sterilisation in Dentistry /certified fixed orthodontic courses by Indian dental academy

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STERELISATION IN
DENTISTRY

INDIAN DENTAL ACADEMY
Leader in continuing dental education

INTRODUCTION

Micro organisms are ubiquitous. Since they cause
contamination, infection and decay , it becomes
necessary to remove or destroy them from
materials or from areas.

Micro organisms that are most commonly
seen are
bacteria and microscopic fungi.
They may be pathogenic or non
pathogenic, present on both animate and
inanimate surfaces.
They are divided into

a) Vegetative bacteria
b) Sporulating bacteria


DEFINITIONS

Sterilizing:- Refers to killing of all microbial life.
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: is defined as the destruction or removal of all
pathogenic organisms or the organisms capable of giving rise to
infection
Sepsis:- Refers to presence of infection, infectious
material or agent.


ASEPSIS:- It is the prevention of contact with
pathogens.
Antisepsis:- Is used to indicate the prevention of
infection, usually by inhibiting the growth of bacteria in
wounds or tissues.
Bactericidal:- These are agents which are able to kill
bacteria.

Bacteriostatic:- These agents prevent the
multiplication of bacteria.


METHODS OF STERILIZATION
PHYSICAL










Sunlight
Drying
Dry heat
Flaming
Incineration
Hot air oven
Filtration
Radiation








Moist heat
Pasteurization
boiling
steam under normal and
high pressure
Ultrasonic and Sonic
vibrations

CHEMICALS

Alcohols
 Aldehydes
 Halogens
 Phenols
 Surface-active agents
 Metallic salts
 Gases


The purpose for which the sterilization is carried out
depends on
→ Materials which has to be sterilized
→ Nature of microorganism that are to be removed
or destroyed


SUN LIGHT



Sunlight has high bactericidal activity due to presence of U.V.
and heat rays.
It’s sterilizing power varies according to the circumstances.



Bacteria suspended in water are readily destroyed by exposure



of sunlight
Spontaneous sterilization under natural conditions.

Limited clinical utility.


DRYING






Moisture is essential for bacteria
Drying therefore has a deleterious effect on most bacteria.
Viruses are more resistant
Highly unreliable
Spores are unaffected


HEAT










Most reliable method for sterilization
The factors affecting sterilization by heat are
→ Nature of the heat
moist heat is more effective than dry heat
Time and temperature – the time required for
sterilization is inversely proportional to
The temperature of exposure. this can be expressed as
thermal death time
Kills by protein denaturation, oxidative damage and the
toxic effect of elevated levels of electrolytes


Dry
heat
steriliz
ation

flaming

incineration

Hot air oven


Flamming:







Most primitive of all methods
Used for sterilization of Innoculating
loops or wires, points of forceps and
searing spatulas.
The instruments are held in a bunsen
flame till they become red hot
Burs dipped in alcohol & flammed 2 or
3 times


INCINERATION
•

•

This is an excellent method
for safely destroying materials
such as contaminated cloth,
animal carcasses and
pathological materials
Plastic like PVC and
polythene can also be
incinerated

HOT AIR OVEN










Widely used method of
sterilization by dry heat.
Temperature:160 c- 170 c (320 –
340 F)
Time period: 1hr
Used to sterilize
glassware, forceps, scissors, scalpel
, glass syringes, swabs, liquid
paraffin, dusting powder etc.
Hot air is a bad conductor of heat
and its penetrating power is low.
Bacterial spores require a
temperature of 140 c for 3 hours
to get killed


INSTRUCTIONS FOR HOT AIR OVEN


The oven is usually heated by electricity.



It must be fitted with fan to ensure even distribution of air
& elimination of air pockets.



It should not be overloaded



Glassware should be dry before placing into the oven.

 The

oven must be allowed to cool slowly for about 2 hours

before the door is open since the glassware may crack by
sudden uneven cooling.
 Rubber

materials except silicone rubber will not withstand

high temperature


ADVANTAGES

DISADVANTAGES

1. Preserves the sharpness of
metallic instruments
2.Does not cause rust, leaves the
instruments dry & can be
used with packing
3.Reliable & economical
4.Does not dull cutting edges.

1.Longer processing time ( 1-2 hrs)
2.Does not conduct heat efficiently

3.High temperatures pose a hazard
to operators and may damage
more heat sensitive items such as
rubber or plastic.
4.Has poor penetration.
5.May discolor and char fabric.
6.Destroys heat labile items.
7.Cannot sterilize liquids.

8.Unsuitable for hand pieces.
9.Cooling of the oven takes a long
time.


COX STERILIZER


Rapid heat transfer sterilizer



Operates at 370-375 F (190 C).



Sterilization time 6 minutes for unwrapped ,and 12 minutes for
wrapped instruments.

Advantages




No corrosion of carbon steel
instruments and burs.
Cutting edges are not dulled.


GLASS BEAD / SALT STERILIZER


Temperature between 425 F(218 C) and 475 F(246 C)



Broaches, files, silver cones and reamers sterilized in 5s
Absorbent points & cotton pellets in 10s

o

Not suited for hollow instruments


Temperature below
100 c

Temperature at 100 c
Steam under pressure
Steam at atmospheric
pressure


TEMPERATURE BELOW 100C
Pasteurization





Holder method : 63 c – 30 mins
Flash method : 72 c – 15 – 20 seconds followed
by cooling quickly to 13 c or lower
All non sporing bacteria's – mycobacterium,
brucella, salmonella are destroyed.
Vaccines of non sporing bacteria in special bath
for 60 c – 1 hr


TEMPERATURE AT 100°C
BOILING









veg. bacteria – 90 – 100 c
spores – prolonged periods of boiling
INSTRUCTIONS:
Add 2% sodium bicarbonate to water ( increases the
efficiency)
Hard water should not be used
Not recommended for surgical instruments
Materials should be immersed in water & lid should not be
opened for 10 – 30 min.


STEAM AT ATMOSPHERIC PRESSURE


It is used to sterilize culture media



Sterilization is done for 90 min , but for media containing sugars or

gelatin an exposure of 100 c for 20 min on 3 successive days is used. This
is known as TYNDALLISATION or INTERMITTENT
STERILISATION.
TYNDALLISATION:


Ist exposure – kills bacteria in vegetative form & in next 24 hrs spores
germinate into veg. form.



IInd exposure – remaining veg. forms are destroyed.



IIIrd exposure - as a precaution (to kill if any veg. forms or spores
remaining)


STEAM UNDER PRESSURE
AUTOCLAVE

This is the most effective method of sterilization



Autoclave is a chamber which can withstand
pressure of greater than 2 atmosphere.
Moist heat (steam)of 121 c under a pressure of
15psi for 15 min is used.


PRINCIPLE:
 Saturated steam has penetrating power & when it comes in
contact with cooler surface it condenses & gives latent heat to
that surface.
 This ensures moist conditions for killing the microbes.
 Temperature : 108 c – 147 c
Operates at 121 C at 15 lbs for 15 to 20 min.
Flash sterilizaion : 134 C at 20 to 30 lbs for 3 to7min












There are three major factors required for effective
autoclaving: pressure, temperature and time.
Pressure:
It is expressed in terms of psi (pound per square
inch) or kpa (kilo Pascal's: kpa = 0.145psi).
Temperature:
To achieve required pressure, the temp must be
reached and maintained at 121 degree C (250 F) with
the increase in temperature and pressure, super heated
steam is formed. The exposure to this super heated
steam brings about the sterilization.
Time:
Higher temperature and greater pressure, shorter
the time required for sterilization. At 15 psi pressure, the
temperature of steam can reach 121 degree c . The time
required to kill all living organisms at this temp is 15
mins, at 126 degree for 10 mins, and at 134 degree c for
3 mins sterilization can be complete.

Presently, two types of autoclaves are
available.
1. Porous load autoclaves:
To achieve complete sterilization, 121
degree at 20 psi are maintained for 20
mins, the articles which can be sterilized by
this method include:
towels for draping.
suture materials.
cotton rolls, rubber gloves etc.
2. Small portable bench model type
autoclaves:



To avoid or minimize corrosive action of
steam on metals, the use of following
agents have been reported.
 Crawford and Oldenburg (1967)
recommended addition of ammonia to the
autoclaves.
 Accepted dental therapeutics (1977)
recommends use of dicylohexylammonium
nitrate or cyclohexylamine and decylamine.
 Bertocoltti and hurst (1978) recommend 2%
sodium nitrate.


WRAPPING INSTRUMENTS FOR
AUTOCLAVING:







Instruments must be cleaned, but not necessarily dry. Closed (
non perforated ) container ( closed metal trays, copper glass
vials ) and aluminium foils cannot be used, because they
prevent the steam from reaching the inner sections of the
packs.
Cassettes, drums, trays with opening on all sides may be used.
Packaging used for autoclaving must be porous, to permit
steam to penetrate through; and reach the instruments.
The materials used for packaging could be fabric or sealed
biofilm/paper pouches, nylon tubing, sterilization wraps and
paper wrapped cassettes.


PREPARATION FOR STERILIZATION

INSTRUMENT CASSETTE


CASSETTE WRAPPED IN
POROUS AUTOCLAVE PAPER


INSTRUMENTS IN SURGICAL PACK


PROCEDURE


Articles are placed in cabinet & doors are bolted.



Vacuum of about 20 inches is applied.



Steam is introduced at pressure of 15 lbs/sq.inch & when
temperature is reached to 121 c time is noted &
sterilization is continued for 20 mins.



Materials like surgical gauze, dressings etc, should be dry
before removing.



Steam is removed & dry heat is introduced from outside
into the cabinet for 15 mins.


Advantages:
1. Short efficient cycle time.
2. Good penetration.
3. Ability to process a wide
range of materials.
4. Reliable

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.
6.Heat & moisture may act overtime
to dull & rust instruments,
weaken certain plastics &
rubber items


FAILURES OF AUTOCLAVE


If dressing or theatre garments are tightly packed

then steam cannot circulate freely.


Failure due to subsequent re-contamination.



Defect in steam- air mixed.



Defect in design of apparatus.


TESTS FOR EFFICIENCY OF HEAT STERILIZATION:
1. Thermocouple: This is a thermometric testing and a reliable gauge of
efficiency. One recording is taken from a thermocouple placed inside a
test pack of towels and a second one from the chamber drain.
comparison between the two recordings gives a good guide
regarding the speed at which the steam penetrates the load.
2. Brown’s test : These are ampoules that contain a chemical indicator;
which changes its color; from red through amber to green at a specific
temperature..
3. Autoclave tapes: This is a tape printed with sensitive ink that undergoes
a color change at a specific temperature. This test forms the basis of
the Bowie- Dick test for high vacuum autoclaves.
With the application of temperature of 134 degree c for 3.5 mins, there is a
uniform development of bars throughout the length of the strips. This
shows that the steam has passed freely and rapidly to the center of the
load.

CHEMICLAVE



A combination of formaldehyde, alcohol, ketone, acetone and
steam at 20psi serves as an effective sterilizing agent.



Temperature used is 134 c for 20 mins.

Advantages


Minimal corrosion.



Dry instruments are available after cycle.
DISADVANTAGES



Long aeration period required.



Adequate ventilation required.



Chemical hazards possible.


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.
Following types of filters are usedCandle filters





Used for purification of water for industrial and
drinking purposes.
They are 2 types:
Unglazed ceramic filters - Chamberland & Doulton
Diatomaceous earth filters - Berkfeld & Mandler


Asbestos filters












Are disposable.
Single use discs.
They have high adsorbing capacity and tend to
alkalinize filtered liquids.
Sintered glass filters
Prepared by heat fusing finely powdered glass
particles of graded sizes.
They have low absorptive property
Can be cleaned easily
Brittle and expensive.
Membrane filters
Routinely used in water purification and
analysis, sterilization and sterility testing
The preparation of solutions for parenteral use.


RADIATON

Two types of radiation are used for sterilization purpose


Nonionizing radiation – U.V.Rays, Infrared rays



Ionizing radiation

- X-Rays , Gamma Rays, Cosmic Rays

NON-IONIZING RADIATION

•

Electromagnetic rays with longer wavelengths are used.

•

Infra red radiation is considered as a form of hot air sterilization.

•

Infra red radiation is used for rapid mass sterilization of pre packed
items such as syringes and catheters.

•

UV radiation is used for disinfecting enclosed areas such as entryways,
operation theatres and laboratories


IONIZING RAYS


ex : X-rays, gamma rays, cosmic rays



Lethal to DNA & other vital cells constituents.



High penetrating power



No increase in temperature ( cold sterilization)



Gamma rays are used for sterilizing plastic syringes, swabs,
culture plates, catheter, animal feeds, various types of rubber,
cardboard, oils, greases, fabrics, dental implants & metal foils.


ULTRASONIC AND SONIC VIBRATIONS


Ultrasonic and sonic waves have bactericidal property.



survivors are found even after treatment.



Hence it has no practical value in sterilization and
disinfection.



Safest way to clean sharp instruments.



Effective up to 9 times more than hand cleaning


CHEMICAL STERILIZATION

Ideal requirements for antiseptic/disinfectant:


Wide spectrum of activity & effective against all micro-organisms. Eg:
bacteria, spores, viruses, protozoa & fungi



Effective in acid/alkaline media & speedy action



High penetrating power & stable



Compatible with other antiseptic & disinfectants



Should not corrode metals



Not cause local irritation/sensitization



Not interfere in healing



Economical , easily available, safe & easy to use


ALCOHOL



E.g.: methyl alcohol, ethyl alcohol, isopropyl alcohol
Methyl alcohol is effective against fungal spores

Uses:



To treat cabinets & incubators affected by fungus
Cabinets & chambers are wiped with methanol

Method:



A pad moistened with methanol & dish of water ( to ensure high
humidity) are kept inside & the incubator is left in working temperature
for several hours.

Disadvantages


Methanol vapors are toxic & inflammable


ETHYL AND ISOPROPYL ALCOHOL


Ethyl & isopropyl are widely used



Alcohol acts by denaturing the proteins



No action on spores



Concentration: 60 – 70 % in water



Isopropyl is preferred over ethyl because



It is better fat solvent,



More bactericidal & less volatile.



Uses : sterilization of clinical thermometers.


ALDEHYDES
FORMALDEHYDE


Active against amino group in protein molecule



Bactericidal & sporocidal, lethal against viruses
Uses:



To preserve anatomical specimens



Destroys anthrax spores in hair & wool



10 % formalin + 1/2 % sodium tetra borate used to sterilize clean metal
instruments



Formalin gas is used to sterilize instruments & heat sensitive catheters, to

fumigate wards, sick room & labs,Clothing, bedding, furniture & books
Disadvantages:


Gas is irritant & toxic when inhaled


GLUTERALDEHYDE


Similar to formaldehyde



Tubercle bacilli, fungi & viruses



Less toxic & irritant to eyes & skin



No deleterious effect on lenses –
cytoscopes & bronchoscopes



Used safely to treat corrugated rubber
anesthetic tubes & face masks. Plastic
endotracheal tubes , metal instruments
& polythene tubing

DYES




I. ANILINE
II. ACRILINE
Used as skin & wound antiseptics
Bacteriostatic on high dilution but low bactericidal

ANILINE DYES:




Eg: brilliant green, malachite green & crystal violet
More active against Gram +ve than Gram –ve
No action against tubercle bacilli

MODE OF ACTION:
React with the acid in the cell
Used in microbiology labs as selective agents in culture media


ACRILINE DYES:
 Active against Gram +ve than Gram –ve
 ex: proflavine, acriflavine, euflavine & aminarine
MODE OF ACTION:
 Impair the DNA complex of organism & destroys the reproductive
capacity of cell.

HALOGENS



ex: Iodine and chlorine



Iodine is bactericidal with moderate action against spores



Active against tubercle bacilli and viruses



Chlorine & its compounds have been used as disinfectants in



Water supplies, swimming baths, food & dairy industries.

QUATERNARY AMMONIUM COMPOUNDS


Benzalkonium chloride is widely used as both antiseptic &
disinfectant.



Antibacterial spectrum is similar to alcohols.



Limited to Gm+ve & some Gm-ve organisms.



Not effective against spores, viruses, mycobacterium
tuberculosis


PHENOLS




Obtained by distillation of coal tar between temperatures of 170 - 270 c
Lethal effect of phenol is due to their capacity to cause cell membrane damage
& lysis of cell



Low concentration – precipitates proteins.



Phenol ( carbonic acid) powerful microbicidal substance



Lysol & cresol – active against wide range of organisms &
toxic to humans



Active against Gram + ve & fairly against Gram–ve



Aqueous solution used in treatment of wounds.

GASES


ETHYLENE OXIDE


Time required for sterilization – 10 - 16 hrs.



Highly permeable & colorless liquid with a boiling point of 10.7 c



But at normal temperature & pressure is a highly penetrating gas.



Highly inflammable & in concentration in air greater that 3 % is highly
explosive.

If mixed with carbon dioxide and nitrogen explosive tendency is
eliminated
MODE OF ACTION:


Acts by alkylating the amino, carboxyl, hydroxyl and sulfhydryl groups
in protein molecules and also reacts with DNA & RNA

Uses:


Tubing, handpeices, & prosthetic appliances



Unsuitable for fumigating rooms due to explosive property
Successful in sterilizing – glass, metal, paper
surfaces, clothing, plastics, soil, food stuff, & tobacco.
FORMALDEHYDE



Widely used for fumigating operation theatres & other sick rooms.



Low temperature steam & formaldehyde (LTSF)



Designed primarily to sterilize cytoscopes & other heat sensitive materials.



Applicable to wide variety of equipment that withstands temperatures of 70 75 c


BETAPROPIOLACTONE (BPL)


Condensed product of ketone & formaldehyde with boiling point
of 163 c



Low penetrating power but more efficient for fumigating purpose
than formaldehyde



Rapid bactericidal action but carcinogenic



0.2% BPL is used for sterilizing biological products



Kills all micro-organisms and viruses


SURFACE ACTIVE AGENTS


These are the substances which alter energy relationships at
interfaces producing a reduction of surface(or)interfacial tension.



They are widely used as wetting agents ,detergents and emulsifiers



These are broadly classified as
→

Anionic

→

Cationic

→

Nonionic

→ Amphoteric


METALLIC SALTS


Germicidal action depending upon concentration



Salts of silver, cu, Hg, are used as disinfectants



They are protein coagulants & have the capacity to combine
with free sulphydryl group of cell enzymes



Mercuric chloride used in medicine but highly toxic



Organic compounds like thiomersal, phenyl mercury nitrate, &
mercurochrome are used as mild antiseptics.



Cu. Salts are used as fungicides.


LIQUID CHEMICAL STERILISATION


This is the method used only with heat
sensitive materials



Items should be immersed in the
solution for – 10 hrs



Effectiveness cannot be verified by
biological monitored, so has little value.



Used only as secondary method for
items that cannot be sterilized by any
other method


ARTICLES AND METHOD OF STERILIZATION

ARTICLE


Disposable syringes



Non disposable
syringes

METHOD OF
STERILIZATION
 Gamma radiation
 Ethylene oxide
 Autoclaving
 Hot air oven
 Infrared radiation
 Boiling at 100 c


Suture materials except catgut

Autoclaving

Catgut

Ionizing radiation

Bone and tissue grafts,
adhesive dressings, Implants

Ionizing radiation

Dressings, Aprons, Gloves,
Catheters.

Autoclaving

Sharp instruments

5%Cresol

Water

Chlorine as hypo chlorites

Skin

Tincture iodine, savlon, spirit
(70%ethanol)







PROCEDURES BEFORE www.indiandentalacademy.com
STERILIZATION
Pre sterilization cleaning

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







Drying and cooling
Distribution.
Storage: After sterilization the instruments are stored in a central
sterilizing area
Sterilization area should be well separated to avoid probable
contamination


CAUSES OF STERILIZATION FAILURE














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

MONITORING OF STERILIZATION



Sterilization must be tested weekly with biological spore tests
using heat resistant spores and tested daily with process
indicators.



Sterilizing monitoring has four components:
1) Sterilization indicator on the bag and date of sterility
2) Daily process indicator strips
3) Weekly biological spore tests
4) Documentation note book


SPORE TESTING
Once per week
 After training of new sterilization personnel
 Whenever a new type of Packaging
material is used
 During initial uses of a new sterilizer
 First run after repair of sterilizer
 With every implantable device and bold
device until results of test are known
 After any other change in sterilization
procedure


ASEPSIS


Surface asepsis of dental instruments
can be
achieved by two methods:
 By cleaning and disinfecting
contaminated surfaces.
 Preventing the surface from becoming
contaminated by use of surface cover.


CLASSIFICATION OF DISINFECTANTS

1. Phenol derivatives:
Phenol
Cresol

Resorcinol
Hexyl resorcinol
Hexachlorophene

3. Halogens

Iodine

Iodophores
Chlorine
Chloroform

Chloroxylenol
2. Oxidizing agents

4. Bisguanides

Potassium permanganate
Hydrogen peroxide

Benzoyl peroxide

Chlorhexidiene

DISINFECTANTS


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


INFECTION CONTROL





INFECTION CONTROL:- It is defined as the selection and use of
procedures and products to prevent spread off infectious diseases.

Infection control involves 2 basic factors
Prevention of spread of microorganisms from their hosts
Killing and removal of microorganisms from objects and surfaces.
Infection through any of the routes requires the following
1)Susceptible host
2)Pathogen with sufficient infectivity and numbers to cause
infection
3)Portal through which the pathogen enters the host


AN INFECTION TO OCCUR REQUIRES ALL
THE FOLLOWING CONDITIONS TO BE
PRESENT

A
susceptible
host

A pathogen
with
sufficient
infectivity
and numbers
to cause
infection.

A portal
through
which the
pathogen
may enter
the host.

A reservoir
or source
that allows
the pathogen
to survive
and multiply
e.g. blood


WHY IS INFECTION CONTROL IMPORTANT
IN DENTISTRY?


Both patients and dental health care personnel
(DHCP) can be exposed to pathogens



Contact with blood, oral and respiratory secretions,
and contaminated equipment occurs



Proper procedures can prevent transmission of
infections among patients and DHCP


OBJECTIVES OF INFECTION CONTROL


Reducing the no. of pathogens



Breaking the cycle of infection



Eliminating cross contamination


INFECTIONS IN DENTAL OPERATORY
Autogenous infections






Are those caused by microbes that the patient carries on or in his
or her own body.
The microbes usually are harmless within the oral cavity, but may
cause disease if they enter the tissues.
Eg: infective endocarditis, oral abscesses.

Cross infections






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.


PATHWAYS OF CROSS INFECTION


Patient to practitioner



Practitioner to patient



Patient to patient



Clinic to community



Clinic to practitioners family



Community to patient.


1. Source
of infection

4.
Susceptible
host

Factors
affecting
transmission
of infection

3.Route of
transmission

2. Means of
transmission


1.Source of infection:

-a patient ,member of
dental team.
2.Means of
transmission:

-microorganisms
in the blood,

present

-contact with blood or
saliva mixed with blood
may
transmit
pathogenic
microorganisms from
one person to another.

3.Route of transmission:
A. Inoculation:
-direct contact,
-accidental injury with a
contaminated needle
Ex: hepatitis, herpes simplex,
clostridium tetani,
staphylococcus.


B. Inhalation:
-aerosols and splatter.
Ex: CMV, varicella zoster,
mycobacterium tb, streptococcus
pyogenes, candida, rubella.


Modes of disease transmission:
1.Personal contact
2.Carrier contact
3.Droplet transmission
4.Indirect transmission


PERSONAL
CONTACT


Diseases spread from one person to other by direct contact



Eg: veneral diseases such as AIDS, herpes, syphilis. Contact with
contaminated blood, saliva and mucous may spread them.

Carrier contact


Person who harbours a pathogenic microorganism without getting
the disease himself is considered as carrier.



The carrier often exhibits no symptoms. Eg: serum hepatitis, AIDS

Droplet transmission


It occurs when the person breathes, talks, sneezes or coughs.



Eg: common cold, flu.


INDIRECT TRANSMISSION
Face
 Clothing
 Cabinets
 Restorative
material packs
 Light handles
 X-rays
 Patient charts
 Pumice pan
 Patient towels
 Cotton roll
















Hair
Handles of drawers
Medicament bottles
Cement jars
Anesthetic supplies
Light switch
X-ray tube head
Prosthesis
Exposed instruments
Patient bibs
Disposable items


1. Medical history

2. Universal precautions/ standard precautions

3. Personnel health elements


4. Sterilization and disinfection of patient care items

5. Dental unit waterline (DUWL) contamination

6. Environmental infection control

UNIVERSAL PRECAUTIONS



Identification of the infected patients by medical history,
physical examination or lab tests for each and every
individual



Are a set of precautions designed to prevent transmission
of HIV, HEP B and other blood borne pathogens when
providing 1st aid or healing care.



All the patients are considered potentially infectious



Involve the use of protective barriers such as gloves,
gowns, aprons, masks, protective eye wear



It is also recommended to prevent injuries caused by
needles, scalpels and other sharps.


PERSONNEL HEALTH ELEMENTS OF AN
INFECTION CONTROL PROGRAM


Education and training



Immunizations



Exposure prevention and post exposure management



Medical condition management and work-related
illnesses and restrictions



Health record maintenance




The Advisory Committee of Immunization Practices
(ACIP):

1.

Tetanus and diphtheria – 3 doses: 1 every 10 yrs.

2.

Influenza – 1 dose annually

3.

Pneumococcal – 1 dose

4.

Hepatitis B – 3 doses(0, 1-2, 4-6 months)

5.

MMR – 1 dose

6.

Varicella – 2 doses

7.

Meningococcal – 1 dose

8.

Annual tuberculin tests

9.

Frequent throat cultures


HAND HYGIENE


Hands are the most common mode of pathogen transmission



Reduce spread of antimicrobial resistance



Prevent health care-associated infections

SEMMELWEIS introduced the concept of hand washing with lime.

HAND HYGIENE DEFINITIONS



Handwashing

 Washing hands with plain soap and water


Antiseptic handwash

 Washing hands with water and soap or other detergents containing an
antiseptic agent


Alcohol-based handrub

 Rubbing hands with an alcohol-containing preparation


Surgical antisepsis



Handwashing with an antiseptic soap or an alcoholbased handrub before operations by surgical personnel


SPECIAL HAND HYGIENE CONSIDERATIONS


Use hand lotions to prevent skin dryness



Consider compatibility of hand care product



4% chlorhexidiene gluconate and 3% PCMX
are efficient scrubbers s with gloves (e.g., mineral oils
and petroleum bases may cause early glove failure)



Keep fingernails short



Avoid artificial nails



Avoid hand jewelry that may tear gloves

HAND WASHING PROCEDURES


Frequently missed areas of the hands during
washing

Most Frequently missed
Less Frequently missed
Not missed


GLOVES:


Gloves should be worn when contact with blood.



When contacting any contaminated surfaces, & objects.



Gloves are single-use items and should be replaced as soon as contaminated or
immediately if torn, punctured, or when their integrity is compromised



Single-use gloves should not be washed for reuse.



Washing gloves causes "wicking," (invasion of liquids through

undetected holes in the latex gloves).


Rinsing to remove excess powder or cornstarch is permissible.



Deterioration of gloves may be caused by disinfectants, oils, oilbased emollients, and improper storage, such as exposure to heat.


Sterile
surgical
gloves.

Non sterile
latex
gloves.

Vinyl
examination
gloves.

Utility
gloves.


GLOVE PLACEMENT


Always glove and deglove infront of pt



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 wear new gloves


Wash hands promptly after glove removal


LATEX HYPERSENSITIVITY


Patients or clinicians may develop a sensitivity
to rubber latex



Symptoms range from dermatitis to a life

threatening anaphylactic shock


Only available treatment is avoiding all contact



Latex sensitivity is due to protein allergens


REACTION TO GLOVE ALLERGY


GENERAL RECOMMENDATIONS
CONTACT DERMATITIS AND LATEX ALLERGY


Educate DHCP about reactions associated with

frequent hand hygiene and glove use


Get a medical diagnosis



Screen patients for latex allergy



Ensure a latex-safe environment



Have latex-free kits available (dental and emergency)


MASKS OR FACE SHIELDS








Masks along with eyewear &
face shields protect against
aerosols.
Change the masks every hour or
change for every patient.
Masks covering mouth and nose
minimize inhalation of aerosol &
protects the mucosal
contamination.
Types: cone, ear loop & surgical
95% of filtration efficiency in
presence of 3-5 micrometer
particles.
EAR LOOP MASKS


CHARACTERISTICS OF IDEAL MASK











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

materials:
Plastic foam, fiber glass, synthetic fiber
mat, paper.
Mask removal:
-grip side elastic or tie strings to
remove.

-never

handle

the

outside

of

a

contaminated mask with gloved or
bare hands.
Never place the mask under the chin.




Use
of
eyewear

protective

-to avoid eye infections.
-contamination can be introduced
from saliva, biofilm, carious
material,

pieces

restorative

materials

of

old
during

cavity preparations, bacteria
laden calculus during scaling
and any other microorganisms
contained

splatter.

in

aerosols

or

Features:
-wide coverage, with wide
shields, to protect around
the eye.
-shatterproof:

made

of

strong, sturdy plastic
-lightweight
-flexible

and

with

round

smooth edges to prevent

discomfort

if

pressed

against the nose or ears.
-Easily disinfected.


Types:
-goggles
-eyewear with side shields
-eyewear with curved
frames
-post mydriatic spectacles
used by
ophthalmologists.
-Child sized.


Care:
-clean with detergent and
rinse thoroughly.


GOWNS




NEUBERS -- discovered cap and gown



Gowns, aprons, lab coats, clinic jackets,
should be worn when occupational exposure
is reasonably anticipated.



Long sleeve, high neck, cotton/polyester

garments are considered satisfactory
barriers.


Sleeves should be long enough so that gloves

fit securely over cuffs or end of sleeves.

ENVIRONMENTAL SURFACES


 May

become contaminated
 Not directly involved in infectious
disease transmission
 Do not require as stringent
decontamination procedures
 Clinical contact surfaces
High potential for direct contamination from
spray or spatter or by contact gloved hand


Housekeeping surfaces
Do not come into contact with patients or devices
Limited risk of disease transmission


Housekeeping Surfaces




Cleaning Clinical Contact Surfaces



Use barrier precautions (e.g., heavy-duty utility gloves, masks, protective
eyewear) when cleaning and disinfecting environmental surfaces



Physical removal of microorganisms by cleaning is as important as the
disinfection process



Do not use sterilant/high-level disinfectants on environmental surfaces



Cleaning Housekeeping Surfaces





Routinely clean with soap and water
Clean mops and cloths and allow to dry thoroughly before re-using
Prepare fresh cleaning and disinfecting solutions daily and per
manufacturer recommendations

SHARP ITEMS



Anesthetic needles, scalpel blades,
wires, endodontic files are considered
potentially infectious & handled with
caution to prevent injury.



Needles must not be bent, recapped, or
removed .



Contaminated needles should be placed
in leak proof, puncture resistant
containers with color coded biohazard
symbol.


PREVENTION OF NEEDLE STICK INJURIES


Ensuring that the needles and surgical blades are
sheeted, covered, when not in use.



Keeping full contact and retain full concentration while
handling such instruments



Adequate retraction of tissues



Over gloving or using double gloves whenever indicated


IMMEDIATE TREATMENT OF NEEDLE STICK INJURY








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 propylactic use of
azothymidine for needle stick injuries. but its value in the
prevention of HIV has not been proved.

HAIR




Hair should be kept out of field.
Hair can trap heavy contamination
Person must protect hair with a surgical cap when encountering
heavy spatter.




WASTE



WHO classified waste as follows
1.General non hazardous
2.Sharps
3.Chemical and pharmaceutical
4.Infectious and
5.Other hazardous medical waste


DISPOSAL


House hold non infective waste: collected in thick
polythene bags and discarded



Sharps: collected separately in puncture resistant
plastic containers and should be sealed securely



Infected hospital waste: collected in metallic containers,
decontaminated by autoclaving and disposed off at garbage
disposal sites.
It is done by following methods also:



Incineration – sophisticated method of burning the waste.



Deeply buried with bleaching powder and lime



Color coding

1.

Red:


-bags, buckets, containers

-dressings, gloves, other contaminated
material
2. yellow:
-bags, buckets, containers

-anatomical parts and lab waste

-biotechnological, microbiological waste, blood,
bloody fluids, bandages, soiled linen.

3.blue:
-bags in cardboard carton
-plastics, tubing, catheters, iv
sets, syringes without
needles.


-

WHITE

-

bags in cardboard
carton, containers
-glass bottles and vials

-


5.Red can:
-puncture proof, sharps container, cans, thick
cardboard boxes.
-needles, scalpels, surgical instruments.



STERILIZATION AND DISINFECTION REGARDING
MAJOR DENTAL PROCEDURES










Theatre washing and fumigation
Soap and water may be used
Then with 3% Lysol.
Fumigation is done with formaldehyde, and the formaldehyde
vapors are neutralized with ammonium hydroxide.
Theatre sterility test
After fumigation procedures, swabs are taken from potential
areas harboring clostridium tetani
swabs are incubated for a minimum of 10 days and then tested for
growth of clostridium tetani.
A negative report should be obtained. Three such consecutive
negative repots should be obtained to start a new operation
theatre.


OPERATING ROOM PROCEDURES
The ceiling,walls, and floors are regularly
disinfected,especially following a contaminated case.
 The operating rooms should have two sets of doors.
 The operating theatre should provide a safe, efficient
and a user friendly environment; being at the same
time, free from bacterial contamination, as far as
possible.
 The access to operation theatre and the recovery area
is restricted to operation theatre personnel, who are
required to don special scrub dress before entering
the operation room area.











• The scrub suit comprises of a pair
of pants/skirt/pyjama and a
shirt/blouse.
• A surgical cap is used to cover the
hair completely.
• A mask is then placed and tied
over the nose and mouth.
• Theatre shoes or shoe cover may
be used.


Once the patient is prepared and
draped, only those personnel, who have
scrubbed, gowned and gloved, may work at
the surgical site.
•
The backs of those who are gowned
are considered non-sterile, and also the
areas below the waist; unless the gowns are
long and back gowns are worn.
•
Hence, one must be careful to keep
the arms above the waist, when not
operating.
•
The masks and surgical cap are not
sterile, hence should not be touched.
•


FUMIGATION OF OPERATION THEATRES:
The operation theatres are disinfected by
fumigation.
The fumigation can be achieved by the use of
fumigators as well as potassium
permanganate reaction technique.
Fumigation is initiated after setting up of the
instrument(STERI TRAX) in place.

The chemical used in 40% formaline.
Fumigator is set for 30 mins.


Relative humidity(RH):
higher the humidity, better is the disinfection.
A minimum of 70% humidity is essential.
Temperature:
Evaporation of gaseous fumigant is more at the
higher temperature.
Formaldehyde levels in the air in the operation
theatre:
The dose of formalin is usually decided by the
size of the room. As a general rule, about 180 ml is
used for a room of the size 1000 cubic feet (= 10 x
10 x 10 feet).


Masks:
•disposable masks made of synthetic fibers are better; and
contain filters made of polyester or polypropylene.
•Surgical antifog masks with flexible nosebands are
available which follow facial contours and retain a high
efficiency of filtration.
•Masks provide protective function for wearer against
blood-borne viruses, as part of a policy of universal
precautions.

Hand Scrub Techniques


•
Hand scrub is the first step towards aseptic
surgical technique.
•
Wise et al (1959) have shown that 20 – 30 %
of surgeon’s gloves get punctured by the end of
operation.
•
Cole and Bernard (1964) have documented
the out pouring of bacteria from the surgeon’s
hands, through the punctured gloves into the
wound.
•
It is therefore imperative to have clean
hands inside the gloves.
•
The purpose of hand scrub is two-folds;
•
The first is to remove the superficial
contaminants and loose epithelium. This is achieved
from mechanical action of the brush.
•
The second purpose is to reduce bacterial
count on the skin. Ellis (1972) reported that use of
the iodophor scrubbing solution, results in the
effectiveness of the scrub in reducing the surface
bacterial count.


HAND SCRUBING (CONT.)











All jewelers be removed before washing.
The nails should be checked for cleanliness.
All gross sub nail contaminated should be removed.
The scrubbing begins at the tip of one finger of one hand.
The scrubbing is continued along the skin surfaces of
fingers and the interfinger webbing.
The scrubbing is continued until all the surfaces of the
hand are completed.
Then the hands are cleaned along the forearms and the
scrubbing is progressed towards the elbow, extending 2’’
above the elbow
In the similar manner the other hand is scrubbed beginning
at the fingertips and scrubbing towards the elbow.

•


A scrubbed area should not be
touched again because of the possibility
of contamination from an unscrubbed are.
•
Dunphey and Way (1973)
recommend that scrubbing procedure may
be done for approximately 10 mins. After
the scrubbing of both the arms the brush
is discarded and the arms are rinsed of
excess soap.
•
The rinse should be done with
arms elevated above the elbow
progressing down the arms and elbows.
The arms are not rubbed during the rinse.
•
The surgeon approaches the scrub
nurse for the sterile drying towel. The
technique of drying begins at the
fingertips of one hand progresses down
the arm. Then with the opposite side of
the towel, the other arm is dried in a
similar manner.


Hand disinfections.
•
There are some proprietary preparations
available for preoperatively washing of hands of
surgeons and assistant which have a bactericidal effect
and which do not cause excessive drying of skin.
•
Hibiscrub and phisomed contains 4 percent
chlorhexidine gluconate.
•
Betadine - contain 7.5 percent providone-iodine.
•
3% PCMX (Para chloro meta xylenol)
•
Soap containing disinfectants, like
hexachlorophene.
•
70% hibisol(2.5% chlorhexidine in 70%
alcohol) lotion may be applied.
•
Washing may be continued for 5 minutes in
running water. This is followed by drying of hands and
forearms.


PREPARATION OF THE SURGICAL SITE:
•
Hair in the area of surgery is removed, preferably, just
prior to scrubbing the skin.
•
Shaving the area the night before produces small
abrasions on the skin and resident bacteria multiply as a
result of injury.
•
This problem can be overcome by decreasing the time
interval between the shave and the skin preparation.
•
A lubricating ointment should be applied to patient’s
eyes, and they are covered.
•
The external auditory meatus is plugged and blocked,
if bleeding in the vicinity is anticipated.
•
The scrubbing should begin in the centre of the site to
be prepared, and move outward concentrically, away from
the site of operation.
•
This avoids contamination of already scrubbed site of
surgery.


DRAPING THE PATIENT:
The purpose of draping a patient is to isolate
the field of surgery from other parts of body
that have not been prepared for surgery, and
also from non sterile equipment and sterile
equipment.


ADDITIONAL PRECAUTIONS TO BE TAKEN INCASE OF H.I.V.
PATIENTS


If possible schedule surgery at the end of list



The team should be limited to essential members of staff and procedures to be
performed by experienced, fully trained staff.



Operator should wear
- 2 pairs of gloves
- plastic gown
- head cap

- mask
- protective eye wear


Procedures should be performed in a way, which minimizes the formation of
droplets, spatter and aerosols

- utilizing high volume aspirators
- rubber dams
- all surfaces inside the operatory and equipment should be thoroughly cleaned

ADDITIONAL PRECAUTIONS TO BE TAKEN
INCASE OF HBV PATIENTS















HBV is a stable DNA hydrophilic virus that can withstand drying
for more than 7 days
I milliliter of infected blood contains 1 billion virus particles
PRECAUTIONS
Proper medical history
2 pairs of gloves
Protective eye wear with solid side shield
Masks or face shields for heavy spatter
Disposable plastic gown
PEVENTION
HBV can be effectively prevented by vaccination. The vaccines
commonly used are Engerix – B , Recombivax - B
One dose followed by 2nd dose 1 month later and a 3rd dose 6
months later

ADVANCES IN DISINFECTION AND
STERILIZATION

Ortho-phthalaldehyde







It contains 0.55% 1,2-benzenedicarboxaldehyde.
Fast-acting high-level disinfectant
No activation required
Odor not significant
Claim of excellent compatibility with materials
Claim of not coagulating blood or fixing tissues to surfaces

Disadvantages






Limited clinical use
More expensive than glutaraldehyde
Eye irritation with contact
Slow sporicidal activity
Repeated exposure may result in hypersensitivity in some patients
with bladder cancer


Hydrogen peroxide gas plasmas
•They are generated in an enclosed chamber in a deep vacuum, by using
radio frequency or microwave energy to excite the gas molecules and
produce charged particles, many of which are in the form of free radicals.
• This process has the ability to inactivate a broad spectrum of
microorganisms, including resistant bacterial spores.

Disadvantages
•Cellulose (paper), linens, and liquids cannot be processed
•Sterilization chamber is small (∼3.5–7.3 ft3)
•Requires synthetic packaging (polypropylene wraps or polyolefin pouches)
or special container tray
•Hydrogen peroxide may be toxic at levels 11 ppm

Superoxidized water
The FDA recently cleared this liquid high-level disinfectant that contains
650–675 ppm free chlorine


Ozone enriched water
Ozone affects microbial membranes and denatures metabolic enzymes.
is an effective biocide against:
• Bio - Film
• Bacteria
• Viruses
• Fungi ( yeast, mold and their spores )
• Protozoa ( including cysts )

Antimicrobial Action
• Causes irreversible damage to the fatty acids in the cell membrane (e.g.
phosphatidylethanolamine) and cellular macromolecules, e.g. DNA.
• Biphasic death curve: an initial rapid inactivation stage followed by a slower
inactivation stage.
• 3000 times faster than chlorine
• Bactericidal effect on Salmonellae, Staphylococcus, E. coli, etc.
• Rapid and effective sporicide (Bacillus and Clostridium spores)


CONCLUSION

“Prevention is better than cure”. A proverb so well suited

to sterilization and asepsis. A thorough understanding
and application of the principles of sterilization will help
ensure safety from the invisible but deadly world of
microbial pathosis and assist the practitioner in
delivering holistic care with maximal efficiency ensuring

happy and healthy patients, personnel and physicians
themselves.


REFERENCES









Text book of microbiology--AnanthNarayan.
cedric, mim, hazel, m.docrell -medical microbiology
Text book of oral and maxillofacial surgery-laskin vol 1
Text book of surgery----Sabiston’s
Text book of oral and maxillofacial surgery---- Gustav. O .
Kruger.
Oral and maxillofacial infections-----Topazian, Goldberg, Hupp
Internet

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