Sterilization in dentistry

methods of sterilization in detail

1. STERILIZATION IN
DENTISTRY
Dr.Madhu Billa
2
nd
year PG
SIBAR Institute Of Dental Sciences

2. Sterilization:- Is defined as the process by which an article,
surface or medium is freed of all living microorganisms
either in the vegetative or in the spore form.
Disinfection:- It is the destruction or removal of all
pathogenic organisms to a level which seems to be no
longer harmful to health
TERMS & DEFINITIONS

3. Contamination:-The presence of microorganisms on a body
surface or on inanimate articles or substances.
Sanitation:-The process by which the number of microorganisms
on inanimate objects is reduced to a safe level. It does not
imply freedom from microorganisms, and generally refers to a
cleaning process.

4. Asepsis:- A condition in which living pathogenic
microorganisms are absent.
Antiseptic:-A substance that prevents or arrests the growth
of action of microorganisms either by inhibiting their
activity or by destroying them.Term used especially for
preparations applied topically to living tissues.
.

5. Infection Control:-The selection and use of procedures
and products to prevent the spread of infectious diseases.
Bactericidal:- These are agents which are able to kill
bacteria.
Bacteriostatic:- These agents prevent the multiplication of
bacteria

6. H
I S
T
O
R
Y
The concept of asepsis & sterilization and its role in the
prevention of infection was put forward nearly Two centuries
ago.
The general principles for asepsis were laid down by
Hungarian gynecologist, Ignaz semmelweis in europe in early
1850’s and Oliver Holmes in USA.
These principles were accepted after Joseph Lister’s studies
on prevention of wound infection carried out between 1865-91.

7.  Lister, working on antisepsis, initially used phenol
(dilute carbolic acid) for contaminated wounds, later
applied it in all surgical wounds, also in operating room by
nebulization of the solution. Further developments
occurred with the introduction of steam sterilization.
Anthony Van Leuwenhock first described
microorganisms (1667).

8. Von Bremann introduced autoclave
Infection control program recommended by the CDC
Federal OSHA published standards on occupational
exposure to blood-borne pathogens in Dece. 1991
Required in every dental office by July 6, 1992

9. CLASSIFICATION OF STERILIZATION
Physical agents Chemical agents
Sunlight Alcohols
Drying Dyes
Dry heat Halogens
Moist heat Phenols
Filteration Surface active agents
Radiation Metallic salts
Ultrasonic and sonic vibration gases

10. SUNLIGHT
 It has bactericidal activity and plays an important role in
spontaneous sterilization that occurs under natural
conditions.
 Action is due to its content of ultraviolet rays, most of
which, however are screened out by glass and the
presence of ozone layer.
Direct sunlight as in tropical countryside where it is not
filtered by impurities in the atmosphere, has an active
germicidal effect due to the combined effect of ultraviolet
and heat rays.

11. DRYING
Moisture is essential for bacteria
Drying therefore has a deleterious effect on most bacteria
Viruses and spores are unaffected by drying
So drying is a very unreliable method.

12. HEAT
It is the most popular, reliable and widely used method of sterilization
Two methods - Dry heat
Flaming
Incineration
Hot Air Oven
- Moist heat
Temp below 100
o
C
Temp at 100
o
C
Steam at normal pressure
Steam under pressure

13. FLAMING
A simple & effective
method
Loops or wires ,glass slides,
cover slips the tips of the
instruments are held in a
Bunsen flame till they
become red-hot. These
materials may be dipped in
a disinfectant before
flaming

14. INCENERATION
 This is an excellent method for safely destroying
materials such as contaminated cloth, animal carcasses
and pathologic materials
Plastics such as PVC and polythene can be dealt with
similarly
Polystyrene materials emit clouds of dense black smoke
and hence should be autoclaved in appropriate containers.

15. HOT AIR OVEN
• This is the most widely used method of sterilization by
dry heat.
•This type of energy does not penetrate materials easily
and thus, long periods of exposure to high temperatures
are necessary.
•A holding period of 160
o
C( 320
o
F) for 1 hr is used to
sterilize glassware, swabs, liquid paraffin, dusting
powder, fats and grease. It is suitable for dry powders and
water free oily substances.

16. •Since hot air is a bad conductor of heat its penetrating
power is low.
• The oven is usually heated by electricity, with heating
elements in the wall of the chamber.
• It must be fitted with a fan to ensure even distribution of
air and elimination of air pockets.
• The material should be arranged so as to allow free
circulation of air in between the objects.

17. Glassware should be perfectly dry before being placed in
the oven.
The British pharmacopoeia recommends a holding period
of 1hr at 150
0
C for oils, glycerol, and dusting powder.
 The oven must be allowed to cool slowly for about 2hrs
before the door is opened, since the glassware may crack
due to sudden or uneven cooling.

18. ADVANTAGES
•Effective and safe sterilization of metal instruments and
mirrors
•No corrosion of Carbon steel instruments and burs
DISADVANTAGES
•Long cycles
•Poor penetration
•Uneven heating
•Damage to heat sensitive items

19. GLASS BEAD AND HOT SALT
STERILISER
The glass bead steriliser uses a metal cup with glass
beads of 1 mm diameter in it
The hot salt container uses ordinary table salt
The temperature range for both varies from 425
o
F TO
475
o
F
Both are used to sterilise endodontic instruments
The hot salt steriliser is better than the glass bead
steriliser because the glass beads stick to the instruments
and clog the root canal.
Also the material used in the hot salt steriliser is ordinary
table salt which is readily available

20. Electric glass bead or hot salt
steriliser

21. Moist heat
Moist heat kills microorganisms by denaturing proteins.
 Denaturation involves changes in the chemical or
physical properties of proteins. It includes structural
alterations due to destruction of the chemical bonds
holding proteins in a three dimensional form. As proteins
revert to a two dimensional form they coagulate &
become nonfunctional.
Moist heat penetrates material much more rapidly than
dry heat because water molecules conduct heat better
than air.

22. TemperaTures below 100
0
C
PASTEURIZATION
•Its purpose is to reduce the bacterial population of a liquid
such as milk and destroy organisms that may cause spoilage
•Spores are not affected by this method

23. Holder method
– It involves heating up to 62.9
0
C for 30 min.
although thermophilic bacteria thrive at this temperature;
they are of little consequence because they cannot grow at
body temperature.
Flash pasteurization
-This method uses a temperature of 71.6
0
C for 1sec
followed by cooling to 13
0
C
Ultra pasteurizat
i
on
-This method uses a temperature of 82
0
C for 3 sec.

24. Temperatures at 100
0
C (boiling)
Vegetative bacteria are killed almost immediately at 90-100
0
C,
but sporing bacteria require prolonged periods of boiling.
Boiling water is not considered as a sterilizing agent because
destruction of bacterial spores and inactivation of viruses
cannot always be assured. It is considered as a method for
disinfection
 A minimum exposure period of 30min. is recommended to kill
vegetative bacteria.
 Sodium bicarbonate 2% conc. is added to increase the
efficiency of process.

25. Advantages
Rapidity, economic , no elaborate equipment, good penetration
and harmless to wide range of dental materials.
Diasadvantages
 dulls the cutting edges
 can also cause corrosion

26. Steam at atmospheric pressure
Also known as compressed or saturated steam
This is an inexpensive method using a Koch or Arnold
steamer.
Principle used is steam under pressure is hotter and higher
the pressure the higher the temperature
Liquids were sterilized by this method at 100
0
C for 30min
on each of 3 successive days.
 Also called fractional sterilization, because a
fraction was accomplished on each day.
Also called Tyndallization after its developer John
Tyndall, and intermittent sterilization because it was a stop
and start operation.

27. During the first day’s exposure, steam kills virtually all
organisms except bacterial spores and it stimulates spores
to germinate vegetative cells.
 During overnight incubation the cells multiply and are
killed on second day.
 Again the material is cooled and a few remaining spores
germinate only to be killed on the 3rd day.
 This method also fails because certain spores ( ex; some
anaerobes ) fail to germinate. A suitable medium for
germination such as broth is required.

28. STEAM UNDER PRESSURE

Moist heat in the form of pressurized steam is regarded as
the most dependable method for destruction of all forms
of bacterial life including spores.
This method is incorporated into a device called the
autoclave.
Over a hundred years ago, French & German
microbiologists developed the autoclave.
The basic principle is that when the pressure of a gas
increases the temperature increases

29. As the water molecules in steam become more energized,
their penetration also increases
Same principle is used in home pressure cooker.
It is important to note that sterilizing agent is moist heat
but not the pressure.

Pressure in autoclave –15lbs/sq. inch
Temperature - 121.5
0
C
Time - 3 to 30 min

30. Autoclave

31. This method can be used for a broad variety of items such
as instruments, clothing, glassware and intravenous
solutions etc.
Limitations:
Plastic ware melts in high heat
Sharp instruments become dull ( corrosion )
Many chemicals breakdown during the sterilization
process, and oily substances cannot be treated since they
do not mix with water.
 A new form of autoclave called the Prevacuum
autoclave has been developed, which draws air out of the
chamber at the beginning of the cycle. The major
advantage of this is minimal exposure

32. Unsaturated Chemical Vapor
Sterilization
This system depends on heat, water and chemical
combination for it’s efficacy
The temperature pressure required is greater than that for
autoclave
It is known as a chemiclave
Instead of distilled water a solution of alcohol,
formaldehyde, ketone, acetone and water is used to
produce the sterilizing vapor

33. Temperature 270
0
F(131
0
C )at 20 pounds pressure for 20
to 40 minutes
Advantages
 short cycle, no rusting or corrosion, dry instruments at
the end of the cycle, automatic preset cycle timing
Disadvantages
 heat sensitivity of instruments, loading dry
instruments, chemical odors and constant monitoring

34. OIL BATHS
Can be used to sterilise metal instruments
It can be heated for a period of 175
0
C for 15 minutes
Disadvantages include poor sporicidal activity, fire hazard,
difficult to remove and constant monitoring

35. FILTRATION
Filters have been used since time immemorial
It is the method of choice for heat labile liquids and
solutions
Early pioneer was Charles Chamberland
Filters are used to purify IV solutions, culture media,
toxoids, beverages etc

36. Types of Filters
CANDLE FILTERS
They are manufactured in different grades of porosity &
have been widely used to purify water for industrial and
drinking purposes. They are of 2 types
Unglazed ceramic filter
Ex; Chamberland & Doulton filters
Diatomaceous earth filter
Ex; Berkefeld & Mandler filters

37. ASBESTOS FILTERS
They are in the form of disposable, single use discs. They
have high absorbing capacity and tend to alkalinize filtered
liquids They are carcinogenic
Ex; Seitz filter
SINTERED GLASS FILTERS
They contain heat fusing finely powdered glass particles
of graded sizes. They have low absorbing capacity and can
be easily cleaned.

38. MEMBRANE FILTERS
They are made up of cellulose esters (acetate &
polycarbonate) or other polymers. They are routinely used in
water purification
This is particularly valuable because bacteria multiply and
form colonies on a plate of culture medium.
Pore size 10 to 0.22μ
NUCLEOPORE FILTER
It is a very thin polycarbonate film with etched hole pore
space of 0.1 to 0.08μ

39. NON IONISING RADIATION
This include infrared rays and ultraviolet rays
Infra red rays is used for mass sterilization of syringes

40. ULTRAVIOLET LIGHT
When microorganisms are subjected to UV light, cellular DNA
absorbs energy & adjacent thymine molecules link together.
 Linked thymine molecules are unable to position adenine on m RNA
molecules during the process protein synthesis thereby replication of
chromosome will be impaired.
The damaged organism can no longer produce critical proteins or
reproduce.
 UV light is used to limit airborne or surface contamination in a
hospital room, pharmacy food service operation.
UV light does not penetrate liquids or solids and it may cause
damage to the human skin.

41. IONIZING RADIATION
X-rays and gamma rays have wave length shorter than
UV light
As these rays can pass through microbial molecules, they
force electrons out of their shells, thereby causing
ionisation.
The ions quickly combine with & destroy proteins and
nucleic acid such as DNA, causing death. Gram +ve are
sensitive than gram –ve bacteria.
Can be used for syringe sterilization

42. MICROWAVE
Microwaves have a wavelength longer than UV light.
 In a microwave oven waves are absorbed by water molecules.
 The molecules are set into a high speed motion, and the heat
of friction is transmitted to food, which become hot rapidly.

43. LASER
LASER – Light Amplification by Stimulated Emission of
Radiation
Resent experiments indicate that laser beams can be used to
sterilize instruments & the air in operating rooms, as well as
for a wound surface.
Various types include CO
2

, Argon ,NdYAG etc

44. Ultrasonic vibrations
They are high frequency sound waves beyond the range of
human ear.
 When propagated in fluids ultrasonic vibrations cause
formation of microscopic bubbles or cavities and the water
appears to boil.
 Some observers call this cold boiling.
The cavities rapidly collapse & send out shock waves. The
formation and implosion of the cavities is known as
cavitation. Microorganisms in the fluid are quickly
disintegrated by the external pressures.
The current trend is to use ultrasonic as a cleaning agent to
follow the process by sterilization in an autoclave.

45. FREEZING
Freezing can both kill and preserve depending on various
factors
It’s primary use has been in the preservation of bacterial
cultures.
Repeated freezing and thawing are much more destructive
to bacteria than prolonged storage at freezing temperature.
 If bacteria are rapidly subjected to temperature below –
35
0
C, ice crystals that form within the cell produce a lethal
effect during defreezing.

46. CHEMICAL METHODS OF
STERILIZATION

47. Infection control with chemicals
IDEAL REQUIREMENTS of a chemical disinfectant
1. Broad spectrum
2. Fast acting
3. Non toxic
4. Surface compatibility
Should not corrode instruments and other metallic
surfaces and cause disintegration of cloth, rubber or
other materials

48. 5. Easy to use
6. Odourless
7. Economical
8. Be stable
9. High penetrating power
10. Should not cause local irritation and sensitivity
11. High solubility
Should be soluble in water and have a substantial shelf
life

49. Infection control in dentistry requires the use of
disinfectants in several forms
1.Surface disinfectants
2.Immersion sterilants
3.Immersion disinfectants
4.Hand antimicrobials

50. •Surface disinfection is the treatment of
envioronmental surfaces such as cabinets, chairs, lights,
x-rays and similar surfaces where the items are too large
or sensitive to be immersed in disinfecting chemicals. It
is accomplished by spraying or wiping the solution on the
surface
•Immersion disinfection also called cold
sterilisation is the immersion of instruments, plastics, in a
liquid disinfectant. Time is usually 5 to 30 minutes

51. •Immersion sterilization is the use of an agent that
has the capability of killing all living microorganisms and
infective agents in 6 to 10 hours. The items should be
completely immersed in the solution
•Hand antimicrobial treatment it is the specific
art of washing or otherwise treating hands with a
chemical soap or lotion with resulting reduction in the
number of hand microbes

52. A classification of chemical disinfectants was proposed by
Spaulding in 1972
It was originally developed for classifying hospital
instruments but now has been modified for dental
instruments
Patient care items are classified --
• critical
• semicritical
• non critical
Three levels of disinfection are -- High
Intermediate
Low

53. PATIENT CARE ITEMS
CRITICAL:-
Penetrate or touch broken skin or mucous membranes.
Needles, Scalpels, surgical instruments, mirrors, dental
explorers.
SEMICRITICAL:-
Touch intact mucous membranes.
Amalgam condensers, handpieces ultrasonic cleaners.
NON CRITICAL:-
That do not touch mucous membranes.
Counter tops, light handles, chair surfaces.

54. LEVELS OF DISINFECTION
1.High level disinfection – these disinfectants must
inactivate resistant bacterial spores and all other
microbial forms
E.g. ethylene oxide gas, immersion gluteraldehyde
solutions
2. Intermediate level disinfection– these disinfectants do not
inactivate spores during routine use but they destroy
other forms of microbes
E.g. formaldehyde, chlorine compounds, iodophors,
alcohols, phenolic compounds

55. 3. Low level disinfectants - provide the narrowest
antimicrobial range
E.g. quaternary ammonium compounds, simple phenols
and detergents. Such compounds are suitable for
cleaning environmental surfaces

56. ALCOHOL
Effective skin antiseptics and valuable disinfectants for
medical instruments.
Ethyl and isopropyl alcohol are most frequently used
Isoprpyl alcohol is prefered to ethyl alcohol as it is a better fat
solvent ,more bactericidal and less volatile
It is active against vegetative bacterial cells, including the
tubercle bacillus,
It denatures proteins & lipids, and leads to cell membrane
disintegration
It is also a strong dehydrating agent.
 It is used to sterilize the skin prior to cutaneous injections .

57. It is active against gram +ve, -ve, & acid fast organisms
at a concentration of 50-70%
‘Isopropyl alcohol’ or ‘rubbing alcohol’ has high
bactericidal activity in concentration as high as 99%.
DISADVANTAGES
Relatively inefficient in the presence of blood and saliva
Lacks sporicidal activity
Causes corrosion of metals

58. ALDEHYDES
GLUTERALDEHYDE
 2% solution is effective. It destroys vegetative cells
within 10 min to 30min and spores in 10 hrs
It is recommended for use on surgical instruments where
residual blood may be present.
It does not damage delicate objects, and therefore it can be
used to sterilize optical equipment such as the optic fiber
endoscopes.

59. DISADVANTAGE
It can damage many metal items.
E.g. nickel coated impression trays & carbon steel burs
will often discolour and corrode, respectively when
immersed in gluteraldehyde solution for prolonged periods
It can cause hypersensitivity on repeated exposure so
instruments immersed in gluteraldehyde should be
thoroughly rinsed in sterile water prior to use

60. FORMALDEHYDE

It is gas at high temperatures & solid at room temperature.
In aqueous solutions, it is bactericidal, sporicidal and
virucidal.
When 37 gms. of the solid are suspended in 100ml of
water a solution called formalin results.
 Formalin is utilized for inactivating virus in vaccines &
producing toxoids from toxins.
10% Formalin containing 0.5% sodium tetraborate is used
to sterilize clean metal instruments.

61. In the gaseous form, formaldehyde is expelled into a closed
chamber where it is used as a sterilant for surgical
equipment, hospital gowns and medical instruments.
However penetration is poor and the surface must be
exposed to the gas for up to 12hrs. for effective sterilization.
( Fumigation)
Formaldehyde leaves a residue and instruments must be
rinsed before use.
 Can cause hypersensitivity reactions

62. HALOGEN
 These are a group of highly reactive elements whose
atoms have 7 electrons in the outer shell.
Two halogens chlorine & iodine are commonly used for
disinfection.

63. CHLORINE
Available as -- gas
- organic compound
- inorganic compounds
Most commonly used as hypochlorites
The disinfectant action results from it’s ability to liberate free
chlorine.
 In aqueous solutions the liberated Cl ions reacts with water to
form hypochlorous acid,

64. Used in water supplies and swimming baths
Chlorax & purex bleach used for household sanitation &
the disinfection of food utensils.
Chlorinated lime [NaOCl or Ca (OCl)2] is used as
bleaching agent in textile industry.

65. DAKIN’s solution
0.5% sodium hypochlorite
Extensively for wounds during the I & II World War
 It is used to treat athlete’s foot

66. Chloramines

Chloramines-T are organic compounds
Chlorine and amino groups.
Compounds release free chlorine more slowly than
hypochlorite solutions
More stable.
Used for general wound antisepsis and root canal therapy

67. DISADVANTAGES
Corrosive to metals
Irritating to the skin
Destroys fabrics
Solution has to be prepared daily

68. IOdINE
Iodine is more reactive and more germicidal.
Iodine acts on the tyrosine portions of protein molecules.
Tincture of iodine
2% iodine solution in ethyl alcohol used as an antiseptic for
application over skin and mucous membrane
dISAdVANTAGES
Irritating
Allergic
Corrodes metal
Stains skin and clothes

69. IOdOpHORS
Compounds of iodine with non ionic surface active agents
that release iodine over a long period of time
The detergent portion of the complex loosens the organisms
from the surface & halogen kills them.
AdVANTAGES
Less allergic
Less irritating to tissues
Do not stain clothes
Prolonged activity

70. pHENOLS ANd THEIR dERIVATIVES
(CARbOLIC ACId)
Obtained by distillation of coal tar between
temperatures of 170
0
C and 270
0
C.
Surgical antiseptic by Lister in 1865, phenol was
widely used as a disinfectant.
Low solubility in water, they are formulated with
emulsifying agents, such as soaps, which also increase
their antimicrobial action.
They act as cytoplasmic poisons by penetrating and
disrupting cell wall, thereby leading to denaturation of
intracellular proteins

71. Phenol is active against gram +ve bacteria
Bactericidal at 1% and fungicidal at 1.3 %
Drawbacks
Its activity is reduced in the presence of organic matter
Expensive
Caustic to the skin

72. CRESOL
Phenol derivatives containing methyl groups have greater
germicidal activity and lower toxicity than the parent
compound.
Ortho, meta, para cresols are appreciably more active
than phenol and are employed as a mixture named
“Tricresol”
They are not readily inactivated in the presence of
organic matter and so are good disinfectants

73. Bisphenols
It is a combination of 2 phenol molecules
Eg. .Hexachlorophene, Chlorhexidine
Hexachlorophene
It is highly effective against gram –ve organisms esp.
staphylococci & streptococci.
In 1961 routine daily hexachlorophene bathing of newborn
infants became an accepted procedure in many nurseries in
order to reduce colonization of umbilical stump & infection of
scalp with streptococcus aureus.
 In 1971, FDA placed strict controls on the use of
hexachlorophene and curtailed its use in newborn nursery
because numerous studies indicate that excessive amounts
could be absorbed through the skin and cause neurological
damage in newborn.

74. SURFACE ACTIVE AGENTS
Substances that alter the energy relationships at interfaces
producing a reduction of surface tension are referred to as
surface-active agents.
 They are widely used in industry as wetting agents,
detergents.
 Surface active agents are compounds that possesses both water
attracting (hydrophilic), and water repelling (hydrophobic)
groups.
There are 4 types of surface active agents.
–Cationic surface active agents
–Anionic surface active agents
–Nonionic surface active agents
–Amphoteric surface active agents

75. Cationic Surface Active Agents (quaternary
ammonium compounds )
They act on the phospholipid present in the cell
membrane, then the non polar portion of the detergents
penetrate into the hydrophobic interior of the membrane.
This changes the permeability of the cell
It then enters the cell and causes denaturation of the
protein
More active at an alkaline pH.
They are bactericidal for a wide range of organisms,
although gram +ve species are more susceptible.

76. Disadvantages
Inability to penetrate organic debris
Incompatible with anionic detergents, Ca, Mg, and iron of hard
water
E.g. cetyl trimethyl ammonium bromide (cetavlon or ctrimide)
& benzalkonium chloride

77. Anionic surface active agents
These are active at acid pH
These agents cause gross disruption of the lipoprotein
framework of the cell membrane and also have
mechanical cleansing action.
e.g. Soaps and fatty acids

78. Nonionic surface-active agents
These agents are relatively nontoxic and few promote
bacterial growth.
E.g. Tween 80 facilitates the diffused growth of
mycobacterium tuberculosis and provides a source of
oleic acid which is stimulatory to the organism.

79. Amphoteric surface active agents
These compounds are also called as TEGO’ compounds.
They are active against a wide range of gram +ve, -ve
organisms and some viruses.

80. Ethylene oxide
Ethylene oxide is a gas at temperature above 10.8
0
C
It has excellent penetration capacity and is sporicidal as
well as virucidal.
 However, it is both toxic and highly explosive.
 Its explosiveness is reduced by mixture with Freon gas
 The gas is released into tightly sealed chamber where it
circulates for up to 4hrs. with carefully controlled
humidity.
 The chamber then must be flushed with inert gas for 8-
12hrs. To ensure that all traces of ethylene oxide are
removed otherwise, the chemical will cause “cold burns”
on contact with skin.

81. It is used to sterilize paper, leather, wood, metal and
rubber as well as plastics.
In hospitals it is used to sterilize catheters, artificial heart
valves, heart-lung machine components and optical
equipment.
Used in chemiclaves

82. Beta Propiolactone (BPL)
It is a condensation product of ketone and formaldehyde
Is less explosive than ethylene oxide, but its penetrating power
is more limited.
 As a liquid it is used to sterilize vaccines, sera and surgical
ligatures.
However, it is carcinogenic & is therefore used only under
restricted conditions.

83. OXIDANTS
Included in this group are halogens, hydrogen peroxide,
and potassium permanganate.
The oxidizing agents inactivate enzymes by converting
functional –SH groups to the oxidized form.

84. Hydrogen Peroxide
(H
2
o
2
)
Rinse wounds, scrapes and abrasions.
The area foams & effervescence as catalase in the tissue
breaks down hydrogen peroxide to oxygen & water.
The furious bubbling removes microorganisms
mechanically.
Anaerobic bacteria are sensitive to H
2
O
2
because sudden
release of oxygen gas inhibits their growth

85. CHLORHEXIDINE
This compound was approved in 1976 by FDA as
surgical scrub, hand wash, and superficial skin wound
cleanser.
Chlorhexidine in a conc. of 0.2% is also most effective
antiplaque & antigingivitis agent

86. After each patient use, run any handpiece that is
connected to the dental air/water system, to discharge
water and/or air for at least 30 seconds after each patient
use
Leave the bur in place while you clean the outside of the
handpiece with detergent and warm water.
Sterilise in an autoclave.
If recommended by the manufacturer, lubricate the
handpiece with pressurised oil until clean oil appears from
the chuck.
STERILISATION OF
HANDPIECES

87. Tests for sterilization
Chemical indicators:
•External chemical indicator
•Internal chemical indicator
Biologic indicator
Microorganisms used
Steam autocalve:
Bacillus stearothermophillus in vials,strips
Dry heat oven : Bacillus subtilis strips
Chemical vapour: Bacillus stearothermophillus on strips

92. ConCLUSion
“PREVENTION IS BETTER THAN CURE” - a
proverb well suited to sterilisation
A thorough understanding of the application of
sterilisation will help ensure safety from the invisible but
deadly world of microbial pathogens
Hence utilisation of proper sterilization, disinfection and
aseptic procedures helps us achieve the safety of our
professional demands

93. reFrenCeS
•Textbook of microbiology- R.Anantnarayan 7th Edition
Orient Longman
•Fundamentals of microbiology- Frobisher 9
th
Edition
Saunders
•Infection control and office safety- DCNA April 1991
•Clinical Practice of the Dental Hygienist- Esther M
Wilkins 7
th
Edition