Sterilization

1. 1
Sterilization
and
disinfection
Presented By :
Dr. Vartika Srivastava
P.G. Ist year

2. Contents
Introduction
Definitions
Objectives
Instrument cleaning step
Packaging step
Method of sterilization
Test for sterilization
Care of sterile Instruments
2

3. Disinfectants
Preparation of treatment room
Unit water lines
Patient preparation
Occupational Accidental Exposure
Management
Conclusion
References
3

4. •Micro organisms are ubiquitous. Since they cause
contamination, infection and decay , it becomes
necessary to remove or destroy them from
materials or from areas.
•Sterilization procedures used in dentistry should
be simple but effective and of relatively short
duration.
4

5. LOUIS PASTEUR of France was among the
first to use sterilization techniques, he developed
the steam sterilization, hot air oven and the
autoclave. Pasteurization was a method
developed by him to rid of tubercle bacilli from
milk.
JOSEPH LISTERJOSEPH LISTER,, applied Pasteur's work and
introduced antiseptic technique in surgery
(1867). He is the father of antiseptic surgery.
5

6. 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.
6

7. SEPSIS :
Refers to presence of infection, infectious material
or agent
ASEPSIS :
 freedom from infection,
 prevention of contact with pathogens
7

8. INFECTION :
Invasion of the body tissues by the pathogenic
bacteria
INFECTION CONTROL :
Prevention of spread of micro-organisms from
their hosts
Killing or removal of micro-organisms from
objects and surfaces
8

9. CONTAMINATION :
Contamination is the presence of a minor and
unwanted constituent in a material, in a
physical body, in the natural environment, at a
workplace, etc. . .

Decontamination:
It is the process of removal of contaminating
pathogenic microorganisms from the articles by a
process of sterilization or disinfection
9

10. ANTISEPTIC :

Refers to a chemical agent that is used on or in
living tissues to kill or prevent the growth of
microbes.
AEROSOL:
Invisible airborne particles dispersed into the
surrounding environment by dental equipment
(e.g., handpieces, electronic instruments).
10

11. OBJECTIVES
11

12. TREATMENT ROOM
FEATURES
12

13. DENTAL CHAIR
•Controls all foot operated
•If manually operated needs disposable cover
for buttons
•Surface should be made up of plastic material
that withstand chemical disinfection without
damage or discoloration .
13

14. 14

15. LIGHT
Foot operated switches
Removable handle for sterilization or
disposable barrier control
15

16. CLINICIAN STOOL
Smooth , plastic material that is easily
disinfected and has a minimum of seams and
creases
Foot operated controls
16

17. FLOOR
•Carpeting should be avoided
•Floor covering should be smooth , easily
cleaned and non absorbent.
17

18. SINK
•Smooth material (stainless steal)
•Wide and deep for effective hand washing
without splashing
•Water faucets and soap dispensers with
electric knee or foot controlled
18

19. WASTE
•Heavy duty plastic bags linear to be sealed
tightly for disposal.
19

20. 20

21. CLEANING STEP

ULTRASONIC PROCESSING

 MANUAL PROCESSING

PACKAGING STEP


21

22. MANUAL CLEANING
PROCESSING

cleaning of instrument should be done before
sterilization
22

23. PROCEDURE
Wear heavy duty gloves and mask
Dismantle instruments
Use detergent and scrub
Brush with strokes away from the body
Rinse thoroughly
Dry on paper towel
23

24. ULTRASONIC PROCESSING
STEP
Ultrasonic cleaning prior to sterilization is safer
than manual cleaning
24

25. ADVANTAGES
Increased efficiency
Reduced danger to clinician from direct
contact
Penetration into areas of instruments
where the bristle of a brush may be unable
to contact
Removal of tarnish
25

26. Procedure
Instrument must be completely immersed
Dismantle instruments with detachable
parts
Time accurately by manufacturer’s guide
Drain , rinse and air dry
26

27. Often instruments are packed for sterilization to
be stored and handled without being
contaminated.
Packing depend on the intended shelf life after
sterilization.
The available packing options are:
Textile has shelf life of 1 month
Paper has shelf life of 1 – 6 months
Nylon, glass, and metal have shelf life of 1 year if
tightly closed
27

28. Tips on wrapping and packaging
28
Make sure the instruments don’t protrude
from package.
more than two layers of wrap.
Place biologic or chemical indication along
with packages.

29. 29

30. Physical agents
1. sunlight
2. drying
3. dry heat
- red heat
- flaming
- incineration
- hot air oven
- glass bead sterilization
- ethylene oxide Gas Sterilization

30

31. 4. moist heat
- pasteurization
- boiling
- steam under normal pressure
- steam under pressure
5. filtration
- candles
- asbestos pad
- membranes

6. radiation
7. ultrasonic and sonic vibrations
31

32. Chemical agents
1. alcohols
- ethyl alcohol
- isopropyl alcohol
- trichloro butanol
2. aldehydes
- formaldehyde
- glutaraldehyde
3. dyes
4. halogens
5. surface active agents
6. metallic salts
7. gases
32

33. •Sunlight possess appreciable bacterial
activity and plays an important role in the
spontaneous sterilization that occurs
under normal conditions
•The action is mainly due to UV rays
•Direct sunlight has germicidal activity.
33

34. •Moisture is essential for growth of
bacteria.
•Drying in air has therefore a deleterious
effect.
•This is unreliable, spores are unaffected.
34

35. The factors influencing sterilization by heat
are
1.Nature of heat.
2.Temperature and time
3.Number of microorganisms
4.Characteristics of organisms
5.Type of material from which organisms
have to be eradicated.
35

36. Red Heat
sterilized by holding them in
Bunsen flame till they become
red hot.
USE :
bacteriological loops
straight wires
tips of forceps and searing
spatulas
36

37. •This is a method of passing
the article over a Bunsen
flame, but not heating it to
redness,

USE :
Scalpels
mouth of test tubes,
Flasks
glass slides
cover slips
37

38. •This is a method of
destroying contaminated
material by burning them
in incinerator.
USE :
soiled dressings
animal carcasses
pathological material
bedding etc
38

39. This is the most widely used
method of sterilization by dry
heat.
39
TEMPRATURE TIME (minutes)
160 °c 120
170° c 60
150° c 150
140° c 180

40. Advantages:-
1.Is effective and safe for sterilization of
metal instruments and mirrors.
2. Does not dull cutting edges.
3. Does not rust or corrode.
40

41. Disadvantages:-
1.Requires long cycle for sterilization except
for forced air.
2.Has poor penetration.
3.May discolor and char fabric.
4.Destroys heat labile items.
5.Cannot sterilize liquids.
6.Unsuitable for hand pieces.
7.Cooling of the oven takes a long time.
41

42. Uses:
Forceps
Scissors
Scalpels
Swabs
glass ware
petri-dishes
Pipettes
Flasks
all glass syringes.
Pharmaceuticals products like Liquid paraffin,
dusting powder, fats and grease
42

43. Glass bead sterilization
Used to sterilize endodontic instruments
210°c – 230°c for 10-30 sec.
43

44. Ethylene oxide, a gas at temperatures above
108°C, is a highly penetrative, non corrosive
agent with a cidal action against bacteria,
spores and viruses.
It destroys microorganisms by alkylation; and
causes denaturation of nucleic acids
44

45. 45

46. Uses:
Plastic goods
polythene tube
artery and bone grafts
vaccines
culture media
46

47. Pasteurization
•Used to kill bacteria in raw milk.
•Holder Method – 63 °c for 30 mins
•Flash Method -72°c for 15 -20 sec
followed by quickly to 13°c or lower
47

48. 48

49. Hot Water Bath
To inactivate non sporing bacteria for the
preparation of vaccines - Special vaccine
bath at 60
o
C

for one hour is used
Serum or body fluids containing coagulable
proteins can be sterilized by heating for 1 hr
at 56
o
C in a water bath for several
successive days.
49

50. 50

51. Inspissator
Sterilizes by heating at 80-85
o
C for half an
hour for 3 successive days
Used to sterilize media such as Lowenstein-
Jensen & Loefller’s serum
51

52. 52

53. TEMPERATURE AT
100
O
C
Boiling:
Kills vegetative forms of bacterial
pathogens.
Hepatitis virus: Can survive up to 30
minutes of boiling.
Endospores: Can survive up to 20 hours or
more of boiling
53

54. Disadvantage
Time consuming
Does not destroy spores
Cutting instruments should not be
sterilized by boiling as they loose their
sharpness.
54

55. 55

56. A single exposure of 90 min usually
ensures sterilization but for media
containing sugars or gelatin an exposure
of 100c for 20 min on 3 successive days
is used. This is known as
TYNDALLISATION or INTERMITTENT
STERILISATION.
56

57. Invented by Charles Chamberland in 1879

Autoclaves -2 types.

1.Porous load autoclave
2.Small bench top automatic autoclave
Temperature -136°c;
Pressure-32pounds;
Cycle time-5min
flash sterilization.
57

58. •Denaturation and coagulation of microbial
proteins occur during exposure to the high
temperature of the steam.
Temperature: 121c
Pressure : 15psi
Cycle time :15-20 min.
Packing material must allow steam to
penetrate
58

59. 59

60. Advantages:

1. Short efficient cycle time.

2. Good penetration.

3. Ability to process a wide range of
materials.

.
60

61. Disadvantages
1.Corrosion of unprotected carbon steel.
2.Dulling of unprotected cutting edges.
3.Possibility that packages may remain wet at end
of cycle.
4.Possible deposits from use of hard water.
5.Possible destruction of heat sensitive materials.
61

62. This method uses a combination of dry
saturated steam and formaldehyde to kill
bacteria, spores and most viruses.
Formaldehyde acts by alkylation of the
nucleic acids
The required combinations of temperature
and pressure are 127 to 132°C at 20 to 40
psi for 30 minutes.
62

63. 63

64. For sterilization of :
Endoscopes
Cardiac catheters
 Respiratory equipment
64

65. Filtration :-

Filtration helps to remove bacteria from
heat
labile liquids such as sera and solutions of
Sugars or antibiotics used for preparation of
Culture media.
65

66. Following types of filters are used-
1.Candle filters- purification of water for
industrial and drinking purposes.
2.Asbestos filters-
•Disposable, single use discs.
•They have high adsorbing capacity
• Alkalinize filtered liquids.
66

67. 67

68. 3.Sintered glass filters-
• Are prepared by heat fusing finely
powdered glass particles of graded sizes.
•low absorptive property
•brittle and expensive.
4.Membrane filters-
•Routinely used in water purification and
analysis,
•sterilization and sterility testing
•preparation of solutions for parenteral use.
68

69. Radiation

Two types of radiation are used for
sterilization.
1. Non ionizing and
2. Ionizing.
Non ionizing - Infra red and UV rays.
Ionizing - Gamma rays and high energy

electrons.
69

70. Non Ionizing Radiation
•Electromagnetic rays with longer
wavelengths are used.
•Infra red radiation is considered as a form
of hot air sterilization.
70

71. USE
• Rapid mass sterilization of pre packed
items such as syringes and catheters.
•Disinfecting enclosed areas such as
entryways, operation theatres and
laboratories.
71

72. Ionizing radiation-

Also referred as cold sterilization
 X- rays, gamma rays and cosmic rays are
highly lethal to DNA and other vital
constituents.
They have high penetrating power, since
there is no appreciable increase in
temperature.
72

73. USE
•Commercial plants use gamma radiation for
sterilizing items like plastics, syringes,
swabs, catheters, animal feeds, oils,
greases, fabrics etc.
73

74. Ultrasonic and sonic waves are credited
with bactericidal powers but the results
have been variable.
Microorganisms vary in sensitivity to them,
survivors are found even after treatment.
Hence it has no practical value in
sterilization and disinfection.
74

75. 75

76. To be continued ……
76

77. 77 C o n t a t m i C t D E N
i E T N T t A t E L o H C t D E
Sterilization
and disinfection

78. CONTENT
Chemical agents
Classification of instrument to be sterilized
Test for sterilization
Disinfectants
Infection in dental operatory
Universal precaution
Patient preparation
Unit water line
Occupational accidental exposure management
Waste
Osha regulation
78

79. Chemical Agents
79

80. 80

81. Wide spectrum of activity
Active in the presence of organic matter
Effective in acid as well as alkaline media
Speedy action
High penetrating power
Stable
Compatible with other antiseptics and Disinfectants
Not corrode metals
81
IDEAL CHEMICAL DISINFECTANT

82. Not cause local irritation or sensitization
Not interfere with healing
Not be toxic if absorbed into circulation
Cheap and easily available
Safe and easy to use
82

83. 83

84. Alcohols :
Ethanol /Isopropyl alcohol are frequently
used
No action on spores
Concentration recommended 60-90% in
water
Uses
Disinfection of clinical thermometer.
Disinfection of the skin

84
Spectrum: Effective against fungi, vegetative
bacteria, Mycobacterium species and some
lipid-containing viruses

85. Limitation: Not effective against
spores.
Concentration: Most effective at
70% in water.
Caution: Do not use near flames
due to flammability.
May swell rubber or harden
plastics.
85

86. Aldehydes
FORMALDEHYDE
To preserve anatomical specimens
Destroying Anthrax spores in hair and wool
10% Formalin+0.5% Sodium tetra borate is used
to sterilise metal instruments
86

87. Formaldehyde gas
It It is used for sterilizing instruments and heat
sensitive catheters, for fumigating wards, sick
rooms and labs.
.
87
Caution: Formaldehyde can react with free
chlorine to produce toxic gas.

Irritant vapours are released hence
Neutralise with ammonia following
decontamination

88. 88
FUMIGATION

89. 89
Concentration: Glutaraldehyde is
commercially available as 2% w/v
aqueous solution which must be made
alkaline to "activate" um $%maLSNDiDLEIpcEImHCLSNnColmWCimDNm
LIDHNm&'mpCSiH lmADomrImSHIEmNCm
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A 2% glutaraldehyde solution, for at
least 10 hours, can be used to
sterilize heat labile items.RGIANiSOF muANnUImDaDnoHNm UIaINDNnUIm
rDANIinDlmHGCiIHlmWSoanmDoEmODocm
UniSHIH e
Spectrum: Active against vegetative
bacteria, spores, fungi and many
viruses.

90. 90 S i F
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riCoApCHACGIHlm
ACiiSaDNIEmiSrrIim
DoIHNpINnAmNSrIHlmWDAIm
ODH(HlmIoECNiDApIDLm
NSrIHlmOINDLmnoHNiSOIoNHlm
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Use:
for instruments such as,
bronchoscopes,
corrugated rubber
anesthetic tubes, face
masks, endotracheal
tubes, metal instruments,
polythene tubing.

91. Caution:
 Glutaraldehyde is known to cause dermatitis and
asthma.
It should not be used in an area with
little or no ventilation.
Eye protection, a plastic apron, and gloves must be
worn
Should be stored away from heat sources and in
containers with close-fitting lids.
The length of time that glutaraldehyde solutions can
be used varies but they are usually good for up to 14
days.
91

92. 92
Dyes

93. HALOGENS HALOGENS

93

94. Phenols
These are obtained by distillation of coal tar
between temperatures of 170c and 270c
Powerful microbicidal
 Phenolic derivatives have been widely used as
disinfectants for various purposes in hospitals
Eg: Lysol, cresol
,
94

95. use :
To clean wards
Various combinations are used in the control of
pyogenic cocci in surgical & neonatal units in
hospitals.
Aqueous solutions are used in treatment of
wounds
95

96. Metallic salts
Salts of silver, copper and mercury are used as
disinfectants.
Act by coagulating proteins
Marked bacteriostatic, weak bactericidal and
limited fungicidal activity
96

97. CLASSIFICATION OF INSTRUMENTS
TO BE STERILIZED
97

98. 98
critical
Semi critical
Non critical

99. Improper cleaning of instruments
Improper packing
Improper temperature in sterilizer
Improper loading of sterilizer
Improper timing of sterilization cycle
99

100. Take the sterilizer out of service
Procedures to identify problems
Retest and observe the cycle
Determine the fate of sterilizer
Test the repaired or new sterilizer
100

101. Test for sterilization
Different micro-organism and chemical
indicators
are used for test .
Micro – organism used :
Steam autoclave –
Bacillus stearothermophilus vails ,
ampules or strips.
Dry heat oven –
Bacillus subtilis strips.
Chemical vapour –
Bacillus stearothermophilus strips.
Ethylene oxide –
Bacillus subtilis strips
101

102. Commonly used disinfectants
•Sodium hypochlorite (0.1- 0.5%)
•Cidex(2% glutaraldehyde)
•Chloramine 2%
•Ethylalcohol [70% to 90%]
•Formaldehyde 8% and Formalin 20%
•Bisguanides.
•Povidine –iodine (2.5%)
•Phenols
102

103. Broad spectrum of action
Fast acting.
Not affected by physical factors
Non toxic
Surface compatability
Should not have residual effect on treated
surfaces.
Easy to use.
Odourless
Economical
103

104. 104

105. As a stop gap measure, to use only until the
sterilizable instruments can be obtained.
For use in surgical hand washing preparations
For disinfection of environmental surfaces
contacted during an appointment.
For disinfection of dental appliances prior to
insertion into a patients mouth.
105

106. Autogenous infections
Cross infections.
106

107. Are those caused by microbes that the patient
carries on or in his or her own body.
Many of the procedures in dentistry are invasive
and open the tissues to infections by micro
organisms. These microbes usually are harmless
within the oral cavity, but may cause disease if they
enter the tissues.
Eg: infective endocarditis, oral abscesses.
107

108. Many autogenous infections can be prevented by
preoperative prophylactic therapy.
Eg: endocarditis is prevented by the use of
antibiotics.

108

109. Are caused by infectious agents that are
transmitted among dental personnel, patient and
the environment.
The transfer of disease may be from dentist to
patient or vice versa.
Eg: hepatitis B is an occupational hazard for dental
personnel , on the other hand there are evidences
of dentists transmitting hepatitis B.
109

110. Patient to practitioner
Practitioner to patient
Patient to patient
Clinic to community
Clinic to practitioners family
Community to patient.
110

111. Blood and certain body fluids of all patients are
considered potentially infectious
Universal precautions include use of gloves,
gowns, aprons, masks, protective eye wear
Precautions to prevent injuries caused by needles,
scalpels and sharps
111

112. Clinical attire
Use of face mask
Gloves
Protective eye wear
112

113. Wearing apparel is vulnerable to contamination
from spatter, splash, aerosols and patient
contact
Gowns should be clean and maintained free
from contamination
High necked, long sleeved, knee length
Should be changed when visibly soiled
Disposable head caps should be worn to prevent
hair from contamination
Plastic or disposable apron
113

114. Surgical masks or chin length face shields must be
worn to protect face, oral mucosa and nasal
mucosa.
Masks should have 95% filtration efficiency of 3 to
5µm in diameter
Should be changed for each patient
Chin length face shield may be worn
114

115. 115

116. No contact with the wearers lips and nostrils
Has a high bacterial filtration efficiency rate
Fit snugly
No fogging of eye wear
Convenient
Made of material that does not irritate
Does not collapse during wear or when wet
116

117. Is necessary to prevent physical injuries and
infections of the eyes.
Contamination can be introduced from saliva,
biofilm, carious material, pieces of old restorative
materials during cavity prep, bacteria- laden
calculus during scaling and micro-organism in
aerosols or spatter.
Trans conjunctival transmission of hepatitis B
reported – but rare.
117

118. 118

119. Hands serve as a means of transmission of blood,
saliva, dental biofilm
Finger nails serve as a reservoir for micro-
organisms
Skin breaks serve as a port of entry.
119

120. Maintain clean, smoothly trimmed, short finger nails
Remove hand and wrist jewelry
Never expose open skin lesions or abrasions to
patients oral fluids or tissues
After glove removal, wash hands thoroughly
120

121. 121

122. Wearing gloves is the standard practice to protect
both the patient and clinician from cross
contamination
Properly fitting gloves protect from exposure
through cuts and abrasions often found on hands.
122

123. 123

124. Always glove and DE glove in front of patient
Place gloves over cuff of long sleeved clinic wear
Keep gloved hands away from face, hair, clothing,
telephones, pt records, clinicians stool etc
Immediately remove torn gloves, wash hands
thoroughly and don new gloves
Wash hands promptly after glove removal
124

125. Full mouth disinfection should be done.
It was introduced by Leuven et al in 1990.
should be completed in 2 appointments in 24 hrs
Scaling and root planing
Tongue is brushed with chlorhexidiene gel (1%) for 1
minute
The mouth is rinsed with chlorhexidiene
solution(0.2%) for 2 minutes
Periodontal pockets irrigated with chlorhexidiene
solution(1%)
125

126. 126

127. Procedures for clinical use :
Flush all water lines at least 2 min at the beginning
of each day.
Run water through water syringes for 30 seconds
before and after 30 seconds after each patient
appointment.
127

128. 128

129. Significant exposure
Premucosal stick or wound with needle or sharp
instrument.
Contamination of any obviously open wound
with blood or saliva.
Exposure of patient’s body fluid to unbroken skin.
129

130. Procedure following Exposure
Immediately wash the wound.
The wound should be encouraged to bleed as
copiously as possible.
If the patient has not received hepatitis B
vaccination this should be commenced
immediately.
In some cases if hepatitis B positive then hyper
immune gamma globulin is given.
Many authorities recommend the prophylactic
use of azothymidine for needle stick injuries.130

131. WHO classified waste as :
1.General non hazardous
2.Sharp
3.Chemical and pharmaceutical
4.Infectious
5.Other hazardous medical waste
131

132. 132
Colour Types of waste
Red Dressings, gloves & other contaminated Dressings, gloves & other contaminated
materialmaterial
Yellow Anatomical parts & lab waste, Anatomical parts & lab waste,
biotechnology, microbiological waste, biotechnology, microbiological waste,
blood , body fluids , bandages, soiled linenblood , body fluids , bandages, soiled linen
Blue Plastics, turbings, catheters, iv sets, syringes Plastics, turbings, catheters, iv sets, syringes
without needleswithout needles
white Glass bottles and vialsGlass bottles and vials
Red can Needles , scalpels, surgical instrumentsNeedles , scalpels, surgical instruments

133. 133

134. Osha Regulation
1.Employers must provide HB immunization to employees
without charge within 10 days of employment.
2. Employers must require that universal precautions be
observed
3. Employers must implement engineering skills to reduce
production of contaminated spatter, aerosols
4.Employers must implement work practice control
precaution to minimise splashing spatter or contact of
bare hands with contaminated surfaces
5. Employers must provide facilities and instruments for
washing hands, removing gloves and washing other skin
surfaces as soon as possible after contact with blood
134

135. 6. Employers must prescribe safe handling of needles and
other sharps
7.Employers must prescribe disposal of single use needles,
vials and carpules
8.Contaminated reusables must not be stored or processed in
a manner that requires employees to reach hands into
containers to retrieve them
9.Employers must prohibit eating, drinking in the operatory or
clean up area.
10.Place blood and contaminated specimen into suitable
containers
135

136. 11. At no cost to employees, employers must provide
personal protective equipment
12.Contaminated equipment that requires service must first
be decontaminated
13. Contaminated sharps and regulated wastes should be
discarded in hard walled containers
14.Employers must provide laundering of protective
garments
136

137. Text book of microbiology – Ananthnarayana &
Paniker – 7
th
edition
Medical microbiology – greenwood
Clinical practices of dental hygenist – Wilkins – 9
th

edition
Contemporary oral and maxillofacial surgery –
Peterson – 2
nd
edition
Text book of oral and maxillofacial surgery –
Gustav O. Kruger -6
th
edition
137