Sterilization in dental operatory

 Sterlization
Autoclave
Chemiclave
DryclaveDryclave
ETOX
 New methods of sterilization
 Dental control unit water system & hand
piece asepsis
 Sterilization of handpiece & related
rotary equipment

Disinfectant/detergent/enzymatic
product solution is used.
Function:
1. Keeps fresh debris from drying
2. Softens & loosens any dried debris

 Two cleaning methods are used:
1) Hand scrubbing
2) Mechanical cleaning
( e.g Ultrasonic Cleaner )

 Increases accidental puncture through direct
handling of sharp instruments

Safest and more effective way to clean sharp
instruments.
Keep the tank filled 1/2- 3/4th the total height with an
ultrasonic cleaner solution.ultrasonic cleaner solution.
Timer set usually is
› 5 minutes : loose instruments
› 15 minutes: instruments within cassette.
Solutions should be replenished
as directed (usually 3 days)

Physical Chemical
Method Method

 SUNLIGHT- possesses appreciable
bactericidal activity, under natural
condition, due to its content of UV rays.
 Heat Dry
Moist

Dry Heat
Flamimg
Moist
Heat
Boiling
Incineration
Hot air oven
Pasteurization
of milk
Autoclave

 Flaming -Flame of bunsen burner is
employed for few seconds-
Bacteriological loop, Scalple, Needle.
 Incineration- excellent method for
rapidly destroying materials. Eg : soiled
dressing, bedding & pathological
material, hospital gowns.

Conventional dry heat ovens
 Circulates air by gravity flow(gravity convection)
 Operate at 160˚C for 30 min
 Foil wraps or special nylon bags are used Foil wraps or special nylon bags are used
Short cycle, high temperature dry
heat ovens
 Circulate air with fan or blower
 Operates at : 180 ˚C
12 min (wrapped instruments)
6 min ( unwrapped instruments)

Advantages
 Carbon steel instruments and burs do not rust, corrode, or lose
their temper or cutting edges if they are well dried before
processing.
 Rapid cycle at high temperature
Disadvantages
 May damage rubber or plastic goods
 Cycles are prolonged at lower temperature
 Cycles are not timed automatically

1) AT A TEMPERATURE OF 100°C:
Boiling- Immersion in boiling water is first of
several moist methods that shall be
considered.considered.
 Minimum exposure period must be 30 min.
 Vegetative bacteria are killed at 90- 100
degree, but sporing bacteria requires long
time.
 Cutting instruments are made dull by
repeated boiling.

2) AT A TEMPERATURE BELOW 100°C :
Pasteurization of milk- its purpose is to
reduce bacterial population of a liquid
such as milk.
 Destroys all non sporing pathogens.
 Heating at 63°C for 30 min Heating at 63°C for 30 min
 Heating at 72°C for 15 sec followed by
cooling quickly to 13°C
Vaccine bath-are sterilized in special
vaccine baths at 60°C for 1 hr.

2 cycles utilized:
1. 121˚ C/15psi/15 min
2. 134 ˚C/30 psi/7 min
Advantage:Advantage:
1. Most effective method for cloth surgical pack & towel
packs.
2. Sterilization can be monitored
Disadvantage:
1. Items sensitive to elevated temp cannot be sterilized.
2. Carbon steel instruments tend to rust.

Operate at 131 ˚C/ 20 pounds/30 min
Advantage
› Carbon steel & other corrosion sensitive burs, instruments & pliers
are said to be sterilized without rust.
› Items dry quickly after cycle
Disadvantage:
› Damage items sensitive to elevated temperature
› Load only dry instruments
› Towels and heavy cloth wrappings of surgical instruments are not
penetrated.

2 cycles utilized:
1. 121˚ C/15psi/15 min
2. 134 ˚C/30 psi/7a min
Advantage:Advantage:
1. Most effective method for cloth surgical pack & towel
packs.
2. Sterilization can be monitored
Disadvantage:
1. Items sensitive to elevated temp cannot be sterilized.
2. Carbon steel instruments tend to rust.

5. Place any loose sharp instruments and instrument
cassettes into a perforated metal basket, and then
lower the basket into disinfectant solution in a
covered hard-walled pan. Return the air/water
syringe tip, handpieces, and pan of instruments tosyringe tip, handpieces, and pan of instruments to
the cleanup area. Using handles provided, remove
the basket of instruments, rinse, and then place
into the ultrasonic cleaner.

Immediate sterilization between patients
Preheating is required
Endodontic instrumentsEndodontic instruments
(broaches(broaches--reamersreamers--files)files)
218˚ C for 15 seconds

 It is a process related to removal of microorganisms and
microscopic particles to a specific size level from solutions to
produce a product that is considered to meet set guidelines for
that particular product.
 The modern day application involves sterilization of IV fluids,
irrigation solutions for surgery,irrigation solutions for surgery,
 Various filters used for the purpose of sterilization are:
a) CANDLE FILTERS:
These are manufactured in different grades of porosity and have
been used widely for purification of water for industrial and
drinking purposes. They are of two types namely ceramic filters
and diatomaceous earth filters.

b) ASBESTOS FILTERS:
They are disposable, single use discs. They have high
adsorbing capacity and tend to alkalize filtered liquids. But
their carcinogenic potential has discouraged their use.their carcinogenic potential has discouraged their use.
Example seitz and sterimat filters.
c) SINTERED GLASS FILTERS:
They are prepared by heat fusing finely powdered glass
particles of grades sizes. They have low absorptive property
and can be cleaned easily but are brittle and expensive.

d) MEMBRANE FILTERS:
They are made of cellulose esters or other polymers. They
have largely replaced other type of filters. They arehave largely replaced other type of filters. They are
routinely used in water purification and analysis, sterilization
and sterility testing, and for preparation of solutions for
parenteral use.
They come in a wide range of average pore diameters, the
0.22 micro meter size most widely used for sterilization.

 Hot oil baths have been used to sterilize
metallic instruments such as handpieces.
 15 minutes of submersion in preheated oils to
a temperature of 175°c is necessary for
sterilization.sterilization.
 Oil has poor penetration properties, poor
sporicidal activity, presents a fire hazard & is
difficult to remove from instruments without
recontamination.
 It also poses danger of oil embolisation if
accidentally used on hypodermic syringes or
needles.

Two types-
i) Ionising radiations- γ rays,X rays, cosmic rays.
 Have high penetration power.
 Damage DNA
 γ rays- for disposable items – plastic syringe, swabs,
culture plates, catheters.culture plates, catheters.
ii) Non-Ionising radiations-infra red , UV rays
 Infra red- rapid mass sterilization for syringe, catheter
 UV rays-wavelength 240-280 nm ( bactericidal
activity)
 UV rays used for inoculation hoods, operation
theaters.
 Vegetative bacteria susceptible to UV rays & spores
highly resistant.

 Cleaning programme should be simple and clearly
laid out policy which can be adhered to.
 Daily cleaning should be carried out after the
operating sessions are over.operating sessions are over.
 All the surfaces should be cleaned with detergent
and water and may be wiped over with a phenol if
any spills with blood / body fluid are present.
 All the walls must be wiped down to hand height
everyday.

 The floors should be scrubbed with warm water and
detergent and dried. No disinfectant is necessary.
 The O.T. table and other non clinical equipments must
be wiped to remove all visible dirt and left to dry.
 Weakly cleaning of all the areas inside the operating
theatre complex should be done thoroughly with warm
water and detergent and dried.
 The storage shelves must be emptied and wiped over,
allowed to dry and restacked.

Procedure for fumigation:
 The windows should be sealed and formaldehyde
should be generated either by boiling a solution of
formalin 40% or by adding it to potassium
permanganate, in a metal vessel on the floor, since
heat is also generated. The door is than closed andheat is also generated. The door is than closed and
scaled.
 For a 10 x 10 x 10 ft room - 150 gm potassium
permanganate and 280 ml of formalin are used

Duration:
 In case of any construction in O.T.  48 hrs
 In case of inflected cases  24hr
 For routine clean cases  12 hrs. For routine clean cases  12 hrs.
 Alternatively 250 ml of formalin and 3000 ml of tap
water are put into a machine (auto mist) and time
is set for 2 hrs. The mist is circulated for 2hrs inside
the closed room.

 Room is kept sealed for another 2 hrs for action of
vapor. Ventilate for suitable time for vapor to
dissipate. Room then can be used.
 Three swabs are taken from walls, all equipments, Three swabs are taken from walls, all equipments,
floor or O.T. table at intervals.
 1st swab - 48 hrs after fumigation
 2nd swab- 24 hrs after Is' swab
 3rd swab - 12 hrs after 2"d swab

 All three consecutive swabs should come
negative.
 In some centres, Bacillocid is being used for
fumigation. It is combination of chemically boundfumigation. It is combination of chemically bound
formaldehyde and glutaraldehyde.
 Ideally all O.T. rooms should be fumigated once a
week

 A variety of chemical agents are used as
antiseptics and disinfectants.
 Characteristics of an ideal antiseptic or disinfectant
are:are:
1. It should have wide spectrum of activity and be
effective against all microorganisms including
bacteria (both vegetative and spore forms ),
viruses, protozoa and fungi.
2. It should act in the presence of organic matter
3. Have high penetration power and quick action.

4. It should be stable and effective in acidic as well as
in alkaline conditions.
5. It shouldn’t corrode metals
6. It should be compatible with other disinfectants
7. It should not cause local irritation and shouldn’t be
toxic if absorbed into circulation.
8. It should be easily available and cheap too.8. It should be easily available and cheap too.

 Ethanol ( ethyl alcohol) and isopropyl alcohol are
more frequently used as antiseptics.
 Alcohols possess some antibacterial activity Alcohols possess some antibacterial activity
against some gram positive bacteria and
especially against M. Tuberculosis.
 They act by denaturing bacterial proteins.
 They are not effective against spores and viruses.

 Mainly used as skin antiseptics and to be
effective they should be used at a
concentration of 60- 70% in water, as
water speeds up the denaturing process.
 Methyl alcohol is effective against fungal
,spores and is used for treating cabinets.
 Carbon steel instruments shouldn’t be
soaked in alcoholic solutions, as they are
corrosive to carbon steel.

FORMALDEHYDE-
It is a broad spectrum antimicrobial agent used for
disinfection.
- Used as bactericidal,sporicidal, virucidal.
- used as both aqueous solution and in gaseous form.
-It is a hazardous substance, flammable and irritant to-It is a hazardous substance, flammable and irritant to
the eye, skin and respiratory tract.
 Used at upto 50 degree Centigrade and is used for
large heat sensitive equipments, e.g. ventilators,
suction pumps, excluding rubber and sore plastics
 Preservation of tissue for histological examination

 To sterilize bacterial vaccines.
 To prepare toxoid from toxin.
 For killing bacterial cultures and suspension.
 GASEOUS FORM-
 Expelled into closed chamber ,as sterilizing
agent for surgical equipment, hospital
gowns & medical instruments.gowns & medical instruments.
 Penetration is poor.
 Exposed to gas for 12 hours for effective
sterilization.

GLUTERALDEHYDE-
Disinfectant which is less toxic and irritating to tissues.
 Active against most vegetative bacteria(including
M. Tuberculosis) and some viruses including HIV and
,fungi and bacterial spores. used where heat can’t be,fungi and bacterial spores. used where heat can’t be
used and is used As 2% buffered solution
 commercially available as cidex…
 requires 20 mins immersion for disinfection and 6-10 hrs
for sterilization.

Uses: Sterilization of cytoscopes,
endoscopes and bronchoscope.
-Sterile plastic endotracheal tubes, face-Sterile plastic endotracheal tubes, face
masks, corrugated rubber anaesthetic
tubes and metal instruments

 CHLORHEXIDINE-
It is active against number of
bacteria including staphylococcus aureus
and some gram –ve bacteria but not
spores, viruses and fungi.spores, viruses and fungi.
- can be mixed with alcohol or with
cetrimide .
 It gets inactivated in the presence of soap,
pus, plastics etc.

 Mainly used for cleaning skin and
mucous membrane.
 Chlorhexidine with cetrimide ( savlon or
Cetavlon) or 4% solution with detergent(Cetavlon) or 4% solution with detergent(
hibiscrub) as a preoperative scrub.
 As a 0.2% aqueous solution or 1% gel, it
can be used for suppression of plaque
and post operative infection.

MODE OF ACTION:
They are oxidizing agents and cause damage by oxidation of
essential sulfydryl groups of enzymes. Chlorine reacts with
water to form hypochlorous acid, which is microbicidal.water to form hypochlorous acid, which is microbicidal.
Examples: Chlorine compounds (chlorine, bleach, hypochlorite)
and iodine compounds (tincture iodine,
iodophores)

 Applications: Tincture of iodine (2% iodine in 70%
alcohol) is an antiseptic. Iodine can be combined
with neutral carrier polymers such as
polyvinylpyrrolidone to prepare iodophores such aspolyvinylpyrrolidone to prepare iodophores such as
povidone-iodine.

 An effective germicide.
• Was used as a disinfectant for the irrigation of
wounds before the availability of antibiotics.
 Used for disinfection of instruments and linen Used for disinfection of instruments and linen
especially after surgery on HIV positive patients.
 0.5% sodium hypochlorite is used in serology and virology.
Used at a dilution of 1:10 in decontamination of spillage of
infectious material.

 Its concentration for use in endodontics
today varies from 0.5% to 5.25%. At low
concentrations it will dissolve mainly
necrotic tissue; whereas at highernecrotic tissue; whereas at higher
concentrations tissue dissolution is better
but it also dissolves vital tissue, a generally
undesirable effect…..

Iodines:
 Used as skin disinfectant in aqueous and alcoholic
solution.
 Active bactericidal with moderate action against Active bactericidal with moderate action against
spores.
 Active against M.Tuberculosis and viruses.
Disadvantage-corrosive and staining

IODOPHORS:
 In these compounds iodine is complexed with
organic surface active agents e.g. – betadine
 Their activity depends on release of iodine from this Their activity depends on release of iodine from this
complex.
 These compounds build up on the skin after
successive scrubs which provides long lasting anti
bacterial activity.

 They are produced by distillation of coal tar
between temp.of 170- 270 degree centigrade.
 They are active against Fungi and bacteria but They are active against Fungi and bacteria but
not spores.
 1% phenol has bactericidal action

 Mode of action: Act by disruption of membranes,
precipitation of proteins and inactivation of
enzymes.
 Examples: 5% phenol, 1-5% Cresol, 5% Lysol Examples: 5% phenol, 1-5% Cresol, 5% Lysol
(a saponified cresol), hexachlorophene,
Chlorhexidine, chloroxylenol(Dettol)

 Chlorhexidine can be used in an isopropanol solution for
skin disinfection, or as an aqueous solution for wound
irrigation. It is often used as an antiseptic hand wash.
 20% Chlorhexidine gluconate solution is used for pre-
operative hand and skin preparation and for general skin
disinfection.
 Chlorhexidine gluconate is also mixed with quaternary
ammonium compounds such as cetrimide to get
stronger and broader antimicrobial effects (eg. Savlon).

 Disadvantages: It is toxic, corrosive and skin
irritant.
 Chlorhexidine is inactivated by an
ionic soaps. Chloroxylenol is inactivated byionic soaps. Chloroxylenol is inactivated by
hard water….

 CRESOLS, CHLOROXYLENOL are commonly used
as antiseptics.
 CRESOL- Lysol is a solution of cresolin soap. CRESOL- Lysol is a solution of cresolin soap.
- mostly used for sterilization of infected glass wares,
cleaning floors, disinfection of excreta..
 CHLOROXYLENOL: As active ingredient of dettol.
Less toxic and less irritant

 Extensively used dyes :
i). Aniline
ii). Acridineii). Acridine
 Both are bacteriostatic in high dilution
but low bactericidal activity.

 MODE OF ACTION: Acridine dyes are bactericidal because of
their interaction with bacterial nucleic acids.
 Examples: Aniline dyes such as crystal violet, malachite green
and brilliant green.and brilliant green.
 Acridine dyes such as Acriflavine and aminacrine. Acriflavine
is a mixture of Proflavine and euflavine. Only euflavine has
effective antimicrobial properties.
 A related dye, ethidium bromide, is also germicidal.
 They are more effective against gram positive bacteria than
gram negative bacteria and are more bacteriostatic in action.

 BENZALKONIUM CHLORIDE (zephiran):
Effectiveness of these compounds depends on
strength, activity and duration of contact used
both as an antiseptic and disinfectant.both as an antiseptic and disinfectant.
 Its antibacterial spectrum is similar to alcohols,
except it is not effective against M. Tuberculosis.
 It is a strong surfactant that increases the
permeability of bacterial wall and permits the
escape of phosphorous & nitrogen.

1)FORMALDEHYDE- used for fumigation
2)ETHYLENE OXIDE (ETOX)-
Gas at temp. above 108 degree C is highly penetrative,
non- corrosive agent with a cidal action against
bacteria, spores and viruses.bacteria, spores and viruses.
MODE OF ACTION- Destroys microorganisms by alkylation
and causes denaturation of nucleic acids microorganisms.
- Has potential toxicity to human beings Including mutagenicity
and carcino- genicity.

Uses:
1) Excellent sterilizer of heat Sensitive items. i.e. hand piece
2) Ideal for electric equipments flexible fibers, endoscopes
and photographic equipments.

 Advantages:
 1) Penetrates well, even going through
plastics.
2) Can be used at low temperatures.2) Can be used at low temperatures.
3) Leaves no residue.
4) Is a deoxidizer and is non toxic.
5) Many heat sensitive articles,
e.g. plastics & rubber can be
sterilized.

 Disadvantages :
1) High cost of
Equipment.
2) Toxicity of gas.2) Toxicity of gas.
3) Explosive and
inflammable.
4) Longer period of
aeration. 90 min.

Done by:
Sterilization indicator & date-
 Sterilizers have printout tapes which does this automatically.
 Mechanically monitored- document time, temperature &
pressure.
 Mechanically monitored- document time, temperature &
pressure.
 Indicators include- tapes & bags marked with heat sensitive dye
that changes color on exposure to heat, pressure & sterilization
chemical.
Chemical indicator strip-
 Chemical on strip changes color slowly, relative to temperature
reached in packets.
 Pack is opened, strip can identify immediately breakdown &
gross overloading.

Biological monitoring strip-
 Spores are dried on absorbent paper strip & calibrated to kill
all pathogenic microorganism.
 Monitored weekly.
Documentation notebook-
 One affixes a single, dated, initialed indicator strip to a
calendar for each workday ,followed by weekly spore strip
report.

After autoclaving, instruments have to be stored
in a dry, protected area.
To maintain the sterilization, Ultraviolet Sterilizers are
recommended.
Before usage, pouches are transferred to the
dental chair.

 High and low-speed handpieces – best autoclaved.
Ethylene oxide-450-800 mg/I.Ethylene oxide-450-800 mg/I.
Steam autoclave- 121°C for 15 to 20 minutes at 15 lb
 Burs – can be safely sterilized by
(i) Dry heat or
(ii) Chemical vapor in a Chemiclave or in a Gas Sterilizer
(iii)Burs and instruments used in opening pulp chamber are
sterilized in alcohol and flamed 2-3 times.

 Impression trays, Aluminum metal tray-
Chemical vapour- at 270° F for 30 minutes
Ethylene oxide-450-800 mg/l.
Metal impression trays – by any method, but dry heat above
3450F may remove soldered handles .345 F may remove soldered handles .
 Glass slabs
Dry heat oven-160°C for 1 hour,
Chemical vapour- 270° F for 30 minutes
Ethylene oxide-450-800 mg/l.

Hand instruments
Carbon steel
 Dry heat oven-l60°C for 1 hour,
 Chemical vapour- 270° F for 30 min
 Ethylene oxide450-800 mg/l.
Stainless steel
 Steam autoclave- 121°C for 15 to 20 minutes at 15 lb
 Dry heat oven-I 60°C for 1 hour,
 Chemical vapour- 2700 F for 30 min
 Ethylene oxide-450-800 mg/l.
Needle
 Discard; do not reuse

Mirrors (mouth &face)
 Ethylene oxide-450-800 mg/l
 Dry heat oven
 Tissue Retraction Pluggers
 Dry heat over-160°C for 1 hour,
 Ethylene oxide-450-800 mg/I.
 Polishing wheels and disks

 Saliva Evacuators, Ejectors
 Ethylene oxide-450-800 mg/l.
 Stones
 Chemical vapour-270° F for 30 minChemical vapour-270° F for 30 min
 Water- Air syringe tips
 Dry heat oven-l60°C for 1 hour

 Orthodontic pliers –
high quality stainless steel will resist corrosion in an autoclave:
lower quality stainless steel – sterilized by dry heat or chemical
vapor.
 Towels and towel pack of instruments needed for surgery -
best sterilized by autoclaving.
 Reamers and files and other endodontic instruments
immersed for 5sec for sterilization in glasss beads sterilizer and
10sec to sterilize in absorbent points and cotton pellets.

 Gutta Percha cones kept sterile in alcohol and before use insert in
5.25% Naocl for 1min and rinse with H2O2 and dry it with sterile
gauge.
 Silver cone are sterilized in dry heat by passing 3 – 4 times. Silver cone are sterilized in dry heat by passing 3 – 4 times.
 Dappen dish and other glassware are sterilized by
 Steam autoclave-121°C for 15 to 20 minutes at 15 lb
 Ethylene oxide-450-800 mg/l
 Bulky instrument, like cottonpliers, cement spatulas are sterilized by
passing threw the flame.

 Burs can be protected by keeping them
submerged in a small amount of 2 % sodium nitrite
solution.
 Normal sterilization cycle is operated.
 Sterile forcep is used to place bur into a sterilized
bur holder/tray.
 Burs are stored dry.

DENTALDENTAL CONTROLCONTROL UNITUNIT WATERWATER SYSTEMSSYSTEMS ANDAND
HANDPIECEHANDPIECE ASEPSISASEPSIS
 Hand piece surface contamination control
Only sterilization can approach complete infection control
of handpiece surfaces.
 Turbine contamination control
Operating the handpieces between patients to flush the
handpiece is prescribed to reduce this risk.

 Water retraction system correction
Since 1988, nearly all manufacture have manufactured
dental control units that simply cut off the water spray
without retraction.
 Inherent water system contamination
Clean water reservoir systems combined with disinfection
or sterilization of equipment downstream have been
developed by at least 2 companies ( ADEC, Portland,
Oragon). Always remove the handpiece before
disinfecting the system.
Disinfectants – iodophore or diluted sodium hypochlorite
are use. Clean, boiled, sterile water must be flushed.

ELIMINATION OF MICROORGANISMS FROM DENTAL
OPERATORY COMPRESSED AIR
 A device called Puril Air has been devised that
heats every particle of inflowing compressed air toheats every particle of inflowing compressed air to
2500C and then forces it through a fine-pore
ceramic filter.

Sterilization in dental operatory

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