contents: Introduction; Historical Background; Definitions; Factors That Influence Degree Of Sterilization; Classification of Instruments; Instrument washer; Thermal disinfectors; Objectives; How sterilization works; New methods of sterilization; New methods of sterilization; Monitors of sterilization; Dental radiology asepsis; Laboratory asepsis; Precautions by operator; Disposal of waste; Osha standards; Handpiece sterilization; Ultrasonic scalars asepsis; GTR membranes, Implants, Bone Grafts presterilization ; Conclusion; References.

1. STERILIZATION AND
DISINFECTION
• K.P.YASASWINI IST YEAR PG
• GUIDED BY: DR. P.VEERENDRANATH REDDY

2. CONTENTS:
Introduction;
Historical Background;
Definitions;
Factors That Influence Degree Of Sterilization;
Classification of Instruments;
Instrument washer;
Thermal disinfectors;
Objectives;
How sterilization works;
New methods of sterilization;

3. New methods of sterilization;
Monitors of sterilization;
Dental radiology asepsis;
Laboratory asepsis;
Precautions by operator;
Disposal of waste;
Osha standards;
Handpiece sterilization;
Ultrasonic scalars asepsis;
GTR membranes, Implants, Bone Grafts presterilization ;
Conclusion;
References.

4. INTRODUCTION
Microorganisms are ubiquitous.
Since pathogenic microorganisms cause contamination, infection
and decay, it becomes necessary to remove or destroy them from
materials and areas.
This is the objective of infection control and sterilization.

5. HISTORICAL BACKGROUND
More Than 100 Years Ago, SEMMELWEIS Demonstrated That
Routine Hand Washing Can Prevent The Spread Of Disease.

6. Hippocrates of cos (460-377 BC), was the
first to separate medicine from philosophy
and disproved the idea that disease was
punishment for sin. He also advocated
irrigation of wounds with wine or boiled
water, foreshadowing asepsis.
In 1862, French chemist and microbiologist
Louis pasteur publishes his findings on how
germs cause disease, which he later uses to
develop the pasteurization process.

7. Joseph Lister, an English
physician, reduced the mortality
rate of his patients in 1867 by
using a carbolic solution spray as
he operated, he then used it in the
wound.
 Charles Chamberland, Louis
Pasteur developed the first
pressure steam sterilizer, or
autoclave in 1879.

8. The research of Robert Koch and his associates in 1881 on the
disinfecting properties of steam and hot air mark the beginning of
the science of disinfection and sterilization. They devised the first
Non Pressure Flowing Steam Sterilizer.
Aesculap created the first rigid instrument container, originally
made of stainless steel, in Germany. In the early 1900’s,
responding to the needs of the military hospitals and aid stations,
Aesculap manufactured chrome-plated containers for safe
transport of sterile instruments.
All these together with further developments contributed to the
present methods of sterilization.

9. DEFINITIONS
STERILIZATION: the process by which an article, surface or
medium is freed of all living microorganisms either in the
vegetative or spore state.
DISINFECTION: Means destruction of all pathogenic
microorganisms, or organisms capable of giving raise to
infection ,but not necessarily their spore forms.

11. Sepsis : refers to presence of infection, infectious material or
agent.
Asepsis: freedom from infection, prevention of contact from
pathogens.
Infection: invasion of the body tissues by the pathogenic
bacteria.
Infection control: Also called “exposure control plan”, is a
required office program that is designed to protect personnel
against risks of exposure to infection.

12. FACTORS THAT INFLUENCE THE DEGREE OF
STERILIZATION
Types Of Organisms;
Number Of Organisms;
Concentration Of Disinfecting Agent;
Presence Of Organic Material (Eg., Serum, Blood);
Nature (Composition) Of Surface To Be Disinfected;
Contact Time;
Temperature;
PH;
Biofilms;
Compatibility Of Disinfectants And Sterilants.

13. Type of organisms: organisms vary in their ability to withstand
chemical and physical treatment. Eg.,spores – have coats rich in
proteins, lipids and carbohydrates. so need higher temperature to
get killed.
Number of organisms: sterilization depends on organisms
present with varying degrees of susceptibility to killing agents.
1. Not all organisms die at the same time ;
2. Higher numbers of organisms usually require longer
exposure of sterilization.

14. Concentration of disinfecting agent: proper concentration of
disinfecting agents ensure the activation of target
organisms.Eg.,povidone-iodine should be diluted with water
before use because there is no enough free iodine to kill
microorganisms in concentrated solution.
Presence of organic material (e.g., serum, blood): presence of
organic material (such as blood, mucus, pus) affects killing
activity by inactivating the disinfecting agent and also forms
coating which prevents direct contact between instrument and
disinfectant.

15. Nature (composition) of surface to be disinfected: Some
medical instruments are manufactured of biomaterials that
exclude the use of certain sterilization methods because of
possible damage. Eg:- Endoscopic instruments cannot be
sterilized by the heat in an autoclave.
Contact time: The amount of time a disinfectant is in contact
with the object is critical Eg:-Betadine (alcohol and iodine) must
be in contact with object for at least 1 to 2 min. To kill
microorganisms.
Biofims: Biofilms are communities of microorganisms ,which
can easily survive on a surface of inanimate objects, Eg:-
Catheters (critical place), pipes that carry water, make
disinfection more difficult. So, the concentration of the
disinfectant need to be increased in such cases.

16. Temperature: Disinfectants are generally used at room
temperature but their activity is increased by an increased
temperature and decreased by a drop in temperature.
Compatibility of disinfectants and sterilants: common mistake
is to believe that two disinfectants are better than one. But fact is,
some of them may inactivate each other. Eg:-The bleach and
quaternary ammonium compound used together, results in less
degree of sterilization.

18. Critical:-
• Penetrate or touch broken skin or mucous membranes.
• Needles, scalpels, surgical instruments, mirrors, dental
explorers.

19. SEMICRITICAL:-
• Touch intact mucous membranes.
• Amalgam condensers, handpieces, ultrasonic cleaners.

20. Non critical:-
• That do not touch mucous membranes.
• Counter tops, light handles, chair surfaces.

21. PROCEDURES FOR HANDLING
AND CLEANING INSTRUMENTS
BEFORE STERILIZATION

22. ULTRASONIC
CLEANERS:
More effective than manual cleaning;
Placing instruments in an ultrasonic cleaner is
the most common method used by dental
teams to clean instruments prior to
sterilization.
The ultrasonic activity — also known as
cavitation — combined with detergent
solutions, removes blood, saliva, and other
debris from instruments.

23.  Use only cleaning solutions recommended
by ultrasonic device manufacturers.
Operate the ultrasonic cleaner for 3-6
minutes or longer as directed by the
manufacturer.
The most recent developments in ultrasonic
cleaning solutions have been the addition of
enzymes to boost the cleaning properties of
the solutions.
The enzymes act as catalysts to break down
organic materials, such as blood and saliva.

24. INSTRUMENT WASHER
Instrument washers use high-velocity hot water and a detergent
to clean instruments.
These devices require personnel to either place instruments in a
basket or to use instrument cassettes during the cleaning and
drying cycles.

25. THERMAL DISINFECTORS
These devices may look like the instrument washers; however,
there is one important difference.
The high temperature of the water and chemical additives in
these devices cleans and disinfects the instruments.
Instruments can be more effectively cleaned.

26. OBJECTIVES
Reduction of available pathogenic micro-organisms.
Elimination of cross contamination by breaking the
chain of infection.
Application of standard precautions.

27. HOW STERILIZATION WORKS
Disruption of
cell wall can
not prevent
cell from
bursting due
to osmotic
effects.
Damage to
cytoplasmic
membrane
causes cellular
contents to leak
out.
Damage to
viral
envelope
interrupts
viral
replication.

29. PHYSICAL METHODS
SUNLIGHT:
• Natural method of sterilization in cases of water in tanks, lakes
etc.
• Active germicidal effect due to UV rays.

30. HEAT
Two types:
1.Dry heat :(kills organisms by denaturation of protein, oxidative
damage to cell walls);
2.Moist heat :(kills organisms by coagulation of proteins).

31. DRY HEAT STERILIZATION
Includes
• Red heat- inoculating wires or loops, held
in flame of bunsen burner until they turn
red hot.
• Flaming –glass slides and mouth of culture
tubes are passed onto flame.
• Incineration: infective material such as
dressings, anatomical wastes etc are
reduced to ashes by burning in instrument
called incinerator.

32. HOT AIR OVEN
Most widely used method by dry heat;
Procedure:
• Oven is electrically heated and is fitted with a fan to ensure
adequate distribution of hot air;
• Fitted with thermostat that maintains chamber air at chosen
temperature;
• 160°C for one hour.

33. Time –temperature combinations:
Temperature holding time
160°c 120 min
170° c 60 min
180° c 30 min
150° c 150 min
Monitoring
Quality control to check whether the equipment is working
properly .
1. Chemical controls: Browne's tubes color from red to
green.
2. Biological controls: Paper strips containing spores of
clostridium tetani, and Bacillus atrophaeus.

34. Uses:
• Glass wares like pipettes, Petridishes, flasks and test tubes;
• Chemicals like liquid paraffin, Sulphonamide powders.
 Precautions:
• Not to be overloaded;
• Allow free circulation of air;
• Rubber materials or inflammable materials should not be kept;
• Allowed to cool for 2hrs as sudden cooling leads to cracking of
glasswares.

35. Advantages of dry heat sterilization:
1. Carbon steel instruments and burs do not rust, corrode, if they
are well dried before processing.
2. Low initial cost and sterilization is verifiable.
Disadvantages of dry heat sterilization:
1. High temperatures may damage more heat-sensitive items, such
as- rubber or plastic goods.
2. Longer time compared to other methods;
3. Not effective as moist heat in penetration.

36. MOIST HEAT STERILIZATION
• TYPES OF MOIST HEAT STERILIZATION:
Temp. below
100 °C
Temp. /steam at
100 °C
Saturated steam
Temp. above 100 °C
Pasteurization;
Inspissation;
Vaccine bath.
Boiling;
Tyndallization;
Koch steam sterilizer.
Autoclave.

37. PASTEURIZATION
Used to kill bacteria from raw milk
Methods :-
•Holder method—heating at 63°c for 30 min.
And cooled rapidly to 4°c.
•Flash method—heating at 72°c for 20 seconds
and rapidly cooled to 4°c.
Ultra pasteurization-82c for 3 sec.

38. INSPISSATION
• It is the process of sterilization in fractional method;
• Media such as Lowenstein –Jensen media and Loeffler’s serum
are rendered sterile by heating at 80-85 C for half an hour on
three consecutive days.

39. VACCINE BATH
Bacterial vaccines are sterilised in special vaccine baths at 60℃
for one hour.
Viruses- polioviruses & hepatitis B at 60̊ C for 30 min and 1hr
respectively.

40. TEMPERATURE AT 100C
BOILING:
• Material is immersed for 10 – 30 min at atmospheric pressure, at
100 C;
• Vegetative bacteria are killed but not spore forms.
Advantages:
• Inexpensive method ;
• Easy to handle.
Disadvantages:
• Sporing bacteria not killed;
• Not recommended for surgical instruments.

41. TYNDALLISATION
100 °C for 20mins on three successive days;
The first exposure kills all vegetative bacteria ;
Spores are in a favourable medium will germinate and be killed
on subsequent heating;
Used for egg or serum containing media which are not
damaged at higher temperature of autoclave.

42. KOCH STEAM STERILIZER
Used to sterilize culture media which may decompose when
exposed to higher temperature
100 C for 90mins
Advantages:
Simple method
Requires little attention

43. TEMPERATURE ABOVE 100C
Autoclave:
• The autoclave was invented by charles chamberland in 1879.

44. DEFINITION
Autoclave is a pressurized device designed to heat aqueous
solutions above their boiling point at normal atmospheric
pressure to achieve sterilization.

45. Autoclaving is the preferred method of sterilization unless the
material to be sterilized can be damaged by heat or moisture.
121 c ;15 lbs pressure for 15mins;
126 c; 20 lbs pressure for 10mins;
134 C; 30 lbs pressure for 3 mins.

46. STEAM PRESSURE
STERILIZATION (AUTOCLAVING)
• It is very important to ensure that all of the trapped air is
removed from the autoclave before activation, as trapped air is a
very poor medium to achieve sterilization.

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

48. Types of autoclave:
1.DOWNWARD DISPLACEMENT:
A. Also known as gravity displacement unit.
B. This is because of the method of air removal in the sterilization
chamber.
2.VACUUM TYPE: A vacuum pump is present in the chamber,
which sucks air from the chamber.

49. • TRIPLE VACUUM AUTOCLAVE: Type of vacuum pump type
autoclave;
• This is repeated three times, hence the name “Triple vacuum"
autoclave. This type of autoclave is suitable for all types of
instruments and is very versatile.

50. CLASSIFICATION OF AUTOCLAVE
classification Suitable for processing Used by
N Type (Downward
Displacement)
Unwrapped solid
instruments for immediate use.
S Type (Vacuum)
Items specified by the
autoclave manufacturer.
single wrapped solid and
hollow items.
Medical Surgeries,
Tattooist,
B Type (Vacuum)
Unwrapped & wrapped
solid and hollow
instruments. Porous loads,
e.g drapes

51. Considerations during autoclaving ;
1.Ensure complete air removal for temperature to reach 121°C.
2. Ensure loose packing in the chamber.
3. Tightly sealed materials may become dangerously pressurized
causing injury when removed.
Uses: Disposable syringes, non disposable syringes, glassware,
metal instruments, surgical dressing, surgical instruments,
laboratory equipment, culture media, pharmaceutical products.

52. ADVANTAGE:-
Economical;
Good penetration;
Short cycle time;
Easily monitored;
No special chemicals;
or exhaust required.

53. Disadvantage:-
Moisture retention;
Causes corrosion;
Carbon steel gets damaged;
Dulling of unprotected cutting edges;
Destruction of heat sensitive materials.

54. PERIODONTAL INSTRUMENTS
STERILIZED BY AUTOCLAVE
GENERAL• Periosteal elevators
• Bone files
• Artery forceps
• Needle holder
• Scissors
• Curettes
• Probes
• Hand pieces
• Greencloth
• Aprons
• Kidney trays
• Towel and towel packs

55. CHEMICAL VAPOUR PRESSURE
STERILIZATION (CHEMICLAVING)
• Similar to autoclave except combination of chemicals (alcohols
and formaldehyde)used instead of water to create vapor for
sterilization.

56. ADVANTAGES
• Carbon steel and other
corrosion-sensitive instruments
are said to be sterilized without
rust
• Low water content prevents
dulling of burs and files
• Short cycle
DISADVANTAGES
• Vapor odor is offensive, requires
aeration. So adequate ventilation
needed to remove residual
formaldehyde.
• Heavy cloth wrappings of surgical
instruments may not be penetrated
to provide sterilization.
This operates at 131C at 20 lbs pressure for
about ½ hour .

57. FLASH STERILIZATION
• Modification of conventional steam sterilization
in which the flashed item is placed in a specially
designed, rigid container to allow for rapid
penetration of steam.
• Sterilization of an unwrapped object at 1320c for
3 minutes at 27-28 lbs. Of pressure.
Uses:
• Rapid sterilization of instruments;
• Designed for the steam sterilization of patient
care items for immediate use.

58. GLASS BEAD STERILIZER
Commonly used in the endodontic practice for working ends of
endodontic files and reamers;
Place them in a container containing glass beads heated up to
225°C for 5-10secs.
Advantages:
Effective killing of microbes in short time.
Disadvantages:
Expensive
Beads less than 1mm can get stuck in between broaches or files.

59. FILTRATION
Helps to remove bacteria from heat labile liquids such as sera &
solutions of sugars or antibiotics used for preparation of culture
media
Types of filters used:
1.Candle filters:
Used for purification of water for industrial and drinking
purposes.

60. 2.SINTERED GLASS FILTERS:
• Prepared by heat fusing finely powdered glass
particles.
• Used in chemical laboratories.
3.MEMBRANE FILTERS:
• Made of cellulose esters or other polymers;
• Routinely used sterilization of solutions for
parenteral use.
Eg: blood samples etc

61. RADIATION
Two types of radiation are used for sterilization.
Non ionizing radiation :
Infrared;
UV rays ;
Wavelength longer than visible light.
Infrared : prepacked items such as syringes and catheters;
UV rays: disinfecting closed areas such as entryways, operation theaters ,
laboratories.
Ionizing radiation : usually employed are gamma rays.
High penetrating power and highly lethal to DNA;
Materials sterilized : plastics, syringes, swabs, catheters, oils, greases,
fabrics & metal foils.

62. CHEMICAL AGENTS OR COLD
STERILIZATION
Cold sterilization is a method of sterilization that requires the reusable semi-
critical items to be immersed in liquid chemicals.
An ideal antiseptic & disinfectant should:
Have wide spectrum of activity;
Active in presence of organic matter;
Be effective in presence of acidic and alkaline medium;
Have speedy action;
Have high penetrating power;
Be compatible with other antiseptics & disinfectants;
Not cause local irritation;
Not interfere with healing.

64. PRE PROCEDURAL MOUTH RINSES
Several chemical agents are employed as pre
procedural oral rinses by dentist to minimise aerosols
harmful effect.
Eg: chlorhexidine, quaternary ammonium
compounds, essential oils etc
Even povidone iodine(betadine) can be diluted and
used commonly as oral rinse.
Dilution factor is, as a mouthwash: dilute one part
of iodine with two parts of water,
For infections of mouth and throat: use full
strength and rinse or gargle for 30 seconds.

65. ETHYLENE OXIDE
STERILIZATION (ETO)
Sterilization is carried out between 30C and 60C; with a
relative humidity of 30% and a gas concentration of 200-
800mg/l and typically lasts for 3 hours.

66. Advantages:
Operates effectively at low temperatures;
Gas is extremely penetrative;
Can be used for sensitive equipment like handpieces.
Disadvantages:
 1.Potentially mutagenic and carcinogenic.
 2.Requires aeration chamber.

67. PERIODONTAL INSTRUMENTS
STERILIZED BY ETHYLENE OXIDE
GAS
• Micromotor cord;
• Air rotor cord;
• Ultrasonic cord;
• Sutures;
• Disposable material;
• Blades;
• Scalpels;
• Plastics.

68. NEW METHODS OF
STERILIZATION
Various new methods of sterilization are under investigation and
development.
Peroxide vapor sterilization - an aqueous hydrogen peroxide
solution boils in a heated vaporizer and then flows as a vapor into
a sterilization chamber containing a load of instruments at low
pressure and low temperature .

69. GAS PLASMA STERILIZATION
Plasma is a fourth state of matter which is distinguishable from
liquid, solid, or gas.
Uses gas plasma generated in an enclosed chamber under deep
vacuum using radio frequency.
The mechanism of action of this device is the production of
free radicals within a plasma field that are capable of
interacting with essential cell components, i.e., With enzymes
and nucleic acids, thereby disrupt the metabolism of
microorganisms.

70. OZONE
An emerging technology for low-temperature sterilization
involves the use of ozone.
Ozone is the most powerful oxidative agent and with its extra
free radical oxygen molecule, ozone is able to destroy microbes.
Ozone parameters:
 • The cycle time is approximately 4.5 hours, at a temperature of
850F – 940F.
 Advantages:
 Suitable for many heat sensitive and moisture sensitive or
moisture stable medical devices;
The cost of sterilizing with ozone is much less than ethylene
oxide gas.

71. MONITORS OF STERILIZATION
THERE ARE 3 METHODS OF MONITORING
STERILIZATION:
• BIOLOGICAL INDICATORS –USING SPORES;
• MECHANICAL TECHNIQUES-USING
THERMOCOUPLES;
• CHEMICAL INDICATORS – USING STRIPS.

72. BIOLOGICAL CONTROLS FOR DIFFERENT
STERILIZATION METHODS
METHOD OF
STERILIZATION
Hot Air Oven
Bacillus subtilis subsp. Niger
Clostridium tetani
Autoclave Bacillus stearothermophilus
Filtration
Serratia marcescens,
Pseudomonas diminuta
Ionizing Radiation Bacillus pumilis 2
BIOLOGICAL CONTROL

73. EFFECT OF STERILIZATION ON
INSTRUMENTS

75. THERMOCOUPLES
A thermocouple is a sensor used to measure
temperature.
Thermocouples consist of two wire legs
made from different metals.
 The wires legs are welded together at one
end, creating a junction. This junction is
where the temperature is measured.
Copper wires coated with teflon are most
commonly used type.

76. CHEMICAL STRIPS
• TST strips indicators undergo a chemical change (from yellow
to dark blue) when exposed to proper time – steam –
temperature (TST).

77. DENTAL UNIT WATERLINE
DISINFECTION &
MANAGEMENT(DUWL)
Source of water to dental unit is either through municipal supply or
through wells ;
After entering the unit it passes through multiple channel control box
which distributes water to hoses feeding various attachments;
The lines have a very small bore and hence bacteria tend to form
biofilms on internal surfaces unless they are regularly cleaned &
disinfected;
Guidelines of ADA are that the water delivered to patients from
DUWL during dental procedure should not contain more than 200
colony forming units of bacteria per ml of water.

78. OPERATORY ASEPSIS
In the dental operatory, operatory surfaces that are repeatedly
touched or soiled are best protected with disposable
covers(barriers)that can be discarded after each treatment.
 For dental unit trays, paper, plastic film or surgical pack
wraps (paper or towels) should cover the entire tray.

79. • Gigasept which contains Succinaldehyde and
Dimethoxytetrahydrofuran are used for disinfection of
plastic and rubber materials eg: dental chair

80. ASEPSIS OF SURGERY
THEATERS
Fumigation is done by two methods:
1. Electric boiler method- 500 ml of
formaldehyde (40%) added to distilled
water in electric boiler. When the water
heats fumes are generated.
2. Potassium permanganate – heat is
induced by oxidative action of potassium
permanganate. 500ml of formaldehyde is
added to potassium permanganate which
reacts and generates fumes.

81. DENTAL RADIOLOGY ASEPSIS
Always wear gloves when exposing radiographs and handling
contaminated film packets;
Use heat tolerant or disposable intra oral devices whenever
possible;
Digital radiography sensors :use disposable polythene sheets
over sensor to prevent cross contaminations.

82. LABORATORY ASEPSIS
Dentists usually send impression material, dentures, biopsy
specimen etc to laboratories;
Blood & saliva should be washed under running water and
proper disinfectant , & if appropriate, place in plastic bags and
send to laboratory.
Biopsy specimens should be kept in sturdy container with secure
lids to prevent leakage during transport.
Care should be taken when collecting biopsy specimen to avoid
contamination of external surface of container.

83. HANDPIECE ASEPSIS
Asepsis of high-speed handpiece involve:
Asepsis of hand-piece external surfaces and crevices,
Turbine chamber disinfection.

85. METHODS TO BE FOLLOWED
BY OPERATOR FOR PROPER
DISINFECTION

86. HAND WASHING

87. For routine dental examination procedures, hand washing is
achieved by using either a plain or antimicrobial soap and water.
At the beginning of a routine treatment period, watches and
jewellery must be removed and hands must be washed with a
suitable cleanser.
Hands must be lathered for at least 10 seconds, rubbing all
surfaces and rinsed thoroughly with water.

91. Hegde et.al., in their study stated that the bar soap under
the "in use" condition is a reservoir of microorganisms
and washing hands with such a soap may lead to
spread of infection.
 (Microbial contamination of "in use" bar soaps in dental
clinics. Indian J dent res2006;17:70-3)

92. PERSONAL BARRIER
PROTECTION
It is essential to protect the skin and the mucous membranes of
personnel from exposure to infectious materials.
The various barriers are gloves, masks, protective eye wear,
surgical head cap & overgarments.

93. GLOVES
Types:
Latex gloves;
Vinyl gloves.

95. PRECAUTIONS TAKEN FOR
LATEX ALLERGIC PATIENTS
Be aware that latex allergens in the ambient air can cause anaphylactic
symptoms among persons with latex hypersensitivity.
Patients with latex allergy can be scheduled for the first appointment of
the day to minimize their exposure to airborne latex particles.
Have emergency treatment kits with latex free products available at all
times.
Mild type I reactions without respiratory distress can be treated with
topical steroids and antihistamines
Severe hypersensitivity with respiratory distress, call for medical
assistance by monitoring airway, breathing and circulation.

96. MASKS
Types:
1.Surgical masks (required to have
fluid-resistant properties).
2.Procedure or isolation masks.
• Made up from a non-woven fabric.
Layers of a mask:
1. An outer layer
2. A microfiber middle layer - filter generated particles
3. A soft, absorbent inner layer - absorbs moisture.

97. EYE WEAR
Causes of eye damage:
1. Aerosols and spatter may transmit infection.
2. Sharp debris projected from mouth while using air turbine
handpiece, ultrasonic scaler may cause eye injury.
3. Injuries to eyes of patients caused by sharp instruments
especially in supine position.

98. FOOTWEAR
Most hospitals have their own policies regarding footwear.
Footwear with open heels or holes across the top can increase
the risk of harm to the person wearing them due to more direct
exposure to body fluids or of sharps being dropped.

99. PRECAUTIONS TO AVOID
INJURY
Establish practices to protect personnel
while handling or processing sharp devices.
Sharp end of instruments must be pointed
away from the hand;
Use SCOOP METHOD of needle capping.
Place the cap on the benchtop and hold the
syringe in one hand. Slide the needle into the
cap, then lift it up and snap it on securely
using only one hand.

100. DISPOSAL OF WASTE
Any waste that has been in contact with human sources will
possibly support microbial growth.
 Types of waste:
Wastes in a health care facility cover a diverse range of materials
that can be divided into two broad categories:
1.Non-medical waste (or non-hazardous waste) general or non-
medical waste posses no additional risk of injury or infection to
staff, to patients, to visitors, or to the community at large. It is
similar in composition to household trash.
Eg: household wastes, vegetables etc..

101. 2.Medical waste (hazardous waste) medical waste consists of
several different subcategories such as:
A. Infectious waste:
Examples include:
• Blood and blood products, used catheters and gloves, swabs,
bandages, and gauze etc

102. B.Anatomic wastes:
• Anatomic wastes consists of body parts and tissues (Eg.,placenta),
waste from clinical labs.
C.Sharps waste:
• Sharps waste consists of used syringes, needles, scalpels and blades,
etc.
D.Chemical waste :
• Waste containing chemical substances Eg., Laboratory chemicals,
empty bottles of lab or pharmacy chemicals, cleaning agents and
others.
E.Pharmaceutical waste:
• Waste containing pharmaceutical substances. Examples include:
expired, unused & contaminated pharmaceuticals, expired drugs,
vaccines and seras.

103. SORTING
Medical waste that must be specially handled to reduce the risk
of infections.
Therefore, sorting the waste at the point at which it is generated
can greatly reduce the amount that needs special handling.
Colored plastic bags should be used to help distinguish between
general-and medical-waste.

104. COLOUR CODES:

106. OCCUPATIONAL SAFETY &
HEALTH ADMINISTRATION (OSHA)
It is regulatory body that enforces the requirements that employers must
protect employees from exposure to potentially infectious materials during
work.
Osha- sets mandatory training for dental employees.
Following must be available for all dental employees according to osha.
Copy of blood borne pathogens and their way of spread;
Information about symptoms of infectious disease;
Information regarding hepatitis B vaccine;
Information about exposure reduction including personal protective
equipment(PPE);
Information about selection, placement, use, removal, disinfection ,
sterilization & disposal of PPE;
Material safety data sheets(MSDS) & information about labelling waste.

107. ULTRASONIC SCALARS:
Soak inserts in a container containing 70% isopropyl alcohol for
removal of organic debris.
Rinse cleaned inserts thoroughly in warm water to remove all
chemicals. As a final rinse, replace the insert into the scaler
handpiece and operate the scaler for 10 seconds at the maximum
water flow setting to flush out any retained chemicals.
Dry inserts completely with air syringe.
Package in proper wrap, bags, pouches, trays, or cassettes. Add
spore tests and chemical indicators.
Ethylene oxide or autoclaving is the preferred method of choice.
Dry heat and chemical vapor methods of sterilization are
considered ineffective methods with risk of damage to materials.

108. SUTURES:
Sutures are pre sterilized by gamma radiation .sutures are re-
sterilized by two methods are
1. Soak for a full 10 minutes completely immersed in povidone
iodine 10% solution, then rinse in sterile saline/water.
2. Ethylene oxide – gas sterilisation.

109. PRE STERILIZATION OF
COMMONLY USED
INSTRUMENTS

110. SYRINGES USUALLY STERILIZED BY
ETHYLENE OXIDE.
Process consist of three phases:
Pre-conditioning, sterilization and aeration.
Biological indicators are placed into the sterilization load, and the load
is placed into a preconditioning room;
The product is then moved into the sterilization chamber where it is
treated with ethylene oxide gas;
Following exposure, the product is transferred into an aeration cell for
dissipation of the ethylene oxide;
Biological indicators are removed from the product and tested;
Product is released into market once the biological indicators have
completed tested and the ethylene oxide residual levels are acceptable.

111. SURGICAL GLOVES,MOUTH
MASKS, BONE GRAFTS AND
GTR MEMBRANES

113. CONCLUSION
There are numerous microorganisms in our environment
which are potential cause of infection.
It is therefore essential for us to protect ourselves & the
patients from cross infection.
Thus, a deeper knowledge of sterilization & disinfection is of
paramount importance for us.

114. REFERENCES
TEXTBOOK OF MICROBIOLOGY, STERILIZATION AND
DISINFECTION, 7TH EDITION, ANANTHANARAYAN
TEXTBOOK OF CLINICAL PERIODONTOLOGY, NEWMAN, TAKEI,
CARRANZA, 11TH EDITION.
OPERATIVE DENTISTRY, INFECTION CONTROL, 4TH EDITION,
STURDEVENT.
GROSSMANS ENDODONTIC PRACTICE, 11TH EDITION,
INSTRUMENT STERILIZATION.
INTRODUCTION TO STERILIZATION DISINFECTION & INFECTION
CONTROL, 2ND EDITION, JOAN F GARDNER
STERILIZATION AND DISINFECTION OF DENTAL INSTRUMENTS
BY ADA

115. DISINFECTION & STERILIZATION OF DENTAL INSTRUMENTS TB
MED 266, 1995
CDC, GUIDELINES FOR DISINFECTION & STERILIZATION IN
HEALTH CARE FACILITIES 2008.
EFFECTS OF STERILIZATION ON PERIODONTAL INSTRUMENTS,
J PERIODONTAL;1982;53;7
NEW CDC GUIDELINES FOR SELECTED INFECTION CONTROL
PROCEDURES, CHRIS MILLER.
CDC GUIDELINES FOR INFECTION CONTROL IN DENTAL
HEALTH CARE SETTINGS, DEC19, 2003/VOL.52.
STERILIZATION OF ULTRASONIC INSERTS.