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• CHAIN OF INFECTION
• MODE OF TRANSMISSION
• INFECTION CONCERN IN DENTISTRY
• PRINCIPLES OF INFECTION CONTROL
• OBJECTIVES OF INFECTION CONTROL
• PERSONAL BARRIER PROTECTION
• STORAGE OF STERILIZED ITEMS
• EMERGENCY & EXPOSURE INCIDENT PLAN
• CLINICAL WASTE DISPOSAL
• 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
• Infection control (IC) is an essential part of dentistry.
• Potential for disease transmission in the dental clinic and
lab is well documented.
• Potential pathogens can be transported to lab via orally
soiled impressions, dental prostheses/appliances.
• Microorganisms can be transferred from contaminated
impressions to dental casts.
• Oral bacteria can remain viable in set gypsum for up to 7
• INFECTION CONTROL – Also called “exposure control
plan” by Occupational Safety and Health Administration is a required
office program that is designed to protect personnel
against risks of exposure to infection.
• EXPOSURE – is defined as specific eye, mouth, other
mucous membrane, non intact skin, or parenteral contact
with blood or other potentially infectious
• STERILIZATION - Use of a physical or chemical procedure to
destroy all microorganisms including substantial numbers of
resistant bacterial spores.
• STERILE - Free from all living microorganisms; usually
described as a probability (e.g., the probability of a surviving
microorganism being 1 in 1 million).
• DISINFECTION: Destruction of pathogenic and other kinds of
microorganisms by physical or chemical means. Disinfection is less
lethal than sterilization, because it destroys the majority of recognized
pathogenic microorganisms, but not necessarily all microbial forms
(e.g., bacterial spores).
• DISINFECTANT: A chemical agent used on inanimate objects to
destroy virtually all recognized pathogenic microorganisms, but not
necessarily all microbial forms (e.g., bacterial endospores).
• Asepsis: Asepsis is the state of being free from disease-causing
contaminants (such as bacteria, viruses, fungi, and parasites). The term
asepsis also often refers to those practices used to promote or induce asepsis
in an operative field in surgery or medicine to prevent infection.
CHAIN OF INFECTION
• All links must be connected for infection to take place
& adequate numbers)
(allows pathogen to
survive & multiply)
from source to host)
(portal that the
enter the host)
(i.e., one that is not immune)
Mechanism for transfer of infectious
1) Cross contamination
2) Direct contact transmission
3) Indirect contact transmission
4) Droplet infection
5) Air borne infections
• Refers to spread of microorganisms from :
– One source to another
– Person to person
– Person to an inanimate object & then to another person
Direct contact transmission
• Infection is spread from
– one person to another without an intermediate object.
ndirect contact transmission
• Infection is spread from one person to another.
• By way of an environment surface / droplets / or other vehicle.
• Infection acquired by inhalation of droplets or aerosols that contain
microorganisms or viruses from another person.
• Term refers to :
substance / object that carries infectious material from one person to
another, directly or indirectly.
• The small particle of an aerosol have the potential to penetrate &
lodge in the smaller passages of the lungs & are thought to carry the
greatest potential for transmitting infections
(AEROSOLS & SPLATTER IN DENTISTRY; STEPHEN K. ET AL
JADA, 135, 429-437, APRIL 2004)
• A study conducted by Harrel et al on aerosol splatter from operative
field showed that the airborne material was spread for a distance of
atleast 18 inches from the operative site.
Site of entry into
Breaks in skin
Inhalation by dental
Through breaks in
skin of dental team
Gloves/ hand washing
Gloves ;hand washing
Instrument and hand
Flush water units
Use disposable items
Cuts in skin
Proper management of
Requirements of infection control
• For ideal cross infection control procedures:-
– Should be simple,
– Easily reproduced,
– Should not involve a great deal of surgery time,
– Should be easily understood by all staff,
– Should not involve toxic substances.
PRINCIPLES OF INFECTION
• PRINCIPLE 1- STAY HEALTHY
• PRINCIPLE 2- AVOID CONTACT WITH BLOOD
• PRINCIPLE 3- LIMIT THE SPREAD OF BLOOD
• PRINCIPLE 4- MAKE OBJECTS SAFE FOR USE
• PRINCIPLE 5- PATIENT SCREENING
PRINCIPLE 1- STAY HEALTHY
Sir William Osler tells “soap and water and
common sense are the best disinfectant”
OBJECTIVES OF INFECTION
To protect the patient and members of the dental team from contracting
infections during dental procedures
To reduce the numbers of pathogenic micro-organisms in the dental operatory
to the lowest possible level.
To implement a high standard of infection control when treating every
patient (universal precautions)
To simplify infection control, thus allowing the dental team to complete
treatment with minimal inconvenience.
STRATEGY TO ACHIEVE INFECTION
• All patients must be screened.
• Barriers for personal protection.
• Careful aseptic techniques.
• Sterilization & disinfection.
• Disposal of contaminated waste safely.
• Laboratory asepsis.
• Personal protective equipment (PPE), or barrier
precautions, are a major component of Standard
• PPE is essential to protect the skin and the mucous
membranes of personnel from exposure to infectious
• The various 5 barriers PPE are
1. Head cap
4. protective eye wear, &
5. over garments
• Hair should be neatly tied back and kept out of treatment field.
• should be covered with head cap to avoid hair contacting the
• If not covered the hair may act as a source of infection,
• Personnel must protect their hair with surgical cap while
encountering heavy spatter eg. Ultrasonic scaling device.
Face masks• Protective value
-to reduce post operative infection in patients caused by microorganisms in
respiratory tracts of surgeons,
- to protect the dentist from disease agents that might be present in sprays or
• Aerosols are airborne debris, smaller than 5ųm in diameter, that remain
suspended in air.
• Splatter are larger blood contaminated droplets which may contain sharp
• When airborne infection isolation precautions are necessary (e.g., for TB
patients), a National Institute for Occupational Safety and Health (NIOSH)-
certified particulate-filter respirator (e.g., N95, N99, or N100) should be
• Prevent inward and outward passage of microorganism,
• Filter particles produced during dental procedures,
• Have minimal marginal leakage.
Uses of masks
• any time there is risk or spraying or
splashing of fluids during patient care
• to protect against aerosol spatter.
N-95 MASK FOR TB
CAUSES OF EYE DAMAGE:
Aerosols and spatter may transmit infection
Sharp debris projected from mouth while using air turbine handpiece, ultrasonic
scaler may cause eye injury.
Injuries to eyes of patients caused by sharp instruments especially in supine
Therefore both the clinician and patients must use protective eyewear.
• Protective eyewear consists of glasses with solid eyeshields.
• Eyewear must be put on with clean hands before gloving and must be removed
after gloves are removed.
• Eyewear and shields must be cleaned and disinfected with water based
All clinical personnel must wear treatment
gloves during all procedures.
1. Latex gloves
2. Vinyl gloves
3. Nitile gloves
4. General purpose utility gloves
Latex gloves are the preferred operatory gloves.
Gloves manufactured by DOUBLE DIP process are
better than single dip because they have less pinholes
& use less irritating catalyzing coagulants.
• Gloves powdered using cornstarch or cetylpyridium chloride is better than
talcum powder (mineral) which may cause irritation.
• Medical gloves are manufactured as single-use disposable items that should be
used for only one patient, then discarded.
• Gloves should be changed between patients and when torn or punctured.
• Gloves must have < than 4% leak detectable by a water test.( FDA regulation)
• Utility gloves
– Heavy latex gloves
– Heavy or thin nitrile gloves
– Thin co polymer gloves
– Thin plastic gloves
• Other gloves
– Heat resistant gloves
– Dermal gloves
plastic glovesDermal gloves
• Offer little protection against injuries with sharp objects such as
instruments needle scalpel and blades.
• Precautions to be taken
-Clinical personnel must wear treatment gloves during all treatment
-If any leak detected, remove gloves wash hands and put on fresh gloves,
-Should not be washed with
hand soaps, reduces glove integrity.
- store them out of sunlight.
-should be tightly closed in heavy plastic bags, to minimize oxidation.
• Hypersensitivity to latex –true latex allergy or a reaction to
accelerators & antioxidants used in processing.
• Thiuram a chemical used in fabrication- reported to cause
allergic response. In march 1988- polyether component-
• Processing- during processing ammonia is added as a
preservative, which degrades the sap proteins to produce
• The final manufacturing process leaches the allergens from the
rubber products by soaking them in hot water. Leaching water
should be changed repeatedly to decrease the concentration of
• The rubber is hardened by the process of vulcanization i.e
addition of sulfur.
• Reports of hypersensitivity to latex products have increased in
oral health care workers since introduction of universal
precaution in early 1980s
(JADA Sep 1994, vol.125,
- dermatitis of hands and fingers
- 6-7%- surgical personnel- allergic
– use vinyl gloves
- synthetic polymer gloves.
• Worn to protect the skin and the clothing,
• Should be changed when ever moist or visibly
- light weight
-should cover arm, chest, up to neck and lap when seated.
- made of cotton/ synthetic fiber.
- thick enough to protect skin and street clothing
• Laundry done with regular detergent.
• Hot water up to 70ºc or cool water containing 50- 150ppm chlorine is used as anti
• Hand hygiene (e.g., hand washing, hand antisepsis,
or surgical hand antisepsis) considered the single
most critical measure for reducing the risk of
• The microbial flora of the skin, consist of transient
and resident microorganisms . Transient flora, which
colonize the superficial layers of the skin, are easier
to remove by routine hand washing.
• Resident flora attached to deeper layers of the skin are more resistant to
removal and less likely to be associated with such infections.
• For routine dental examinations procedures, hand washing is achieved by
using either a plain or antimicrobial soap and water.
• The purpose of surgical hand antisepsis is to eliminate transient flora and
reduce resident flora to prevent introduction of organisms in the operative
wound, if gloves become punctured or torn.
• Skin bacteria can rapidly multiply under surgical gloves if hands are washed
with soap that is not antimicrobial . Thus, an antimicrobial soap or alcohol
hand rub with persistent activity should be used before surgical procedures.
• At the beginning of a routine treatment period, watches and jewelry 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
• Clean brushes can be used to scrub under and around the nails.
• Must be repeated at least once to remove all soil.
• CHLORHEXIDINE BASED – these contain 2- 4% chlorhexidine
gluconate with 4% isopropyl alcohol in a detergent solution with a pH
of 5.0 to 6.5. They have broader activity for special cleansing(e.g: for
surgery, glove leaks, or when clinician experiences injury). But it can
be hazardous to eyes.
• POVIDONE IODONE – contain 7.5-10% povidone iodine, used as a
surgical hand scrub.
• PARACHLOROMETEXYLENOL(PCMX) – they are bactericidal and
fungicidal at 2% concentration. Non irritating and recommended for
• ALCOHOL HAND RUBS- ethyl alcohol and isopropyl alcohol are
widely used at 70% concentration. They are rapidly germicidal when
applied to the skin.
• According to the CDC (CENTRE OF DISEASE CONTROL),
patient-care items (e.g., dental instruments, devices, and
equipment) are categorized as critical, semi critical, or
noncritical, based on the potential risk of transmitting
infection if the item becomes contaminated during use.
Sterilization & Disinfection
Instruments that contact cut tissues or penetrate tissues are considered to be critical
items that require thorough cleaning and sterilization for reuse.
Forceps, periosteal elevators, cross bars
Scalpels, scissors, suture needles
Semicritical items that touch mucosa are the air/water syringe tip, suction tips, prophy
angle, and hand pieces. Others (air/water syringe handle etc) are handled or touched
interchangeably with treatment instruments that become contaminated with blood and
• Semi critical items must be removed for cleaning and sterilization
unless they are either disposable or can be protected from
contamination with disposable plastic covers.
• Noncritical items are environmental surfaces such as chairs,
benches, floors, walls, and supporting equipment of the dental unit
that are not ordinarily touched during treatments.
Light cure tips
Glass slab and cement spatula
• Contaminated noncritical items require cleaning and disinfection.
• Disinfection is a less effective process than
sterilization because it does not kill bacterial
• Disinfectants are antimicrobial agents that are
applied to non-living objects to destroy
microorganisms, the process of which is
known as disinfection
• Two functions:-
– Must be an effective antimicrobial agent,
– Must not adversely affect dimensional accuracy or surface
texture of impression materials and resulting gypsum cast.
• Want to reduce likelihood of ill fitting, nonfunctional
Criteria for an ideal disinfectant:-
Broad spectrum of activity
Is free of volatile organic compounds
Nontoxic, hypoallergenic & no staining
Good penetrating and cleaning ability,
Levels of disinfection:-
• High level- inactivates bacterial spores and all
forms of bacteria,fungi,and viruses depending on
contact time can be either a disinfectant or a
• Intermediate level- inactivates all forms of
microorganisms except spores,kills mycobacterium
tuberculosis var bovis.
• Low level – inactivates vegetative bacteria and
some lipophilic viruses but is not tuberculocidal or
• Hospital level disinfectant kills staphylococcus
aureus, pseudomonas aeurginosa and salmonella
CHEMICALS ADVANTAGES DISADVANTAGES
CHLORINES Rapid action
Prepare solution daily
Diminished activity by organic
IODOPHORES Broad spectrum
Residual biocidal activity
Unstable at high temperatures
Dilution and contact time critical
Prepare solution daily
Compatible with most
Degrades certain type of plastic
Difficult to rinse
Alchol base products are fair to
poor cleaning ability
• All disinfection procedures are accomplished prior to delivery to
• Done in dental operatory or professional work area.
• Recommend a sign and monitor system be implemented stating
“Only Biologically Clean Items Permitted”
• Rinse under running tap water to
• Disinfect as appropriate,
• Rinse thoroughly with tap water to
remove residual disinfectant,
• No single disinfectant is ideal or
compatible with all items &
• Annotate the DD Form 2322:
“Disinfected with ______ for _____minutes”
• Clean and disinfect before delivery
• After disinfection: rinse and place in
plastic bag with diluted mouthwash
• Do not store in disinfectant before
• Label the plastic bag: “This case
shipment has been disinfected with ______
for _____ minutes”
• Many studies have been performed to evaluate effects of
various disinfectants on different types of impression materials,
• Research findings have been contradictory,
• No single disinfectant is compatible with all impression
• The least distortion is associated with products having the
shortest contact times
• Many variables can affect impression materials:-
– Composition and concentration of disinfectants,
– Exposure time and compatibility of various disinfectants with
specific impression materials &
– Physical/chemical properties can vary in a given category of
material or disinfectant.
• Do an in-office “test run” when using new combinations of
impression materials and disinfectants.
• Consult dental materials’ manufacturers regarding their
compatibility with disinfectants
• The ADA recommends chemical disinfection of all impressions
and dental prostheses
An acceptable disinfectant is sodium hypochlorite
METHODS OF DISINFECTION
1.Spraying, Dipping &
• Exposure time should be that recommended by the
manufacturer of disinfectant for tuberculocidal disinfection.
• Iodophors, 5.52% sodium hypochlorite (1:10 concentration) with
minimum contact time of 10mins , chlorine dioxide, phenols,
and other approved products are all acceptable.
• Polyether materials cannot be immersed in disinfectants due to
potential for absorption and distortion.
• Immersion disinfectants can only be used once before
discarding (except for glutaraldehydes).
• Most reports indicate dimensional stability is not significantly
affected by immersion technique.
• Clean and rinse impression in dental operatory
– Cleaning efficiency can be improved by gently scrubbing
impression with camel’s hair brush and antimicrobial
• Sprinkle dental stone into impression before rinsing to aid in
• Cleaning and rinsing
– Reduces bio-burden present
– Lessens overall microbiologic challenge to disinfectant.
• Spray, dip, or immerse impression in appropriate intermediate-
or high-level disinfectant and place in sealed bag.
• Disinfection can be accomplished in the dental operatory or a
professional work area depending on facility policy &
• After required contact time, rinse impression and pour-up.
• Rinse entire impression/tray under running tap water after
removal from oral cavity.
• Trim excess impression material from noncritical areas
– Reduces number of microorganisms and organic debris
• Place impression in bag and liberally spray the entire
• Seal bag to create “charged atmosphere”
– Reduces exposure to vapors and liquid
• Remove from bag at end of exposure time; rinse and pour.
• Once stone has set, remove cast from impression.
• Dispose of impression material and disposable tray (if
applicable) in general waste &
• Sterilize reusable tray (if applicable).
– Uses less disinfectant,
– Same disinfectant can often be used to disinfect
– Probably not as effective as immersion,
– Can be released into air increasing occupational exposure.
• Select disinfectant with short exposure time to minimize
distortion and deterioration of surface quality of resulting stone
• Follow same procedures as above except fully immerse or dip
impression in disinfectant for recommended exposure time
• Do not use water based glutaraldehyde solutions with a pH of 8
or higher for since this might affect the gypsum surface.
• Very difficult to disinfect
• Cast should be fully set (at least 24 hours) before disinfection.
• Is preferable to disinfect impression.
• If casts must be disinfected:
– Place casts on end to facilitate drainage,
– Spray with iodophor or chlorine product, then rinse.
• Another option
– Soak casts for 30 minutes in 0.5% concentration of sodium
hypochlorite and saturated calcium dihydrate solution (SDS)
– SDS is produced by placing uncontaminated, set gypsum
(i.e. stone) in a container of water
ORALLY SOILED PROSTHESES
• Scrub with brush and antimicrobial soap to remove debris and
• Place prosthesis in sealable plastic bag or beaker filled with
ultrasonic cleaning solution or calculus remover.
• Place in ultrasonic cleaner for required time as specified by
manufacturer of ultrasonic cleaner .
• Place cover on ultrasonic cleaner to reduce spatter potential.
• Remove and rinse under running tap water, dry, and
accomplish required work.
• Place prosthesis in sealable plastic bag containing 1:10 dilution
of sodium hypochlorite or other intermediate- to high-level
disinfectant (not glutaraldeyde or phenols).
• Place in ultrasonic cleaner for 10 minutes
• Do not exceed manufacturer’s recommended contact time on
metal components to minimize corrosion.
• There is little effect on chrome-cobalt alloy with short-term
exposures (10 minutes).
• Do not store in disinfectant before insertion.
• Store in diluted mouthwash until insertion.
• Heat sterilize all metal and heat-stable
instruments that contact oral tissues,
contaminated appliances, or potentially
contaminated appliances after each use.
• Examples: facebow fork, metal impression trays, burs, polishing
points, rag wheels, laboratory knives
• Precleaning removes bio-burden and any adherent impression
• Ultrasonic cleaning can aid in removing residual set gypsum.
• Chrome-plated or aluminum trays
– Clean, package & heat sterilize.
• Single-use trays
– Discard after one use.
• Custom acrylic trays
– Can be disinfected (by spray or immersion), then rinsed (if to
be used for second appointment).
WAX BITES/RIMS, BITE
• Immersion disinfection may cause distortion to some items
– Use spray disinfection.
• Heavy-body bite registration materials
– Usually not susceptible to distortion and can be disinfected
in same manner as an impression of the same material
• Prosthodontic items contaminated by handling should be
disinfected (by spray or immersion technique based on type of
item) after each use.
• Examples: alcohol torch, facebow, articulator, mixing spatula,
mixing bowl, lab knife, shade/mold guide
CLEANING AND DISINFECTION
STRATEGIES FOR BLOOD SPILLS
• Strategies for decontaminating spills of blood and other body
fluids differ by setting and volume of the spill.
• The person assigned to clean the spill should wear gloves
and other PPE as needed.
• Visible organic material should be removed with absorbent
material (e.g., disposable paper towels discarded in a leak-
proof, appropriately labeled container).
• Nonporous surfaces should be cleaned and then
decontaminated with either an hospital disinfectant effective
against HBV and HIV or an disinfectant with a tuberculocidal
claim (i.e., intermediate-level disinfectant).
• However, if such products are unavailable, a 1:100 dilution
of sodium hypochlorite (e.g., approximately ¼ cup of 5.25%
household chlorine bleach to 1 gallon of water) is an
inexpensive and effective disinfecting agent.
• There are 4 distinct stages for instrument
1) Pre cleaning disinfection, using holding solutions
2) Pre – sterilization cleaning.
4) Aseptic storage.
The four accepted methods of sterilization are :
A. Steam pressure sterilization (autoclave)
B. Chemical vapor pressure sterilization- (chemiclave)
C. Dry heat sterilization (dryclave)
D. Ethylene oxide sterilization
• Patient load, turnaround time for instrument reuse, instrument
variety and quality must all be balanced against the type of
STEAM UNDER PRESSURE (AUTOCLAVING)
• Principle – it involves heating up of water to generate steam in a
closed chamber, producing a moist heat that rapidly kills microorganisms.
• As the steam is produced in a closed chamber it completely saturates the
sterilization chamber, replacing the cooler air and increasing the pressure.
• Saturated steam heats the article rapidly by releasing latent heat.
Condensation of steam and contraction leads to negative pressure on
Moist heat kills microorganisms through protein coagulation, RNA and
DNA breakdown and release of low molecular weight intracellular
Instruments made of alloys of carbon steel and tungsten carbide are
susceptible to corrosion during repeated autoclaving. The use of 2%
sodium nitrite solution coating minimizes such damage.
STEAM HEAT STERILIZATION
• Steam heat sterilization /autoclaving:
a) standard cycles –20-30min at 250
degree Fahrenheit under pressure 15
b)flash cycles –3-10min at 273 ºF
under pressure 30 pounds.
• Types of steam sterilizers :
– small office sterilizers
– hospital type sterilizers
Cycles in small office
• Heat up cycle
• Sterilization cycle
• De-pressurization cycle
• Drying cycle
1.THE HEAT-UP CYCLE
After the water is added the chamber is loaded, the door is closed and the
unit is turned on, and the heat up cycle begins to generate steam.
Steam pushes out the air in the chamber (called gravity air removal) and
when the set up temperature is reached, the sterilization cycle begin
2.THE STERILIZING CYCLE
Here the set temperature is maintained for the required period of time.
Typical pre- set sterilizing cycles are:
a)250 degree f – 30 min
b)250 degree f -15 min
c)273 degree f -10 min
d)273 degree f- 3 min
• At the end of sterilization cycle the depressurization cycle starts and the
steam is slowly released, with a decrease in temperature and pressure
4.THE DRYING CYCLE
• At the end of depressurization cycle all the items inside are wet.
• This cycle maintains heat inside the chamber to evaporate the remaining
water but the chamber is opened to the air so that the water vapour can
escape and the items can be dried.
• Some sterilizers have automatic drying cycles.
• With others, the door is simply opened about one-half inch for a time to let
the moisture escape.
• Advantages of Autoclaves.
Autoclaving is the most rapid and
effective method for sterilizing cloth
surgical packs and towel packs.
Is dependable and economical
Sterilization is verifiable.
• Disadvantages of Autoclaves.
Items sensitive to the elevated temperature cannot
Autoclaving tends to rust carbon steel instruments
Instruments must be air dried at completion of cycle.
Small office sterilizers
• Operates through four cycles :
Heat up cycle, the Sterilizing cycle, the Depressurization cycle,
the Drying cycle.
• Usual chamber diameter is 8-12 inches, may have a small
cassette containing the instruments that is inserted into the
• Some units also have printout devices that records the time and
temperature of each cycle to help maintain sterility assurance.
Hospital - Type Sterilizers
• Used in :Hospitals, Dental schools ,Large clinics.
• They have
– larger chambers ,direct connection to steam line ,or direct
connection to water line,
– vacuum system for air removal from the chamber
– post sterilization vacuum cycle that removes the steam and
water after the sterilization cycle.
• Loading –the manufactures instructions has to be strictly
• Sterilizing temperature-time ranges from 250-273 ºf ; 3-30 min.
Flash sterilization cycles
• Operates at 3 min at higher temperatures.
• 132 degree c at 30lbs pressure.
• 3 min for unwrapped & 7 min for wrapped items.
• Used only for emergency situations.
• Disadvantages are recontamination weakens sterility
• Kills the organisms and spores at lower temperatures in
• High penetrating power.
• Liquid and water solutions retain structure (sterilizes water
based liquids in standard cycles).
• It corrodes carbon steel instruments.
• Materials must be air dried at completion of the cycle.
• Heat sensitive materials can be destroyed.
CHEMICAL VAPOR PRESSURE
• The 1938 patent of Dr. George Hollenback and the work of
Hollenback and Harvey in 1940s culminated in the
development of an unsaturated chemical vapor system ,
also called Harvey Chemiclave.
• Principle is that although some water is necessary to
catalyze the destruction of all microorganisms in a
relatively short time, water saturation is not necessary.
• Kills microorganisms by destroying vital proteins.
• Chemical vapor pressure sterilizers operate at 270° F (131° C) and 20
pounds of pressure.
• They must be used with a prescribed chemical and should be properly
labeled to satisfy OSHA's Chemical Hazard Communication Standard.
• Unsaturated chemical-vapor sterilization involves heating a chemical
solution of primarily alcohol with 0.23% formaldehyde in a closed
Advantages of Chemiclaves
Carbon steel and other corrosion-sensitive instruments are said
to be sterilized without rust.
Relatively quick turnaround time for instruments.
Load comes out dry.
Sterilization is verifiable.
Disadvantages of Chemiclaves
Items sensitive to the elevated temperature will be damaged
Vapor odor is offensive, requires aeration.
Heavy cloth wrappings of surgical instruments may not be
penetrated to provide sterilization.
STERILIZATIONConventional Dry Heat Ovens
Dry heat sterilization is readily achieved at temperatures
above 320° F (160° C) for 30 mins.
Instrument loads may take 30- 90 mins to reach that
temperature, so to provide a margin of safety,
instruments must be sterilized at 160ºC for 2 hours.
They have heated chambers that allow air to circulate by
gravity flow (gravity convection).
Packs of instruments must be placed at least 1 cm apart
to allow heated air to circulate.
Kills microoragnisms primarily by an oxidation process. Protein
coagulation also occurs depending on the water content of protein.
High concentrations of mercury vapor can develop in a dry heat oven
that has been used to sterilize amalgam instruments. Thus great care
must be taken to scrap amalgam of any instrument.
• Short-Cycle, High-Temperature Dry Heat Ovens
It is a high-temperature process that uses a forced-draft
oven (a mechanical convection oven that circulates air with
a fan or blower)
It reduces total sterilization time to 6 minutes for
unwrapped and 12 minutes for wrapped instruments.
These short-cycle high-temperature dry heat ovens
operate at approximately 370° to 375° F .
• Advantages of Dry Heat Sterilization
Carbon steel instruments and burs do not rust, corrode, if they are well
dried before processing.
Industrial forced-draft hot air ovens usually provide a larger capacity at a
Rapid cycles are possible at high temperatures.
Low initial cost and sterilization is verifiable.
• Disadvantages of Dry Heat Sterilization
High temperatures may damage more heat-sensitive items, such as-
rubber or plastic goods.
Sterilization cycles are prolonged at the lower temperatures.
Must be calibrated and monitored
Glass bead sterlizer
• Working temperature- 218°c(424.4ºf)
• Working time –15s
• Pre heating time ranged from –15min to 3.5 hrs
• Disadvantages: Transfer of glass beads to the root canal,
resulting in blockage.
HOT SALT STERILIZER
• W.T- 218ºC.
• W.Time –10s.
• More safer than glass bead sterilizer.
• Pre heating required.
• Larger instruments should be immersed in for
ULTRASONIC CLEANERS AND
• Ultrasonic cleaning is the safest and most efficient way to clean sharp
• An ultrasonic cleaning device should provide fast and thorough cleaning
without damage to instruments; have a lid, well-designed basket, and
audible timer; and be engineered to prevent electronic interference with
other electronic equipment
• ultrasound (usually from 20–400 kHz)
• Operate the tank at one-half to three-fourths full of cleaning
solution at all times- Use only cleaning solutions
recommended by ultrasonic device manufacturers. Aqueous
cleaning solutions contain detergents, wetting agents and
• Operate the ultrasonic cleaner for 5 minutes or longer as
directed by the manufacturer to give optimal cleaning.
• Devices, that-have less than two transducers do not pass the
foil test and are not suitable for instrument cleaning.
ETHYLENE OXIDE STERILIZATION (ETO)
o Was first used in 1940’s by US army.
o Ethylene oxide sterilization is the best method for sterilizing complex
instruments and delicate materials because of extreme penetrability of the
ETO molecule and low temperature(70ºF- 140ºF).
o Kills microorganisms by reacting chemically with nucleic acids. The basic
reaction is alkylation of hydroxyl groups.
o It is a gas at room temperature (B.P 10.8ºC).
o Alkalizing agent, exerts lethal affect on proteins of bacteria.
o Uses- nearly all material whether metal , plastic, rubber or cloth.
o Highly inflammable (mixed with carbon dioxide)
o Well ventilated room necessary.
o Time 2- 12 hrs ( depending on temp and concentration)
Operates effectively at low temperatures
Gas is extremely penetrative
Can be used for sensitive equipment like handpieces.
Sterilization is verifiable
Potentially mutagenic and carcinogenic.
Requires aeration chamber ,cycle time lasts hours
Usually only hospital based.
• Heat-sensitive critical and semicritical instruments and
devices can be sterilized by immersing them in liquid
chemical germicides registered by FDA as sterilants.
• Items need to be
– 1) rinsed with sterile water to remove toxic or irritating
– 2) handled using sterile gloves and dried with sterile
– 3) delivered to the point of use in an aseptic manner.
• They can kill bacterial spores in 6 to 10 hours.
• Sterilants used for high-level disinfection of items for reuse are
glutaraldehydes at 2% to 3% concentrations which kills by
altering essential protein components.
• Glutraldehyde molecules has two active carbonyl groups which
react with proteins through cross linking reactions.
• High-level disinfection is used mainly for plastic items that enter
the mouth and that cannot withstand heat sterilization like plastic
cheek retractors and photographic mirrors.
• Disadvantages include prolonged time taken, irritating to skin &
cannot be monitored with biological indicators.
NEW METHODS OF STERILIZATION
Various new methods of sterilization are under
investigation and development.
1. 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
2. Ultraviolet light - exposes the
contaminants with a lethal dose of energy in
the form of light. The UV light will alter the
DNA of the pathogens. Not effective against
RNA viruses like HIV. The optimum wavelength for
UV sterilization is 260 nm
STORAGE OF STERILIZED
• The storage area should contain enclosed storage for
sterile items and disposable (single-use) items.
• Storage practices for wrapped sterilized instruments can
be either date- or event-related
• Dental supplies and instruments should not be stored
under sinks or in other locations where they might become
Principles And Procedures For Handling And
Cleaning Instruments After Treatment
• The safest and most efficient instrument cleaning procedures
involve ultrasonic cleaning of used instruments kept in a perforated
basket or cassette throughout the cleaning procedure.
• Wear protective utility gloves at all times to handle contaminated
• Organic debris on instruments is likely to reduce activity of the
• Used instruments are commonly placed in an anti microbial solution
as this softens and loosens debris.
• Next, move the or basket of instruments into an ultrasonic
cleaning device, rinse them, and then carefully inspect the
instruments for debris.
• Dip instruments likely to rust into a rust inhibitor solution.
Drain & dry instruments with absorbent towel.
• Still wearing protective gloves, properly package the
instruments together with internal and external sterilization
indicators suited to the sterilization process use.
• Cloth packs, wraps, or commercial paper/plastic bags are
suitable for instrument containment if they are compatible
with the method of sterilization.
• Engineering controls are the primary method to reduce
exposures to blood from sharp instruments and needles.
• Work-practice controls establish practices to protect
personnel whose responsibilities include handling, using,
or processing sharp devices.
• Work-practice controls for needles and other sharps include
placing them in appropriate puncture-resistant containers
located as close as feasible to where the items were used.
• Sharp end of instruments must be pointed away from the
• Work-practice controls include removing burs before
disassembling the handpiece from the dental unit,
restricting use of fingers in tissue retraction during suturing
and administration of anesthesia, and minimizing
uncontrolled movements of sharp instruments.
• Used needles should never be recapped or otherwise
manipulated by using both hands, or any other technique
that involves directing the point of a needle toward any part
of the body.
• A one-handed scoop technique, a mechanical device
designed for holding the needle cap to facilitate one-handed
recapping, or an engineered sharps injury protection device
(e.g., needles with resheathing mechanisms) should be
employed for recapping needles.
• Personnel should never bend or break needles
before disposal because this practice requires
POST EXPOSURE PROPHYLAXIS
Management of exposure includes:
A. General wound care and cleaning.
B. Counseling of the exposed worker regarding blood borne
C. Source patient testing for HBV,HCV and HIV (consent
D. Documentation of the incident and review.
E. Post exposure assessment and prophylaxis for the health care
IF AND THEN
Source pt is
Exposed worker not
Worker should receive
should receive single
dose of HB
immunoglobulin within 7
Exposed worker has
Should be tested for anti-
HBs & given 1 dose of
vaccine & 1 dose of HBIG
if < 10 IU
IF AND THEN
is –ve for
Worker should be encouraged to
receive hepatitis B vaccine.
No further action is needed.
Should receive HB series
HBIG should be considered
Management should be
IF THEN AND
Source pt has
Source pt is
Source Pt refuses
to be tested
Exposed worker should
be counseled about risk of
Should be tested for HIV
Should be asked to seek
medical advice for any
febrile illness within12
Refrain from blood
donation & take
be retested 6
weeks & 6
IF THEN AND
Source pt is
tested & found
testing of the
be done &
Regulated medical waste is only a limited subset of waste: 9%-15% of
total waste in hospitals and 1%-2% of total waste in dental offices.
Examples of regulated waste found in dental-practice settings are solid
waste soaked or saturated with blood or saliva (e.g., gauze saturated
with blood after surgery), extracted teeth, surgically removed hard and
soft tissues, and contaminated sharp items (e.g., needles, scalpel
blades, and wires.
• Regulated medical waste requires careful containment for treatment or
• A single leak-resistant biohazard bag used for containment of non
sharp regulated medical waste.
• Puncture-resistant containers with a biohazard label- used as
containment for scalpel blades, needles, syringes, and unused sterile
• All containers with blood or saliva (e.g., suctioned fluids) can be
carefully poured down a utility sink or drain.
• Adding 5% hypochlorite in water to suctioned fluids is recommended
before disposing into the drain.
• Multiple bloodborne pathogens, are not stable in the environment for
long periods, and the discharge of limited quantities of blood into the
sanitary sewer is considered a safe method for disposing of these
OPTION WASTE CATEGORY TREATMENT&
CATEGORY 1 HUMAN TISSUE,ORGANS,BODY
CATEGORY 2 ANIMAL WASTE INCINERATION/DEEP
CATEGORY 3 MICROBIOLOGY &
CATEGORY 4 WASTE SHARPS CHEMICAL
CATEGORY 5 DISCARDED MEDICINES &
DISPOSAL IN SECURED
CATEGORY6 SOLID WASTE (ITEMS
CATEGORY7 SOLID WASTE(WASTE GENERATED FROM
DISPOSIBLE ITEMS OTHER THAN WASTE
SHARPS SUCH AS TUBINGS,CATHETER)
CATEGORY8 LIQUID WASTE(WASTE
GENERATED FROM LAB
CHEMICAL TREATMENT &
CATEGORY9 INCINERATION ASH DISPOSAL IN MUNCIPAL
CATEGORY10 CHEMICALS USED IN
AND DISCHARGE INTO
DRAINS FOR LIQUID &
SECURED LANDFILL FOR
COLOR CODING & TYPE OF CONTAINER FOR DISPOSAL OF BIO-MEDICAL
• Properly labeled containment to prevent injuries and leakage.
• Medical wastes are “treated” in accordance with state and local EPA
(Environmental Protection Agency) regulations.
• Processes for regulated waste include autoclaving and incineration.
Tips for protecting dental
• Clean as soon as possible to remove corrosive materials such
• Keep instruments from knocking against each other as much
as possible during the cleaning process.
• Do not store for longer period of time in water or chloride
• Only use cleaning solutions that are recommended for dental
or medical instruments.
• Rinse well after cleaning.
• Use distilled or deionised water in steam sterilizers to avoid
water spotting of instruments and damage to sterilizer.
• Use rust inhibiters for carbon steel items.
• Dry items prior to processing through dry heat or chemical
• As we have discussed lots of infections & preventive
methods , which will make sure the safety for both the
doctors & patients.
• So, it is the duty & responsibility for each & every doctor and
a technician to follow the infection control protocol such as
sterilization & disinfection methods in order to protect the
patients from contagious disease & microorganisms
1. The art & science of operative dentistry- Sturdevant.
2. Textbook of microbiology – Davis & panikar
3. Textbook of hospital dentistry-Harold.a.Black
4. Davidsons principles and practice of medicine
5. Practical Infection Control in Dentistry -James A. Cottone
6. CDC. Guidelines for infection control in dental health-care settings – 2003.
MMWR 2003; 52(No. RR-17):1–66. Available at
7. Infection Control Cover Story JADA VOL.134, MAY 2003.
8. Textbook of medical microbiology – Gupte.