as critical and should be sterilized after each use.
EXAMPLES :
• surgical instruments
• Periodontal scalers
• Scalpel blades
• Forceps
• burs
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8. SEMI CRITICAL INSTRUEMENTS
Instruments that touch mucous membranes, but do not touch bone or
penetrate tissue .• If sterilization is not feasible because the instrument
will be damaged by heat, use high-level disinfection.
EXAMPLES :
• Mirrors.
• Amalgam condensers.
• Dental handpieces .
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9. NON CRITICAL INSTRUEMENTS
Instruments are the one which contact intact skin . Use intermediate-
level or low- level disinfection for them.
EXAMPLES :
• x-ray heads.
• Face-bows
• Blood pressure cuff.
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10. PROCESSING CYCLE
RECEIVING
CLEANING
PACKAGINGSTERLIZATION
STORAGE
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11. Physical methods
Dry Heat
Moist Heat
Ionizing Radiation
Nonionizing Radiation
Filtration
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12. Dry Heat
RED HEAT :Materials are held in the flame of a bunsen burner till they become red hot. »
Inoculating wires or loops » Tips of forceps.
FLAMING: Materials are passed through the flame of a bunsen burner without
allowing them to become red hot. » Glass slides » scalpels » culture tubes.
INCINERATION : Materials are reduced to ashes by burning. Use in contaminated dressings,
chemotherapeutic wastes.
HOT AIR OVEN: Involves heating at atmospheric pressure and often use
a fan to obtain uniform temperature by circulation.
• Heat at 180º for half hour , 170º for 1 hr., or 160º C for 2 hrs.
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13. MOIST HEAT
Moist heat is more effective than dry heat because water is good conductor of
heat than air
Mode of action: Denaturing of protein
TYPES ◦ Boiling ◦ Steam under pressure(autoclaving)
AUTOCLAVING:
Most economical method of sterilization.
Sterilization with steam under pressure is performed
in a steam autoclave.
• For a light load of instruments, the time required at 250 F(121 C) is a
minimum of 15 mins at 15lb of pressure.
• Time can be reduced to 7 mins if the temperature is increased to
approx.273 F(134 C) and pressure is increased to 30 lb. 13

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15. How does autoclave work
The door is locked to form a sealed chamber, and all air within the
chamber is replaced by steam. The steam is then pressurized to reach
the desired sterilization temperature and time, before exhausting the
steam and allowing the goods to be removed.
ADVANTAGE
it kills all forms of microbes, Including
bacterial endospores , which are long
lasting and tough
DISADVANTAGE
Moisture retention, corrodes
carbon steels metals
Destruction of heat sensitive
instruments
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16. Chemical vapor pressure sterilization
(chemiclave)
This sterilizer is same as autoclave unlike it uses special chemical
solution containing formaldehyde and alcohol at 131 degree and 20
lb for 30 mins
Advantage: It does not corrode metals. Load comes out dry.
Disadvantage: High cost of equipment. Vapor odor may be offensive
and requires increased ventilation
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17. Chemical Methods of sterilization
Alcohols:
Kill bacteria, fungi and viruses. Act by denaturing proteins and disrupting cell
membranes
Phenols :
Used for decontamination of hospital laboratory noncritical items. environment
surfaces, medical & for surgical.
Aldehydes:
used to sterilize metal instruments.
Gaseous Sterilizers(Ethylene Oxide):
use to sterilize single-use medical devices.
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18. MONITORING OF STERLIZATION
Heat distribution inside a chamber is usually is measured using thermocouples,
pressure is measured by pressure gauge etc.
Tape, load cards, or labels. Color change on tape is what is often used .
Small, individually packaged spore strips made of special filter paper inoculated
with single species of bacterial spores to monitor, validate, and requalify ethylene
oxide, dry heat, or saturated steam sterilization.
PHYSICAL INDICATOR
CHEMICAL INDICATOR
BIOLOGICAL INDICATOR
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19. Sturdevant's Art & Science of
Operative Dentistry
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