A term that referring to any process that eliminates or kills all forms of life and other biological agents including transmissible agents ( such as fungi, bacteria ,virus, spore forms, unicellular eukaryotic organisms such as plasmodium etc. ) present in a specified region such as a surface , a volume of fluid , medication or in a compound such as biological culture media.

1. Sterilization
&
Disinfection
r
Made by : Dr . Utsav Gandhi Guided by : Dr . Bhavin Patel

2. Agenda
• Introduction
• History
• Terminologies
• Classification
• Details of individual agents
• Sterilization in dentistry
• Sterilization in periodontics
• Sterilization failure
• Indicator strips
• Waste management
• Recent advances
• Conclusion
• References

3. INTRODUCTION
• Pathogenic organisms cause contamination, infection , decay , So it
becomes necessary to remove and destroy them from materials and areas.
• Disinfection and sterilization are essential for ensuring that medical and
surgical instruments do not transmit infectious pathogens to patients and
staff.

4. History
- 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 milk of
tubercle bacilli.
- JOSEPH LISTER, applied Pasteur work and introduced antiseptic technique
in surgery (1867). He is the father of antiseptic surgery.

5. STERILIZATION
• A term that referring to any process that
eliminates or kills all forms of life and
other biological agents including
transmissible agents ( such as fungi,
bacteria ,virus, spore forms, unicellular
eukaryotic organisms such as plasmodium
etc. ) present in a specified region such as
a surface , a volume of fluid , medication
or in a compound such as biological
culture media.
( WHO Glossary )

6. DISINFECTION
• Destruction of pathogenic and other
kinds of microorganisms by physical or
chemical means. Disinfection is less
lethal than sterilization because it
destroys the majority of recognized
pathogenic microorganisms, but not
necessarily all microbial forms ( e.g.
bacterial spores ).
( CDC guidelines )

8. Classification of instruments to be sterilized /
disinfected
SPAULDING CLASSIFICATION
SPAULDING CLASSIFICATION
CRITICAL
NON
CRITICAL
SEMI
CRITICAL

9. CRITICAL
• Surgical and other instruments that
touches bone or penetrate soft
tissues are known as critical
instruments .
• Should be sterile after each use.

10. SEMI CRITICAL
• Instruments that touches mucous
membranes , but do not touch bone or
penetrate soft tissue.
• If the sterilization is not feasible because
the instruments will be damaged by
heat , use high-level disinfection (HLD).

11. NON CRITICAL
Instruments that
contact intact skin and use
intermediate-level or low-
level disinfection for them.

12. THREE LEVELS OF DISINFECTION

14. METHODS
PHYSICAL CHEMICAL
PHYSIO-
CHEMICAL
Sunlight Alcohol
Dry heat Aldehydes
Moist heat Dyes
Filtration Halogens
Radiation Phenols
Ultrasonic and sonic Surface active agents
vibrations Metallic salts
GASES :
Formaldehyde
Ethylene oxide
Plasma

15. PHYSICAL AGENTS
SUNLIGHT
Active germicidal effect due to heat and UV rays
Seen in tanks , rivers , lake .
HEAT
DRY HEAT
MOIST
HEAT
Thermal death time-
Minimum time required to kill a suspension of
organisms at a predetermined temperature in a specified
environment

16. DRY HEAT
Flaming:
e.g. scalpels, mouth oftest tubes, flasks,
glass slides and cover.

17. • INCINERATION :
Method of destroying
contaminated material by burning
them in incinerator .
e.g. soiled dressings; animal
carcasses, pathological material,
bedding .

18. DRY HEAT
• PRINCIPLES :
Protein denaturation
Oxidative damage
Toxic effects of elevated levels of electrolytes .

19. HOT AIR OVEN
• Most widely used method of sterilization.
Uses :
- Glassware like glass syringe,
Pipettes , flasks , test tubes.
- Surgical instruments like scalpels,
scissors , forceps .
- Chemicals like liquid paraffin ,
fats , sulphonamides , dusting
powder etc.

20. MOIST HEAT STERILIZATION
Temperature
below 100o C C
Temperature at
100o C C
Temperature
above 100o C C
Pasteurization of milk
Inspissation
Vaccine bath
Serum bath
Boiling
Tyndallisation
Steam sterilizer
Autoclave

21. Vaccine bath :
- Serum or body fluid is sterilized in water bath
At 56o C for 1 hour.
-Vaccines are sterilized at 60o C for 1 hour .
Serum bath :
-The contaminating bacteria in a serum preparation
can be inactivated by heating in a water bath at
56o C for 1 hour .

22. Pasteurization of milk :
by Louis Pasteur .
- Employed in food and dairy industry .
- There are 3 methods :
1) Holder method - heated at 63o C for 30 minutes .
2) Flash method - heated at 72o C for 15 seconds
followed by quickly cooling to 13o C .
3) Ultra pasteurization – heated at 82o C for 4 sec
followed by cooling to 4o C .

23. Boiling :
Boiling water (100o C) for 10–30 minutes kills most vegetative bacteria and
viruses.
- Metal articles and glassware disinfected by placing them in boiling water for
10-20 minutes.
- The lid of the boiler must not be opened during the period
- Syringes, forceps, scissors etc.
Tyndallisation :
Steaming at 100°C is done in steam sterilizer for 20 minutes
followed by incubation at 37°C overnight.
Repeated for another 2 successive days.

24. AUTOCLAVE
It kills all the vegetative as well as spore forms of bacteria .
Three major factors :
1.Temperature : 121o C
2. Pressure : 15 psi
3.Time : 15 min
temperature and pressure = time for sterilization

25. Autoclave

26. Boiling water alone is insufficient to kill spores & viruses
water boils when its vapor pressure equals to that of surrounding
atmosphere
so, when pressure increases inside closed vessel
temperature increases at which water boils
Saturated steam has penetrative power
when steam comes in contact with a cooler surface
it condenses to water
and gives up latent heat to surface
The large reduction in volume of steam sucks in more steam to the site &
process continues till temperature of article is raised to that of steam.

27. Pressure( psi ) Temperature
(o C )
Time ( min )
15 121 15
20 126 10
20 134 3

28. CLASSIFICATION OF AUTOCLAVE

29. ADVANTAGES DISADVANTAGES
- Economical
- Good penetration
- Short cycle time
- Early monitored
- No special chemicals
required
- Moisture retention
- Corrosion
- Carbon steel gets
damaged
- Dulling of unprotected
edges
- Destruction of heat
sensitive materials

30. FILTRATION
• Filtration is the preferred method of sterilizing heat-sensitive liquid and gases without exposure to
denaturing heat. Rather than destroying contaminating microorganisms, it simply removes them.
Candle filter

31. Membrane filtration

32. Asbestos
filtration
Sintered Filtration

33. Radiation
Ionizing
radiation
Non-ionizing
radiation
Gamma rays or x-rays
Also known as “Cold sterilization”
Infrared radiation
UV rays

34. Non-Ionizing
radiation
Ionizing
radiation
- Longer wavelength &
lower energy
So, low ability to penetrate
any substances so used only
for sterilizing surfaces.
- Shorter wavelength &
High energy
So, high penetrative power
to destroy microorganisms.

35. Infrared radiation – Rapid mass sterilization of catheters ,
syringes .
UV rays – For disinfection of operation theatres , laboratories
like closed areas.
Cold sterilization - No major increase in temperature.
- Used for sterilizing plastics , metal foils ,
swab.

36. Gamma radiation
• Most popular method .
• Highly penetrative and can kill contaminating microorganisms.
• Low dose rates .
• Gamma radiation kills microorganisms by attacking on their DNA
molecule- this is known as Substantial decrease in organism survival .
• Advantages – Rapid processing , uniform dose distribution,
Precise dosing , dosimetric release .
Used as penetrating sterilant even with high density products .

38. E-beam : electron beam radiation - High energy electrons capable of
inducing biological damage are
generated by electron beam
accelerators.
- Electron energies of ~10 MeV are used in most cases.
- The penetration ability of electrons is lower than that of gamma rays, So e-beam
sterilization is limited in application to lower density or smaller products. However, e-
beam sterilization can use higher dosages and shorter treatment times (seconds vs.
min/hours) .
X-rays radiation- X-rays are produced when high energy electrons from the
accelerator interact with high atomic number nuclei, such as
atoms of tungsten or tantalum. In a process known as Bremsstrahlung,
the deceleration of the electron when passing the nucleus results in the
release of X-rays. Electron energies of 5-7 MeV are commercially used
X-rays used for sterilization can be more penetrating than either gamma-rays or
electron beams.
( Radiation sterilization from Stanford university , march 2018 )

39. Ref. -This data is shared by
Stanford university in march,2018

40. FUMIGATION – Asepsis of surgical theatre
ELECTRIC BOILER
METHOD
POTASSIUM
PERMANGANATE

41. 2). POTASSIUM
PERMANGANATE :
Heat is induced by potassium
permanganate .
500 ml of formaldehyde added to
it which reacts and generates
fumes.
1). ELECTRIC BOILER
METHOD :
500 ml of formaldehyde added to
distilled water in electric boiler .
When the water heats , fumes are
generated .

43. Asepsis in operatory surfaces
• Operatory surfaces that are touched or soiled
repeatedly are best protected with disposable
covers that can be discarded after each treatment.
• For dental unit , Paper , plastic film or surgical pack
wraps should cover the entire tray.
• GIGASEPT : Used for disinfection of plastic and
rubber materials . e.g. Dental chair .
GIGASEPT contains - Succindialdehyde +
dimethoxytetrahydrofuran

44. CHEMICAL METHODS
• ALCOHOL :
- 70 % ETHYL ALCOHOL
Suitable for skin preparation before venepuncture.
- Isopropyl alcohol .
Used as a
skin
disinfectant
Active
against
fungal
spores

45. ALDEHYDES
• Formaldehyde , Glutaraldehyde .
• Bactericidal, sporicidal, and also effective against viruses
• They are chemical sterilants .
• For surface disinfection and fumigation
• 10% formalin with 0.5% tetraborate sterilizes
clean metal instruments.
40% formaldehyde

46. To disinfect hospital and laboratory equipment .
An exposure of at least 3 hours at alkaline pH is required for action by
glutaraldehyde.
Especially effective against tubercle bacilli, fungi, and viruses
2% Glutaraldehyde
CIDEX ( 2% NaHCO3 /
B.GLUTARALDEHYDE)

47. PHENOLS
• MOA : Act by disruption of membranes,
precipitation of proteins and
inactivation of enzymes .
5% phenol , 5% Lysol , 1-5% cresol ( Lysol )
chlorhexidine ( Savlon ),chloroxylenol ( Dettol )
• As disinfectants at high concentration and as
antiseptics at low concentrations .
• Bactericidal, fungicidal, but are inactive against
spores and most viruses .

48. HALOGENS
CHLORINE
COMPOUNDS
IODINE &
IODOPHORES
Mostly used disinfectant for
HIV infected materials.
Concentration – 0.05% or
0.5%
Useful for skin preparation ,
mouthwash and as a surgical
scrub.
7.5% povidone + iodine =
Betadine

49. SURFACE ACTIVE AGENTS :
MOA : Disrupt membrane resulting in leakage of cell constituents
Examples:
- Soaps or detergents, anionic or cationic
- Anionic detergents- soaps and bile salts .
- Cationic detergents are known as quaternary ammonium compounds.
- Cetrimide and benzalkonium chloride act as cationic detergents .
SALTS :
-Salts of copper , silver , mercury are used as a disinfectant .

50. LOWTEMPERATURE H2O2 PLASMA
(Sterrad)
• Active medium – H2O2 plasma
• Plasma is an ionized gas made up of electrons.
• Temp. – 45-50 c
• Sterilization time – 45-70 minutes .
• 2 stages : Air from sterilization chamber is removed & vacuum is created.
after that , H2O2 is injected & vaporized in chamber
It diffuses in chamber & come in contact with surface of various items
where it kills bacteria.

51. Then ,
radiofrequency energy is applied in chamber that
creates electric field
Form a low temperature plasma
It causes ionization of H2O2 molecules & creates
free radicals which kills microorganisms.

52. Plasma

53. PLASMA

55. ETHYLENE OXIDE
Highly inflammable
• Used as 10% CO2 + 90% EO or
Dichlorodifluoromethane.
• Used to sterilize heat or moisture sensitive.
• Kills microorganisms including spores , but
sterilization time is longer than 16-18 hours
for complete cycle.
• Temperature around 50-60 c because it is
highly inflammable , so used in explosion
proof sterilizing chamber .

57. Steris system 1
• Another low temp. sterilization system that uses
a peracetic acid solution (Steris20TM solution ) –
to destroy dangerous microorganisms .
• Temp. = 50-56 c
• Sterilisation cycle completed in 12 min , followed
by repetitive sterile rinses .
• Total sterilization process is completed in 30 min .
• The bactericidal action of peracetic acid is
because of presence of extra oxygen atom
attached to acetic acid .

58. Flash sterilization
- Sterilization of an unwrapped object at 132 C
for 3 min at 27-28 lbs of pressure in a gravity
displacement sterilizer.
( defined by Underwood & Perkins )
Uses :
- For processing cleaned patient cared items
that cannot be packaged , sterilized or stored
before use.
- It is also used when insufficient time to sterilize
an item by the preferred method.

59. Sterilization in periodontal clinic
All diagnostic instruments are sterilized by washing in korsolex and sterilised.
Periodontal instruments :
SHARP : Knives , scissors , files , tissue holding forceps
Sterilised by Conventional hot air oven.
BLUNT : Mouth mirrors , tweezers , artery forceps , suture holding forceps ,
periosteal elevator
Sterilised by autoclave .

60. Sutures
• Sutures are pre-sterilised by gamma
radiation.
• They are re-sterilised by two methods :
1).Soak for 10 minutes in completely
immersed in 10% povidone iodine
solution then rinse in sterile
saline/water .
2).Ethylene oxide – Gas sterilization

61. ULTRASONIC SCALERS
Ethylene oxide – best method
Soak in a container that contains 70% isopropyl alcohol – for removal of
organic debris
Rinse clean inserts in warm water to remove all chemicals
Then, replace the insert into scaler handpiece & operate for 10 seconds at
maximum water flow setting to flush out any retained chemicals
Dry insets completely with air syringe
Package in proper wrap , bags , pouches , trays .

62. Recent advances
ULRAVIOLET
LIGHT
OZONE
PEROXIDEVAPOR

63. Peroxide vapor
sterilization
Ultraviolet light

64. OZONE
• A low temperature sterilization method.
• Used for heat sensitive & moisture sensitive
devices.
• Cycle time : At temperature of at 85o F - 94o F for
4.5 hours

65. • Conclusion :
The results showed that the ozone may be considered as
effective and promising alternative for sterilization of thermosensitive
materials and medical devices.

66. Sterilization pouch
• Also known as “Peel pack” .
• A disposable package used in a sterilizer to allow the penetration of the
sterilant to the items placed inside .
• Three designs Self - seal
Heat-seal
Rolls or tubing
Paper / plastic Two types
Tyvek / plastic
Ref : Steris healthcare

67. Self sealing sterilization pouch

69. SAL
• Sterilization is the process of removal or inactivation of all
microorganisms present on the surface to achieve an
acceptable sterility assurance level (SAL). A SAL of 10−6 is considered
the standard for medical devices and defines the probability of 1 in
1000000 that a device is not sterile . The most common sterilant are
highly potent agents developed to inactivate all microbiological
species.

71. Published in GMS Krankenhhyg Interdiszip. 2008

72. Sterilization failure
• Causes :
- Improper cleaning of instruments
- Improper packing
- Improper temperature in sterilizer
- Improper loading of sterilizer
- Improper timing of sterilization cycle

73. •Steps to be taken after sterilization failure :
- 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

74. UNIVERSAL PRECAUTIONS
• DEFINITION :
Measures design to prevent transmission of disease from blood spillage and
body fluids .
( CDC guidelines )
• Precautions :
Airborne
Droplet
Contact

75. • Transmission of disease :
A germ
A source
An exit
Method of sterilization
Portal of entry
A susceptible person
The goal is to stop germs from travelling from source to another person .

76. Considered Highly
infectious
Not infectious unless contaminated
Blood Faces
Semen Nasal secretion
Vaginal secretion Sputum
CSF Tears
Synovial fluid Urine /Vomit
Amniotic fluid Saliva

78. When to wash hands
• Before and after contact with patients.
• Before and after gloving
• BeforeTaking care of immune suppressed new born
• Use Non medicated soap and water
• In demanding circumstances , use ethyl or isopropyl alcohol .

79. Gloves
• Do not reuse the gloves .
• Change after the contact with each patient.
• Do not touch other environmental surfaces.
• Do not touch the face with contaminated
gloves.
• Discard it properly .

80. Masks , Caps , Eyewear
• Should wear a mask while operating the
patient and if you have a condition that is
transmissible cough .
• Use caps to protect your hairs
• Use eyewear to shield against splashing body
fluids .

81. • Use protective shoes and no open ties .
• Use an apron or gown :
Prevent exposure to harmful germs and
environment.
Prevent our clothes from contamination .

82. Use of needles
• Use properly and wear the gloves.
• Dispose in thick puncture resistant container.
• Avoid recapping the needles.
• Use disposable needle and syringes .

83. Instrument processing
As per ADA
guidelines

86. Waste Management
Options Waste Category
Category 1 Human Anatomical wastes
(tissues, organs, body
parts)
Category 2 Animal wastes
Category 3 Microbiology and
biotechnology wastes
Category 4 Waste sharps ( needles
syringe , scalpels )
Category 5 Discarded medicine and
cytotoxic drugs

87. Options Waste Management
Category 6 Solid waste ( items contaminated with
blood and fluid including cotton dressing
…)
Category 7 Solid waste ( waste generated from
disposable items )
Category 8 Liquid wastes ( waste generated from
laboratory and washing cleaning…)
Category 9 Incineration ash
Category 10 Chemicals used in production of biological,
chemical used in disinfection

88. COLOUR CODING

90. PPE
• Personal protective equipment, commonly referred to as "PPE", is equipment
worn to minimize exposure to hazards that cause serious workplace injuries
and illnesses. These injuries and illnesses may result from contact with
chemical, radiological, physical, electrical, mechanical, or other workplace
hazards.

91. PPE kit

92. • PPE protects healthcare workers from two main hazards:
Radiation (Enhancing radiation safety in health care)
Biological agents (virus, bacteria, etc.)
Important transmission pathways to mitigate with PPE include:
• Person to person contact
• Droplet spread
• Airborne transmission
• Contaminated objects

98. Indicator strips for every autoclave and
sterilizer
•Chemical Indicator strips
Each CI product visually verifies that items have seen the
sterilization process and should be used in conjunction with
routine “spore testing" as part of an overall sterility assurance
program.

99. Dry heat indicator strips –
DIS - 100
Steam Indicator strips
SIS - 100

100. Biological Indicators
• A standardized preparation of bacterial spores on or in a carrier serving to
demonstrate whether sterilizing conditions have been met .
• Each BI contains live Bacillus spores which document their death that
sterilization was actually achieved .
• An in office BI system for use with steam, EO gas , chemical vapor , dry heat.
• After processing in a normal load , the user aseptically transfer BI strip into
media & incubates at 56 Celsius ( Steam/ C . vapor ) or 37 Celsius ( EO gas /
dry heat ) for 7 days .
• A colour change and visible turbidity of a processed BI indicates sterilization
failure .

101. SporeView Culture Set –
CS-100
SporeView Culture Set 56 C
( Stater kit SK056
comes with indicator )

102. SporeView Culture Set 37 C
( Stater kit SK037
Comes with incubator )
Biological indicator strips
DS-100

103. Immediate read out system
• This advanced technology medical device is Scientifically engineered to integrate all
3 critical parameters of sterilization (time, temperature and saturated steam), the
SteamPlus Sterilization Integrator is certified to perform equal to a biological
indicator plus an added safety factor.
SteamPlus integrator – SSI 100

104. From
chemosphere
journal

106. From Indian
journal of critical
care medicine

107. Conclusion
• Dental health care providers have to follow high standards of infection
control for safety of patients , dentists & staffs .
• An increase in cases of some serious transmissible diseases over last few
years became a global concern and we have to take care about it by
preventing the transmission of it .

109. References
• WHO Glossary
• Periobasics - A textbook of periodontics & Implantology 2nd edition , Nitin Saroch
• Textbook of clinical Periodontology , Newman , Carranza 13th edition
• Operative dentistry , Studervant , Chapter – inf control
• Textbook of Microbiology , By CP Baveja , 3rd edition
• CDC guidelines for sterilization & disinfection
• CDC guidelines for health care facilities
• Sterilization & disinfection By ADA
• Articles on sterilization & disinfection on periodontal instruments by Robert B.
Parks & Robert A. Kolstadf

110. THANK YOU