Personal contact: Diseases spread from one person to other by direct contact.Carrier contact: Any person who harbours a pathogenic microorganism without getting the disease himself is considered as carrier.Droplet: It occurs when the person breathes, talks, sneezes or coughs.Indirect transmission:Occurs through dirty hands, soiled laundry articles, contaminated instruments or anything touched during the dental procedures.
Which can reduce the risk of exposure of the DHCW’s skin or the mucosal membrane to potentially infective materials. In 1996, CDC has expanded uni prec to other aspects of disease transmission and renamed it as “standard precautions. “
[essential for both patient and dentist.]
sterilisation in Dentistry /certified fixed orthodontic courses by Indian dental academy
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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
bacteria and microscopic fungi.
They may be pathogenic or non
pathogenic, present on both animate and
They are divided into
a) Vegetative bacteria
b) Sporulating bacteria
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
Sepsis:- Refers to presence of infection, infectious
material or agent.
ASEPSIS:- It is the prevention of contact with
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
Bacteriostatic:- These agents prevent the
multiplication of bacteria.
METHODS OF STERILIZATION
Hot air oven
steam under normal and
Ultrasonic and Sonic
The purpose for which the sterilization is carried out
→ Materials which has to be sterilized
→ Nature of microorganism that are to be removed
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
Spontaneous sterilization under natural conditions.
Limited clinical utility.
Moisture is essential for bacteria
Drying therefore has a deleterious effect on most bacteria.
Viruses are more resistant
Spores are unaffected
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
Hot air oven
Most primitive of all methods
Used for sterilization of Innoculating
loops or wires, points of forceps and
The instruments are held in a bunsen
flame till they become red hot
Burs dipped in alcohol & flammed 2 or
This is an excellent method
for safely destroying materials
such as contaminated cloth,
animal carcasses and
Plastic like PVC and
polythene can also be
HOT AIR OVEN
Widely used method of
sterilization by dry heat.
Temperature:160 c- 170 c (320 –
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.
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.
materials except silicone rubber will not withstand
1. Preserves the sharpness of
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
Rapid heat transfer sterilizer
Operates at 370-375 F (190 C).
Sterilization time 6 minutes for unwrapped ,and 12 minutes for
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
Not suited for hollow instruments
Temperature at 100 c
Steam under pressure
Steam at atmospheric
TEMPERATURE BELOW 100C
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
veg. bacteria – 90 – 100 c
spores – prolonged periods of boiling
Add 2% sodium bicarbonate to water ( increases the
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
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
STEAM UNDER PRESSURE
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.
Saturated steam has penetrating power & when it comes in
contact with cooler surface it condenses & gives latent heat to
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.
It is expressed in terms of psi (pound per square
inch) or kpa (kilo Pascal's: kpa = 0.145psi).
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.
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
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.
cotton rolls, rubber gloves etc.
2. Small portable bench model type
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
Accepted dental therapeutics (1977)
recommends use of dicylohexylammonium
nitrate or cyclohexylamine and decylamine.
Bertocoltti and hurst (1978) recommend 2%
WRAPPING INSTRUMENTS FOR
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
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
CASSETTE WRAPPED IN
POROUS AUTOCLAVE PAPER
INSTRUMENTS IN SURGICAL PACK
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
Steam is removed & dry heat is introduced from outside
into the cabinet for 15 mins.
1. Short efficient cycle time.
2. Good penetration.
3. Ability to process a wide
range of materials.
1.Corrosion of unprotected carbon
2.Dulling of unprotected cutting
3.Possibility that packages may
remain wet at end of cycle.
4.Possible deposits from use of hard
5.Possible destruction of heat
6.Heat & moisture may act overtime
to dull & rust instruments,
weaken certain plastics &
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
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
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.
Dry instruments are available after cycle.
Long aeration period required.
Adequate ventilation required.
Chemical hazards possible.
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
They are 2 types:
Unglazed ceramic filters - Chamberland & Doulton
Diatomaceous earth filters - Berkfeld & Mandler
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.
Routinely used in water purification and
analysis, sterilization and sterility testing
The preparation of solutions for parenteral use.
Two types of radiation are used for sterilization purpose
Nonionizing radiation – U.V.Rays, Infrared rays
- X-Rays , Gamma Rays, Cosmic Rays
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
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
Safest way to clean sharp instruments.
Effective up to 9 times more than hand cleaning
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
E.g.: methyl alcohol, ethyl alcohol, isopropyl alcohol
Methyl alcohol is effective against fungal spores
To treat cabinets & incubators affected by fungus
Cabinets & chambers are wiped with methanol
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.
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.
Active against amino group in protein molecule
Bactericidal & sporocidal, lethal against viruses
To preserve anatomical specimens
Destroys anthrax spores in hair & wool
10 % formalin + 1/2 % sodium tetra borate used to sterilize clean metal
Formalin gas is used to sterilize instruments & heat sensitive catheters, to
fumigate wards, sick room & labs,Clothing, bedding, furniture & books
Gas is irritant & toxic when inhaled
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
Used as skin & wound antiseptics
Bacteriostatic on high dilution but low bactericidal
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
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.
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 &
Antibacterial spectrum is similar to alcohols.
Limited to Gm+ve & some Gm-ve organisms.
Not effective against spores, viruses, mycobacterium
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.
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
If mixed with carbon dioxide and nitrogen explosive tendency is
MODE OF ACTION:
Acts by alkylating the amino, carboxyl, hydroxyl and sulfhydryl groups
in protein molecules and also reacts with DNA & RNA
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.
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
Condensed product of ketone & formaldehyde with boiling point
of 163 c
Low penetrating power but more efficient for fumigating purpose
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
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
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
ARTICLES AND METHOD OF STERILIZATION
Hot air oven
Boiling at 100 c
Suture materials except catgut
Bone and tissue grafts,
adhesive dressings, Implants
Dressings, Aprons, Gloves,
Chlorine as hypo chlorites
Tincture iodine, savlon, spirit
PROCEDURES BEFORE www.indiandentalacademy.com
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
Storage: After sterilization the instruments are stored in a central
Sterilization area should be well separated to avoid probable
CAUSES OF STERILIZATION FAILURE
Improper cleaning of instruments
Improper temperature in sterilizer
Improper loading of sterilizer
Improper timing of sterilization cycle
STEPS TO BE TAKEN AFTER STERILIZATION
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
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
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
Surface asepsis of dental instruments
achieved by two methods:
By cleaning and disinfecting
Preventing the surface from becoming
contaminated by use of surface cover.
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
2)Pathogen with sufficient infectivity and numbers to cause
3)Portal through which the pathogen enters the host
AN INFECTION TO OCCUR REQUIRES ALL
THE FOLLOWING CONDITIONS TO BE
WHY IS INFECTION CONTROL IMPORTANT
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
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.
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
Eg: hepatitis B is an occupational hazard for dental personnel , on
the other hand there are evidences of dentists transmitting
PATHWAYS OF CROSS INFECTION
Patient to practitioner
Practitioner to patient
Patient to patient
Clinic to community
Clinic to practitioners family
Community to patient.
2. Means of
1.Source of infection:
-a patient ,member of
in the blood,
-contact with blood or
saliva mixed with blood
one person to another.
3.Route of transmission:
-accidental injury with a
Ex: hepatitis, herpes simplex,
-aerosols and splatter.
Ex: CMV, varicella zoster,
mycobacterium tb, streptococcus
pyogenes, candida, rubella.
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.
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
It occurs when the person breathes, talks, sneezes or coughs.
Eg: common cold, flu.
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
Identification of the infected patients by medical history,
physical examination or lab tests for each and every
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
Exposure prevention and post exposure management
Medical condition management and work-related
illnesses and restrictions
Health record maintenance
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
Washing hands with plain soap and water
Washing hands with water and soap or other detergents containing an
Rubbing hands with an alcohol-containing preparation
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
Most Frequently missed
Less Frequently missed
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.
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
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
Change the masks every hour or
change for every patient.
Masks covering mouth and nose
minimize inhalation of aerosol &
protects the mucosal
Types: cone, ear loop & surgical
95% of filtration efficiency in
presence of 3-5 micrometer
EAR LOOP MASKS
CHARACTERISTICS OF IDEAL MASK
No contact with the wearers
lips and nostrils
Has a high bacterial filtration
No fogging of eye wear
Made of material that does not
Does not collapse during wear
or when wet
Plastic foam, fiber glass, synthetic fiber
-grip side elastic or tie strings to
contaminated mask with gloved or
Never place the mask under the chin.
-to avoid eye infections.
-contamination can be introduced
from saliva, biofilm, carious
cavity preparations, bacteria
laden calculus during scaling
and any other microorganisms
-wide coverage, with wide
shields, to protect around
strong, sturdy plastic
smooth edges to prevent
against the nose or ears.
-eyewear with side shields
-eyewear with curved
-post mydriatic spectacles
-clean with detergent and
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
Sleeves should be long enough so that gloves
fit securely over cuffs or end of sleeves.
Not directly involved in infectious
Do not require as stringent
Clinical contact surfaces
High potential for direct contamination from
spray or spatter or by contact gloved hand
Do not come into contact with patients or devices
Limited risk of disease transmission
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
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
Anesthetic needles, scalpel blades,
wires, endodontic files are considered
potentially infectious & handled with
caution to prevent injury.
Needles must not be bent, recapped, or
Contaminated needles should be placed
in leak proof, puncture resistant
containers with color coded biohazard
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
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 should be kept out of field.
Hair can trap heavy contamination
Person must protect hair with a surgical cap when encountering
WHO classified waste as follows
1.General non hazardous
3.Chemical and pharmaceutical
5.Other hazardous medical waste
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
It is done by following methods also:
Incineration – sophisticated method of burning the waste.
Deeply buried with bleaching powder and lime
-bags, buckets, containers
-dressings, gloves, other contaminated
-bags, buckets, containers
-anatomical parts and lab waste
-biotechnological, microbiological waste, blood,
bloody fluids, bandages, soiled linen.
-bags in cardboard carton
-plastics, tubing, catheters, iv
sets, syringes without
bags in cardboard
-glass bottles and vials
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
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
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
• A surgical cap is used to cover the
• A mask is then placed and tied
over the nose and mouth.
• Theatre shoes or shoe cover may
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
The masks and surgical cap are not
sterile, hence should not be touched.
FUMIGATION OF OPERATION THEATRES:
The operation theatres are disinfected by
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.
higher the humidity, better is the disinfection.
A minimum of 70% humidity is essential.
Evaporation of gaseous fumigant is more at the
Formaldehyde levels in the air in the operation
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).
•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
Hand Scrub Techniques
Hand scrub is the first step towards aseptic
Wise et al (1959) have shown that 20 – 30 %
of surgeon’s gloves get punctured by the end of
Cole and Bernard (1964) have documented
the out pouring of bacteria from the surgeon’s
hands, through the punctured gloves into the
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
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
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
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
Betadine - contain 7.5 percent providone-iodine.
3% PCMX (Para chloro meta xylenol)
Soap containing disinfectants, like
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
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
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
ADDITIONAL PRECAUTIONS TO BE TAKEN INCASE OF H.I.V.
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
- 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
Proper medical history
2 pairs of gloves
Protective eye wear with solid side shield
Masks or face shields for heavy spatter
Disposable plastic gown
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
ADVANCES IN DISINFECTION AND
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
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.
•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
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
• Fungi ( yeast, mold and their spores )
• Protozoa ( including cysts )
• 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
• 3000 times faster than chlorine
• Bactericidal effect on Salmonellae, Staphylococcus, E. coli, etc.
• Rapid and effective sporicide (Bacillus and Clostridium spores)
“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
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 .
Oral and maxillofacial infections-----Topazian, Goldberg, Hupp