A detailed version of all the latest sterilization and disinfection strategies followed in all dental settings in recent times.

1. Dr. Jasmine Vinshia
Assistant Professor
Department Of Microbiology
Rajas Medical Institutions
Sterilization & Disinfection in Dental Office

2. • Terminologies
• Need for sterilization and disinfection
• Techniques of sterilization(brief)
• Recent advances in sterilization
• Biological controls for different sterilization methods
• Commonly used sterilization methods in dental office
• Sterilization of various surgical instruments
• Effect of sterilization on instruments
• Newer disinfectants

3. • Sterilization: It is defined as a process by which
article, surface or medium is freed of all living
micro-organisms either in vegetative or spore
state.
• Disinfection: The destruction or removal of all
pathogenic organisms, or organisms capable of
giving rise to infection.
• Asepsis: It is the state of complete
absence of viable pathogens in any environment.

4. • Antiseptics: They are agents that can be safely applied on the skin or
mucous membrane to prevent infection by inhibiting the growth of
bacteria.
• Bactericidal agent/ germicides: They are substances that can kill
bacteria.
• Bacteriostatic agents: They prevent the multiplication of bacteria which
may, however, remain alive.
• Decontamination: It is the process of rendering an article or area free of
contaminants, including microbial, chemical, radioactive and other
hazardous materials from an area, object or body surface.
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5. • The oral cavity being an ideal source of nutrition harbors bacteria and viruses from the nose,
throat and respiratory tract as well.
• Any dental procedure that has the potential to aerosolize saliva will cause airborne
contamination
• Since pathogenic microorganisms cause contamination, infection and decay, it becomes
necessary for the dentists to take appropriate precautions to protect their patients , their staff and
more importantly THEMSELVES from the risk of cross-infection.
• All hospitals need to sterilize their equipment and supplies. Even the smallest private clinic
requires sterile surgical instruments for minor procedures, and sterile dressing materials.
• If a hospital has a full surgical unit, the sterilization of surgical instruments and linen, together
with dressing materials for the wards and operating theatre, plays a key role in infection control.
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6. • Physical methods
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1) Sunlight
2) Drying
3) Dry heat: Flaming, Incineration, Red heat, Hot air oven
4) Moist heat: Vaccine Bath, Inspissation, Pasteurization,
steam under normal pressure,
steam under pressure(Autoclave)
5) Filtration: Candles, Asbestos, Membranes, Syringe, Sintered
6) Radiation
7) Ultrasonic and sonic vibration
F I R H
V I P
C A M S 2

7. Recent advances in sterilization
• Plasma sterilization: Plasma is known as the
fourth state of matter and consists of ions, electrons
or neutral particles. A radio frequency energy is
applied to create an electromagnetic field.
• Into this, hydrogen peroxide vapors are introduced
which generates a state of plasma containing free
radicals of hydrogen and oxygen.
• This state renders the articles sterile by
denaturing all microorganisms.
Arthroscopes, urethroscopes, etc., are sterilized
by this method.
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8. Flash sterilization
• Flash sterilization was originally defined by Underwood and Perkins as
sterilization of an unwrapped object at 1320°C for 3 minutes at 27-28
lbs. of pressure in a gravity displacement sterilizer.
• Flash sterilization is considered acceptable for processing cleaned
patient-care items that cannot be packaged, sterilized, and stored before
use.
• It also is used when there is insufficient time to sterilize an item
by the preferred package method.

9. Ultrasonic Vibrators
• Used instruments are soaked into a container
containing 70% isopropyl alcohol for removal of
organic debris. After removing instruments rinse
thoroughly in warm water to remove all
chemicals.
• As a final step insert the instruments into the
ultrasonic vibrator and operate for 30 minutes,
after which sterile instruments are rendered.
• Ultrasonic vibrators are generally used for
non-critical items.
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10. BIOLOGICAL CONTROLS FOR DIFFERENT
STERILIZATION METHODS
METHOD OF
STERILIZATION
BIOLOGICALCONTROL
Hot Air Oven Bacillus subtilis subsp. Niger
Clostridium tetani
Autoclave Bacillus stearothermophilus
Filtration Serratia marcescens,
Pseudomonas diminuta
Ionizing Radiation Bacillus pumilis 29

11. The four accepted methods of sterilization in dental offices
are:
 Steam pressure sterilization (autoclave)
 Chemical vapor pressure sterilization(chemiclave)
 Dry heat sterilization(dryclave)
 Ethylene oxide(ETOX) sterilization
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12.  It is performed in a steam autoclave. For light load of instruments
the time required at 121o C is 15 minutes at 15lbs of pressure. It
works on principle as that of pressurecooker.
Advantages: rapid and effective.
Disadvantages: items sensitive
Tends to rust carbon steel instruments and burs.
Sterilization of burs in autoclaves.
burs can be protected by keeping them submerged in small amounts
of 2% sodium nitrite solution.
Steam pressure sterilization(autoclave)
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13.  Performed in a chemiclave.
Operate at 131oC and 20lbs of pressure. they are similar to steam
sterilizer and have cycle of 30minutes.
•carbon steel and other corrosion sensitive instruments and pliers
are sterilized without rust or corrosion.
• items sensitive.
The 1938 patent of Dr. George Hollenback and the work of
hollenback and harvey in 1940s culminated in the developmentof
an unsaturated chemical vapor system , also called harvey
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Chemical vapor pressure sterilization
chemiclave.

14. Advantages
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1. Carbon steel and other
corrosion-sensitive instruments
are said to be sterilized without
rust.
2. Relatively quick turn around time
for instruments.
3. Load comes out dry.
4. Sterilization is verifiable.
Disadvantages
1. Items sensitive to the
elevated temperature will be
damaged. Vapor odor is
offensive, requires aeration.
2. Heavy cloth wrappings of
surgical instruments may not
be penetrated to provide
sterilization.

15.  Conventional dry heat ovens
 Short cycle, high temperature dry heat oven.
They have heated chambers that allow air to circulate by
gravity flow.
A rapid high temperature processing that uses forced draft
oven(air circulates witha
fan or blower)
Operate at approximately 188oC-191oC
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Dry heat sterilization

16. Advantages
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1.Reasonable price
2.carbon steel instruments and
burs do not rust or corrode or lose
temper or cutting edges.
3.Rapid cycles possible at high
temperatures
Disadvantages
1.rubber and plastic materials
might damage.
2.heavy load of instruments
defeats sterilization.
3.Improper calibration may
damage instruments

17. Etox sterilization is the best method for sterilizing complex
instruments and delicate materials.
Advantages
 Operates effectively at low temperatures
 Gas is extremely penetrative
 Can be used for sensitive equipment like handpieces.
 Sterilization is verifiable
Disadvantages
 Potentially mutagenic and carcinogenic.
 Requires aeration chamber ,cycle time lasts hours
 Usually only hospital based.
Ethylene oxide sterilization
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18. OPERATORYASEPSIS
 In the dental operatory, operatory surfaces that are
repeatedly touched or soiled are best protected with
disposable covers(barriers)that can be discarded after
each treatment.
 For dental unit trays, paper, plastic film or surgical pack
wraps (paper or towels) should cover the entiretray.
 Clear plastic 15-gallon waste container bags fit many
chair backs , control units , and x-ray equipment.
 Plastic restaurant silverware bags it suction handles and
air water syringe handles.
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19.  Gigasept which contains succindialdehyde and
dimethoxytetrahydrofuran are used for disinfection of
plastic and rubber materials eg: dental chair
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20. Asepsis of surgery theaters
 Fumigation is done by two methods:
1. Electric boiler method- 500 ml of formaldehyde
(40%) added to distilled water in electric boiler.
When the water heats fumes are generated.
2. Potassium permanganate – heat is induced by
oxider action of potassium permanganate. 500ml
of formaldehyde is added to potassium
permanganate which reacts and generates fumes.
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21. DENTALRADIOGRAPHY
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• Contamination of working area occurs from saliva.
• X-ray tube head, exposure selector and timer button are likely to get
contaminated by saliva.
• Precaution to be taken up :
1. Put on gloves.
2. Place the film packets and film holders in special tray.
3. Contaminated films(exposed films) to be placed in separate tray.

22. 4. Film holding device to be rinsed in running
saliva.
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water to remove
5. Metallic part to be autoclaved.
6. Plastic attachments to be kept in chlorhexidine solution.
7. Wipe the x-ray tube head, exposure selector, timer button and film
packets with detergents.
8. Tube can be wrapped in disposable plastics.
9. Film packets to be discarded in yellow bags.

23. BIOPSY SPECIMEN
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• Biopsy collection & transportation can also be a source of
infection.
• It should be kept in sturdy containers with securelid.
• Avoid contaminating the external surface of the container.
• Swab used for collecting micro-organisms should be
transferred slowly and carefully to the swab container.

24. • Tubes connecting hand-pieces, air/water syringe &
ultrasonic scaler unit are harbor of wide range of
micro-organisms.
• They colonize and replicate on the inner surface of
tubings.
• They serve as reservoir for micro-organisms.
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Biofilms

25. Following measures should be taken to prevent this :
A) Anti-retraction valves : (one way flow check valve). To prevent
transfer or aspiration of potentially infected material in the tubings.
B) Bacterial filter : Filters to be fitted in water lines of hand-pieces&
water syringes.
C) Chemical Disinfectants : Tubings are flushed with disinfectantslike
sodium hypochlorite.
D) Aspirators : Cleaned and flushed after every patient for 20 – 30
secs.
To be flushed with disinfectant at the end of the day.
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26.  Impression trays are sterilized as follows
metallic - autoclave
plastic – ethylene oxide
 Disinfection of alginate impressions–
Methods
- Spraying
- Immersion
Iodophors, sodium hypochlorite (1:10 concentration ) ,
phenols, formaldehyde, glutaraldehyde.
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27.  Spraying until wet or
Immersing in a 1:10
dilution of sodium
hypochlorite or an
iodophor then rinse
 Casts to be disinfected
should be fully set (i.e.
stored for at least 24
hours)
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 ADA recommends use of
 Chlorine compounds
 Iodophors
 Combination of synthetic
phenols
 Glutaraldehyde.
Dental Casts

28. • Sterilize instruments like articulators, wax knives, spatula, shade
guide, acrylic bur etc.
• Custom impression trays, base plates, occlusal rim and all other
prosthesis must be disinfected, after construction & before use in
patient.
• Articulators, casts, base plates to be disinfected by 1:10 chlorine
solution following each session or before returning to laboratory.
• Dentures washed & soaked in sodium hypochlorite for 5 mins before
delivery.
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29. ROTARY INSTRUMENTS - BURS
 Diamond and carbide burs:
After use they are placed in 0.2%
gluteraldehyde and sodium phenate (Eg.
Sporicidin) for at least 10 minutes,
cleaned with a bur brush or in an ultrasonic
bath.
Sterilize in an autoclave or dry heat
 Steel burs:
May get damaged by autoclaving. Can be
sterilized by using a chemical vapor sterilizer or
glass bead sterilizer at 2300C for 20-30 seconds.
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30. ENDODONTIC INSTRUMENTS
• Glass Bead or salt sterilizer is the best option, but they do not
sterilize the handle.
• Sterilization achieved in 10 seconds
• Dry heat is used, with instruments in closed metal or perforated
metal boxes.
• Sterilization achieved at 218oC for 15 seconds
• Gutta percha points are pre-sterilized.
• Contaminated points are sterilized by
hypochlorite.(1 min immersion).
5.25% sodium
• Then rinse with hydrogen peroxide & dry it. 30

31. • Silver cones sterilized by passing slowly over the flame for
3-4 times.
• Can also be sterilized in hot salt sterilizer.
• Files to be handled with tweezer.
• Glass slab is sterilized by swabbing the surface with
tincture of thiomersal, followed by swabbing with alcohol.
• Cement spatula is sterilized by flamming 3 or 4 times over
bunsen flame.
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32. HANDPIECE SURFACE CONTAMINATION CONTROL
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33. IMPLANTS
 Pre sterilized with Gamma radiation
 In case the implants needs to be re-sterilized conventional
sterilization techniques are not satisfactory
 Steam sterilization should not be used as it results in contamination
of surfaces with organic substances
 Dry heat sterilization also leaves organic and inorganic surface
residue
 Radio frequency glow discharge technique (RFGDT) or Plasma
cleaning is used.
 In this, material to be cleaned is bombarded by high energetic ions
formed in gas plasma in a vacuum chamber.
 Removes both organic and inorganic contaminants.
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34. Sterilization in periodontal clinic
 All diagnostic instruments are sterilized by washing in korsolex and
sterilized.
 Periodontal instruments
SHARP
e.g. knives,
scissors,
Files
Tissue holding forceps
BLUNT
Mouth mirrors,
tweezers,
artery forceps,
suture holding forceps
Periosteal elevator
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35. Sharp instruments are ideally sterilized by :
conventional hot air oven
by not sterilized:
 Boiling
 Autoclave
 2% glutaraldehyde
 Blunt instruments are sterilized by
 Autoclave
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36. Sutures
 Sutures are pre sterilized by gamma radiation
 Sutures are re- sterilized by two recommed methods are
1.Soak for a full 10 minutes completely immersed in
povidone iodine 10% solution, then rinse in sterile
saline/water.
2. Ethylene Oxide – gas sterilisation.
 Sterilising/disinfecting by other methods (autoclaving,
boiling, alcohol-soaking) are not recommended. It was
never intended to be a suture soaking solution due to its
high toxicity and the inability to ensure that allthe solution
is rinsed off before use

37. ULTRASONIC SCALERS
 Soak inserts in a container containing 70% isopropyl alcoholfor
removal of organic debris.
 Rinse cleaned inserts thoroughly in warm water to remove all
chemicals. As a final rinse, replace the insert into the scaler handpiece
and operate the scaler for 10 seconds at the maximum water flow
setting to flush out any retained chemicals
 Dry inserts completely with air syringe
 Pack in proper wrap, bags, pouches, trays, or cassettes. Add spore
tests and chemical indicators.
 Ethylene Oxide is the preferred method of choice
 Dry heat and chemical vapor methods of sterilization are considered
ineffective methods with risk of damage to materials.

38. Effect of sterilization on instruments
Sterilization Type of instrument
Stainless steel Carbon steel
Saturated steam at 250°F Amorphous substance
formed near cutting edge;
no dulling.
Dulling and oxidation of
cutting surfaces
Formalin-alcohol vapor at
270°F
Cracking of wire edge; no
dulling.
Some oxidation of
surfaces; no dulling.
Dry heat at 320°F Chipping of wire edge; no
dulling.
No visual change.
Dry heat at 340°F Chipping of wire edge; no
dulling.
No visual change
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39. Newer Disinfectants
 Surfacine : Persistent antimicrobial-drug coating that can be applied to
inanimate and animate objects containing silver .
 Ortho- phthalaldehyde : A high-level disinfectant with reduced exposure
time.
 Superoxidized water : An antimicrobial drug that can be applied to animate
and inanimate objects.

40. Thank you
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