INDIAN DENTAL ACADEMY
Leader in continuing dental education
KNOWLEDGE AND PRACTICE OF METHODS
USED FOR KILLING, REMOVING, OR
EXCLUDING MICROORGANISMS IS THE KEY
TO PREVENTION OF CROSS INFECTION IN
THE DENTAL CLINIC.
Process by which all forms of
viruses,bacteria fungi and spores over
articles or surfaces are destroyed.
Articles that are free of living organisms
are termed STERILE.
DEFINITIONS --•ASEPSIS-a condition free of germs from
infection &any form of life.
•DISINFECT-To free from infection by physical
or chemical means.
•DISINFECTION-Is used to describe a
process which reduces the number of
contaminating microorganisms particularly
those liable to cause infections,to a level
which is deemed no longer harmful to health.
•ANTI SEPSIS-a term used to describe
disinfectant applied to living tissue such as a
MODES OF TRANSMISSION
•FROM PATIENT TO PRACTITONER.
•FROM PRACTITONER TO PATIENT.
•FROM ONE PATIENT TO
ROUTE OF TRANSMISSION
INOCULATION –accidental self injury with a
contaminated needle,sharp insruments.
microorganisms transmitted –
HBV,HCV, HDV, HSV I ,HSV II, HIV,
NEISSERIA GONORRHOEA, TREPONEMA
PALLEDUM, CLOSTRIDIUM TETANI.
2. INHALATION :INHALATION OF MICROORGANISMS
AEROSOLIZED FROM A PATIENT’S BLOOD OR SALIVA
OCCURS WHEN USING HIGH SPEED OR ULTRASONIC
Eg :VARICELLA ZOSTER ,CYTOMEGALOVIRUS ,RUBEOLA
& MUMPS VIRUS ,RUBELLA VIRUS , MYCOBACTERIUM
TUBERCULOSIS, CANDIDA ALBICANS.
AREAS OF INFECTION CONTROL
•INFECTION CONTROL IN THE
•INFECTION CONTROL IN THE
LABORATORY SET UP.
INFECTION CONTROL IN CLINICAL AREA.
•PERSONAL PROTECTION EQUIPMENTS(PPE).
•ENVIRONMENTAL SURFACE CLEANING
•DISPOSAL OF WASTE.
CATEGORIES OF PERSONEL
•CAT 1-personnel routinely performs tasks that
involve exposure to blood or other potentially
•CAT 2-are personnel who on occasion may
perform tasks that involve exposure to blood
and other potentially infectious materials.
•Primary function- Protect worker from exposure to
•Minimal skin exposures,ie.long sleeves.
•Cuff of the sleeve covered by the band of the
•High risk procedures need have at least knee length when
•Buttons ,zippers,should be hidden and not exposed.
•Protective clothing not to be worn outside
the dental office.
•Change at least daily.
•Incase soiled, change immediately.
•Remove while relaxing esp. in the cafeteria
while eating or drinking.
Gloves should be used while touching ----
Blood and body fluids.
Non intact skin of the patient.
Items or surfaces soiled with blood or body
Types of gloves
Vinyl or latex sterile, single use surgical procedure.
Vinyl or latex - non sterile, single use examination procedure.
Rubber / plastic material - non
sterile,multiple use - over gloving.
Polyethylene - non-sterile,multiple use over gloving.
Nylon glove – non sterile ,multiple use –
using beneath gloves.
General precautions to be
taken while using gloves
Wear gloves for all dental procedures
Discard gloves whenever they have
Do not leave the clinic or walk around
Wash hands after removing gloves.
Used needles should not be recapped.
REPROCESSING OF GLOVES
Rinse your gloved hands thoroughly in a
Then in clear water to remove the disinfectant.
Wash with soap and water and rinse
Remove the gloves and hang them up by the
cuffs to dry
Dust glove powder on the inside of the gloves .
Test for holes in the house before reuse.
Autoclave the gloves.
Surgical masks / chin length plastic face
shields must be worn to protect the face.
Should have at least 95% filtration efficiency
for particles 3-5 micrometer in diameter.
Should be changed for each patient since its
efficiency decreases as it traps moisture
during dental procedures.
The eyes of a dental professional are
particularly susceptible to physical &
microbial injury by virtue of their
limited vascularity and diminished
Eyes must be protected during
operative procedures by spectacles.
AGENTS OF HAND CLEANING
•Substituted phenol preparations like
chlorhexidine gluconate and
•4% chlorhexidine & 3% PCMX are equally
•Both remain in the tissues in an active form for
prolonged periods thus maintaining a residual
activity for prolonged periods.
Method of sterilization
Moist heat (autoclaving)
(hot air oven)
•Moist heat denatures & coagulates the
protein of microbes.
•Better than dry heat because of its higher
efficiency of penetration.
•Due to latent heat of vaporization present in
TYPES OF AUTOCLAVES
POROUS LOAD AUTOCLAVES :
Autocycled high pressure vacuum models
Air is evacuated from the metal chamber
by vacuum suction.
1210 C , AT 20 lb pressure for 30 min.
Towels ,suture materials,cotton rolls,
rubber gloves ,root canal instruments.
SMALL BENCH TOP AUTOMATIC
Work on the principle of downward
displacement of air as a consequence of
steam entering at the top of the
Temp of 136oc ,at 32 lb pressure for 5
Less effective than moist heat
Higher temperatures ,longer periods &longer
heating up time required for sterilization (45 min
to reach 160oc).
Should have a time clock on the door ,so items
cannot be added or removed during the cycle & a
fan to distribute the heat evenly.
Combination of formaldehyde,alcohol,acetone,ketone &steam at
20 psi serves as an effective sterilizing agent.
biocidal action of formaldehyde depends on its alkylation of
microbial nucleic acids,which control protein synthesis.
Takes longer time than an autoclave (30 min)for packaged
instruments (shorter than hot air oven)
Advantage of chemiclave :
Lack of corrosion of instruments /burs.
Adequate ventilation must be provided
in order to expel the residual fumes
released on opening the chamber at the
end of the cycle.
Ethylene oxide gas
A flammable ,explosive and toxic gas to which
all types of microbes are susceptible.
Biocidal activity is due to alkylation and hence
causes denaturation of microbial nucleic acid.
Biocidal activity increases in the presence of
Plastic ,metal,rubber or cloth can be sterilized
Equipment is costly & gas is toxic.
STERILIZATION BY GAMMA
Used for needle,sutures ,gloves etc
GLASS BEAD STERILIZATION :
Heating glass beads in a chamber into
which instrument is inserted for 10-30
2100c –230 0c .
Suitable for very small instruments like
R.C.T instruments ,burs ,pliers etc.
•does not achieve sterilization as many spores
can with stand it.
•Cross infection from contaminated water
containing bacterial spores not killing by
PHYSICAL MONITORING :Refers to periodical observation of
displays or gauges on the sterilizer
during a cycle to ensure the sterilization
Two types are available
process indicators :- consist of colour
changing material (liquid /paper) which
changes color upon exposure to appropriate
TST strips (TIME ,STEAM,TEMPERATURE)
change color when all parameters have
been adequately achieved in the
Indicator used are heat resistant
bacterial spores (bacillus
If the spores are killed ,then less
resistant microbes are killed more
readily and sterility is achieved.
Classification of instruments to
Surgical other instruments used to penetrate
soft tissue / bone.
Should be sterilized after each use.
eg :-forceps ,scalpels,bone chisels,scaling
Instrument that do not penetrate soft tissue /
bone but contact oral tissues.
eg :-mirrors ,plastic instruments,burs etc.
Non critical :Items which do not come into contact
with body fluids.
eg:-light cure tips,glass slab,cement
Procedure before sterilization
•Pre soaking of instruments.
•Pre sterilization cleaning
•Keeps instruments wet.
•Prevents drying of saliva &blood on the
•Facilitating easy cleaning.
•solution used may be phenol or
Pre sterilization cleaning.
Ultrasonic cleaning :Employ piezo-electric oscillators situated underneath
S.S enclosures to create oscillations in a fluid filled
Oscillations are transformed into a series of high
frequency sound waves, which cause intense
microscopic cavitation in the fluid.
Large number of these tiny bubbles collapse creating
minute vacuum areas which are responsible for the
2 – 20 min
ADVANTAGE OF ULTRASONIC CLEANING
OVER MANUAL CLEANING
•Reduced danger of aerosolization.
•Reduced incidence of instrument injuries.
•Increased tarnish removal and cleanliness.
•Reduction in manual labour.
Fully closed system.(with individually
packed items in commercially available
Perforated trays.(with fitted covers wrapped
with sterilization paper)
Open tray system.(sealed with a see
through sterilization bag)
process of disinfecting instruments /
equipment by using a liquid chemical
germicide is called cold sterilization.
Used for heat sensitive instruments.
Aseptic rinsing with sterile water and drying
should follow this disinfection process.
Disinfectants used in dentistry
20 min. immersion in a 2% alkaline glutaraldehyde solution
6 -10 hours immersion – sterilization.
high biocidal activity.
Broad antimicrobial spectrum within 10-30 min.
Sporicial after 7-10 hrs. of exposure at room temperature.
Penetrates blood, pus & organic debris.
Induces severe tissue irritation upon prolonged contact.
Discolors nickel coated impression trays & carbon steel
Quaternary ammonium compounds.
Bactericidal against gram positive bacteria.
inactivated by organic matter.
Can sometimes support gram negative bacteria.
Easily inactivated by presence of anionic detergents, soaps
Rapid antimicrobial action.
Effective in dilute solution.
Sodium hypochlorite is useful as a broad spectrum
bactericidal, virrucidal, tuberculocidal surface
Disadvantage:•Sporicidal effects noted only at high
•Prepared solution has only limited shelf life.
•Activity diminished by presence of organic matter
& altered pH
Irritates skin &eyes.
Can degrade plastic & rubber coated instruments.
Instrument and environmental surface disinfectant
Rapid 3 min. disinfection ,6 hrs. sterilization.
Non-irritating and non-toxic.
Must be prepared daily
Does not readily penetrate organic debris.
Only 24 hrs shelf life.
Broad spectrum disinfectant, especially effective
against heavy viral contamination.
Biocidal activity occurs within 3-30 min.
Effective in dilute solution.
Not a sterilant.
Unstable at high temperature.
Must prepare daily.
Inactivated by hard water.
May discolor some light colored surfaces.
Alcohols (70% isopropyl alcohol &70%
Rapidly bactericidal against most gram positive & gram
Active against many lipophilic viruses
Ineffective against bacterial spores.
Diminished activity in organic matter and tissue debris.
Bactericidal activity diminished greatly.
They act as a protoplasmic poison which precipitate the
protein and destroy the cell wall.
synergistic effect instead of additive.
Broad antimicrobial spectrum.
Can be used on metal, glass, rubber &plastic.
Less toxic & corrosive.
Not a sterilant
No re-use life.
Irritates skin & eyes.
Two methods of surface asepsis.
• Cleaning & disinfecting the
• Preventing the surface from becoming
• Materials impervious to moisture.
• On surfaces difficult to clean.
• To be changed between patients.
(impervious- backed paper, aluminium foil /
plastic covers )
Spray – wipe spray technique.
• Spray the surface.
• Wipe in systematic pattern contacting each
surface at least twice.
• Spray again.
• Allow solution to dry and then wipe in 10
minutes for proper disinfection.
• The disinfectant used must be a hospital level
disinfectant ie.it should inactivate the Polio 2 virus and
Mycobacterium Tuberculosis .
• Isopropyl alcohol and quaternary ammonium
compounds are not recommended as they achieve less
level of surface wettability compared to that of water
Disinfecting dental equipments.
• Hand piece
• 3 way syringe tips
• HVE tips
• Most are autoclavable.
• Depends on manufacturers guidelines.
• Prior cleaning and lubrication is mandatory.
• Hand piece is placed in autoclavable pouch
with TST strips.
Steps for proper sterilization of hand pieces.
• Decontamination inside n outside.
• Rinse .
• Flush lines.
• Dry .
• Sterilize .
• Lubricate and run hand piece.
• Bag wrap.
Suck –back devices / check valves on hand pieces
Suck –back devices prevent any residual water left in
the line from the previous patient, from going into next
patient’s operating field when the procedure starts.
Check valve is a simple gadget that will tell you
immediately if any retained water is coming back out of
the hand piece.
Both these devices can be fitted on to an older hand
Three way syringe tips / high velocity
evacuation tips / aspirators
3 –way syringe should be treated in the same manner as
HVE tips –metal tips are autoclavable. Plastic tips must
be disposed off after single use.
Aspirators –disinfectant flushes for the aspirators should
be done after each patient.
Sterilization & disinfection of
Disinfection of dental impressions :ALGINATE:-iodophores / glutaraldehyde – 15 min.
LYSOL spray – 10 min.
ethylene oxide 4-12 hours
carbon steel instruments
chemical vapour---20 min at 270 °f
ethylene oxide ----4-12hours
dry heat oven---60-120 min at 320°f
tungsten carbide instruments
chemical vapour---20 min at 270 °f
dry heat oven---60-120 min at 320°f
Corrosion of instruments.
corrosion is an electrolytic process in which the contact of
two dissimilar metals sets up a potential difference
resulting in an electron flow.This flow leaves behind reactive
ions that readily combines with atmospheric oxygen to
form oxides (rust).
Corrosion resistance of orthodontic grade steel is directly
proportional to its carbon content and the chromium content
( PASSIVATION EFFECT)
Sterilization in orthodontics.
Plastic items & heat sterilizable
cheek retractors – immerse in procide
(strelalization solution whish turns milky after
Hand pieces & photographic mirrors – sterilized in a
Plier racks & instruments are placed in a wire basket
& run through an ultrasonic cleaner containing rust
inhibiting non-ionic multipurpose ultrasonic cleaner .
Ultra-sonic solution should be changed
daily & covered during cleaning to
Dried blood must be scrubbed off &
repeat ultrasonic cleaning .
Heavy duty nitril gloves are required for
handling contaminated instruments.
After cleaning instruments are dipped in
a sodium nitrite rust inhibitor
Auto clave for 20 min &20 min for
STERILIZATION OF NiTi WIRES
Heat sterilization is the most reliable method -
(Steam autoclaving at 1210C,15-20psi for 20
Chemical sterilization are corrosive &attack
metals immersed in them
(2% acidic Glutaraldehyde)
STERILIZATION OF ORTHODONTIC BANDS:-15 SECONDS OF
GLASS BEAD STERILIZATION.(SMITH et
al 1986 AJO)
CAUSES OF STERILIZATION
FAILURE (GEORGE 1993 JCO)
CYCLE TIME TOO SHORT
TEMPERATURE TOO LOW
FAILURE TO PREHEAT
INTERRUPTING OF CYCLE
OVERLOADING OF CHAMBER
INADEQUATE STAFF TRAINING
IMPROPER PRECLEANING, PACKAGING
FAILURE TO USE BIOLOGICAL INDICATOR
Disposal of waste
•Its should be disposed in tamper proof
•Its should be labeled as BIOHAZARD.
•Should be in tune with the existing laws of the
•Sharp material should be stored in hard walled
leak proof containers ,red in color.
Color coding for waste disposal
--- waste for incineration .
•Yellow with ---
waste for land fill .
•Light blue--- for autoclaving before disposal
---human anatomical wastes.
---normal household wastes.