STERILIZATION IS DEFINED AS A PROCESS BY WHICH AN ARTICLE, SURFACE OR MEDIUM IS FREED FROM ALL MICRO-ORGANISMS EITHER IN THE VEGETATIVE OR SPORE STATE. DISINFECTION RFERS TO A PROCESS THAT DESTROYS OR REMOVES MOST IF NOT ALL PATHOGENIC ORGANISM BUT CERTAINLY NOT BACTERIAL SPORES.

1. STERILIZATION &
DISINFECTION IN
PROSTHODONTICS
UNDERTHE ABLE GUIDANCE OF:-
DR.(PROF)JAYANTA BHATTACHARYA
[HOD&PRINCIPAL]
DR.(PROF)SAMIRAN DAS
DR.(PROF)PREETIGOEL
DR.SAYANMAJUMDAR
DR.SUBHABRATAROY
PRESENTED BY:-
BAISHALI GHOSH
1STYEAR PGT
DEPARTMENT OF
PROSTHODONTICS, CROWN &
BRIDGE

2. CONTENTS
 TERMINOLOGIES
 FACTORS INFLUENCING EFFICACY OF STERILANT/
DISINFECTANT
 PHYSICALAGENTS OF STERILIZATION
 CHEMICALAGENTSOF STERILIZATION
 SPAUDLING’SCLASSIFICATION
 LEVELOF DISINFECTION
 PROSTHODONTIC IMPLICATIONS

3. TERMINOLOGY
STERILIZATION
 STERILIZATION IS DEFINED
AS A PROCESS BYWHICH AN
ARTICLE, SURFACEOR
MEDIUM IS FREED FROM
ALL MICRO-ORGANISMS
EITHER INTHEVEGETATIVE
OR SPORE STATE.
DISINFECTION
 DISINFECTION RFERSTO A
PROCESSTHAT DESTROYS
OR REMOVES MOST IF
NOT ALL PATHOGENIC
ORGANISM BUT
CERTAINLY NOT
BACTERIAL SPORES.
It results in reduction of atleast
106
colony forming micro −
organisms and their spores.
It results in reduction of atleast
103
colony forming micro −
organisms but not spores.

4. TERMINOLOGIES
ASEPSIS It is a process where chemical
agents(antiseptics) are applied on
the body surfaces(skin) , which kill
or inhibit micro-organisms present
on the skin.
SANITIZATION It refers to the reduction of
pathogenic microbial
population to a level at which
items are considered to be
safe to be handled without
protective attires.

5. FACTORS
INFLUENCING
EFFICACYOF
STERILANT/
DISINFECTANT
MICOBIAL LOAD
NATURE OF ORGANISMS
CONCENTRATION
NATURE OF STERILANT/DISINFECTANT
DURATION OF EXPOSURE
TEMPERATURE
LOCAL ENVIRONMENT

6. PHYSICAL
AGENTSOF
STERILIZATION
DRYING
HEAT
DRY HEAT
FLAMING
INCINERATION
HOT AIR OVEN
MOIST HEAT
TEMPERATURE<100˚
PASTEURIZATION
WATER BATH
INSPISSSATION
TEMPERATUREAT
100˚
BOILING
TYNDALIZATION
TEMPERATURE
>100˚
AUTOCLAVE
FILTRATION
DEPTH FILTERS
MEMBRANE FILTERS
RADIATION
IONIZING
RADIATION
NON-IONIZING
RADIATION

7. DRY HEAT
• METHODS:-
• Longer time exposure in flame till
they become red hot=
• Shorter time exposure
without allowing items to become hot=
FLAMING
• Temperature=870-1200˚c
• Indication:-To dispose anatomical & microbial waste
INCINERATION
HOT AIR OVEN
MECHANISMOF ACTION:-
a)Denaturation of bacterial
protein.
b) Oxidative damage
c) Elevated levels of
electrolyte
MATERIALS STERILIZED:-
Inoculating wires
tips of forceps
Fragile materials like
mouth of test tube

8. HOTAIR
OVEN
Holding
temperature=160˚C
Time=2 hours
TEMPERATURE:-
MATERIALS
STERILIZED
GLASSWARES:-
Petri dish
Flask
Test tube
SURGICAL
INSTRUMENTS:-
Scalpel
Forcep
CHEMICALS:-
Paraffin
Fats
Oil

9. PHYSICAL
AGENT
CHEMICAL
INDICATOR
BIOLOGICAL
INDICATOR
• Temperature control
byTHERMOCOUPLES
• BROWNE’STUBE
• Green spot is observed after
60 mins at 160˚C indicating
complete sterilization
• BACILLUS ATROPHAEUS
• Spores 106
of B.atrophaeus are used to
check the effectiveness of
sterilization by dry heat.

10. MOIST HEAT
TEMPERATURE
<100˚C
PASTEUERIZATION
HOLDER
METHOD
63˚C for 30 minutes
Kills all non sporing pathogens
except Coxiella burnetii which is
heat resistance
FLASH
METHOD
72˚C for 20 seconds followed by
rapid cooling to 13˚ or lower
WATER BATH
Disinfection of
serum, body fluids
& vaccines
BACTERIAL
VACCINES are
disinfected at 60˚C
for 1 hour
SERUM can be
disinfected at 56˚C
for 1 hour
INSPISSATION
Article heated on 3
successive days at
80-85˚C by inspissator
1st exposure kills vegetative
forms
In the interval remaining spores
germinate into vegetative forms & are
then killed
Used to sterilize
Egg based media like
Lowenstein-Jensen medium
Serum based media like
Loeffler’s serum slope
MECHANISM OF ACTION:-
Denaturation & coagulation
of protein

11. TEMPERATURE AT
100˚C
BOILING
Boiling in water for 15 minutes kills vegetative forms but not spores
Not suitable for sterilization of surgical instruments
STEAMING Koch’s or Arnold’s
steam sterilizer
Exposed to steam(100˚C) at
atmospheric pressure for 90
minute
Sterilize media which are
decomposed at high
temperature of autoclave
TYNDALLIZATION
Steaming at 100˚C for 20 minutes for 3 consecutive
days
Used to sterilize gelatin or egg product

12. AUTOCLAVE
VAPOUR PRESSURE= SURROUNDING PRESSURE
WATER STARTS BOILING
AT NORMAL PRESSURE; WATER STARTS BOILINGAT 100˚C
WHEN PRESSURE INSIDE A CLOSED VESSEL INCREASES
TEMPERATUREAT WHICHWATER BOILSALSO INCREASES
STEAMABOVE 100 ˚C HAS BETTER KILLING PROPERTY THAN DRY HEAT

13. HEATING PERIOD HOLDING PERIOD
Holding period then
begins.
COOLING PERIOD
Whentheholdingperiod isover,
theheateristurnedoffandthe
autoclaveis allowedto cooltill
thepressurereaches
atmosphericpressure.The
dischargetap isopenedslowly
andair isletinto theautoclave
121˚C for 15minutes atapressureof 15psi
126˚C for10minutes at apressureof 20 psi
133˚C for 3 minutes atapressureof 30psi
Sufficientwater isadded to
thecylinder, and thematerial
to besterilized isplaced on
thetray.
Thelid isscrewedtight with
thedischarge tapopen, and
theautoclave isheated.
Thesteam-airmixtureisallowedtoescape
freelvtillalltheairhasbeendisplaced.
TEST:-
-Thiscanbetestedbyleadingtheescaping
steamintoapailofwaterthroughrubber
tubing.Whennomoreairbubblescomeoutin
thepail,thedischargetap·isclosed.
Thesteam pressurerise~
insideand,then itreaches
thedesired set level,the
safety valve opens and the
excesssteam escapes

14. TYPES
OF
AUTOCLAVE
 It displaces the ambient air and forces it out of exhaust valves so
that the remaining steam can sterilize the contents.
Most commonly used autoclave
DISADVANTAGE:- INEFFICIENTAIR DISCHARGE
It is more suited where air cannot be easily removed from
sterilization media
The vacuum function in these autoclaves allows deeper
sterilization of the contents
 It completely evacuates the ambient air within, with a high quality
pulsating vacuum pump that removes air pre-sterilization and post
sterilization, allowing high-temperature steam to penetrate and
sterilize hard-to-reach areas within.

15. CLASSIFICATION NATURE OFTHE
AUTOCLAVE
SUITABLE FOR
NTYPE DOWNWARD
DISPLACEMENT
Unwrapped solid.
Instruments to be used
immediately.
If wrapped pouches will get
sterilized instead of
instruments.
STYPE VACCUM Instruments wrapped in
sealed pouches.
BTYPE VACCUM Both wrapped and
unwrapped instruments.
Provide better penetration
and sterilization of wrapped
hollow/porous instruments.

16. FILTERS
They are porous filters that retain
all particles throughout the
depth of filter, rather than just
one surface.
They are porous filters that retain
all particles on one surface that
are larger than their porous size.
MECHANISM
COMPOSITION Mats of metallic , polymeric or
inorganic materials like:-
Diatomaceous earth
Unglazed porcelain
Asbestos filter
Sintered glass
Cellulose acetate
Cellulose nitrate
Polycarbonate
Polyvinylidene fluoride
USED FOR Filtration of high particle
loaded fluid specially for
industrial purposes such as
filtration of beverages.
Pore
diameter
Filters
0.22µ Most bacterias
0.45µ Colliform bacteria from
water
0.8µ Airborne microbes from air

17. RADIATION
COLD
STERILIZATION
• Breakage of DNA without rise
in temperature
EXAMPLES
• GAMMA RAYS
• X-RAYS
• COSMIC RAYS
USES
• Disposable plastic supplies
such as plastic syringes ,
catheter
• Sutures, Grafts
EXAMPLES
• ULTRAVIOLET
RADIATIONS
• INFRARED RADIATIONS
USES • Disinfection of operation
theaters

18. PLASMA
STERILIZER
• It refers to a gaseous state consisting of ions, photons&
free electrons & neutral uncharged particles ( such as O &
OH)
PLASMA
• It is a special device used to create plasma state.
• They maintain uniform vaccum inside chamber.
PLASMA
STERILIZER
• H2O2 alone or a mixture of H2O2 & peracetic acid are
used to produce O & OH which are effective in killing
microbes & spores.
CHEMICAL
STERILANT
• Low temperature of 37-44c throughout the process which
preserves the integrity of heat labile items.
PROCEDURE
• For materials that cant tolerate high temperatures like:-
Arthroscope Urethroscopes etc.
USES
RECENT ADVANCES:-

19. INDICATORS
FOR
MONITORING
STERILIZATION
Displays the parameters of sterilization cycle
GEOBACILLUS STAEROTHERMOPHILLUS
 Autoclave
Plasma Sterilizer
BACILLUS ATROPHAEUS
Dry heat
TYPE NAME USED
I EXPOSURE INDICATOR
or EXTERNAL PACK
CONTROL
Used on external surface of each pack to indicate
that the pack is sterilized.
II BOWIE-DICKTEST Checks air leaks & steam penetration to ensure
proper functioning of autoclave
III SINGLE PARAMETER
INDICATOR
Obsolete now
IV INTERNAL PACK
CONTROL
Checks 2 of the critical parameters:- time, steam
quality & temperature
V INTERNAL PACK
CONTROL
Checks all 3 critical parameters
VI EMULATING INDICATOR It is cycle specific, the stated values corresponds to
the critical variables that the sterilizer manufacturer
has defined for that cycle of sterilization.

20. CHEMICALAGENTSOF
STERILIZATION

21. ETHYL ALCOHOL
ISOPROPYL ALCOHOL
used in hand rubs as antiseptics.
Act by denaturing protein &
possibly by dissolving
membrane lipids.
FORMALDEHYDE
GLUTARALDEHYDE
Fumigation of closed areas like
operation theater
 ClinicalThermometer & small
instruments are disinfected by
soaking in isopropyl alcohol for 10-15
minutes.
Sterilize equipments like
ENDOSCOPE.
2% concentration=CIDEX
Takes 20 minutes to sterilize
They combine with nucleic acids,
proteins & inactivate them.

22. HALOGEN MECHANISM PREPARATION USE DISADV
ANTAGE
IODINE Oxidizing cell
constituents
TINCTURE OF IODINE
(Preparation of Iodine(2%) in
ethanol solution of potassium
iodide)
IODOPHORE
(Prepared by complexing
Iodine with an organic carrier
such as povidone)
Effective antiseptic
Preoperative
disinfectant &
antiseptics in
Laboratories.
Causes Skin allergies &
yellowish skin
discoloration.
CHLORINE All preparations yield
Hypochlorous acid
(HClO), which causes
oxidation of cellular
material & destruction of
vegetative bacteria &
fungi but not spores.
SODIUM HYPOCHLORITE
(Household Bleach)
CALCIUM HYPOCHLORITE
 Disinfection of
municipal water
supplies.
Disinfecting blood
spillage area
Remove stain from
clothes
Organic matter
interferes with its
action
CARCINOGENIC
Corrosive
Explodes on
exposure to sunlight.

23. ETHYLENE
OXIDE
FORMALDEHYDE
GAS
It is especially used for sterilizing heat-sensitive equipment like
heart-lung machines, respirators, suture materials, dental
equipments.
This is employed for fumigation of operation theatres and
other rooms.
CATIONIC SURFECTANTS Examples:-
QUATERNARYAMMONIUM COMPOUNDS
(Benzalkonium Chloride)
Mechanism:-
Disrupt microbial
membrane Use:-
Disinfect food utensils,
small instruments
Skin antiseptics
ANIONIC SURFECTANTS
Strong detergent but weak antimicrobial properties.
eg- Common soap
AMPHOTERIC SURFECTANTS
 Antimicrobial property of cationic surfactant as well as
detergent property of anionic surfactant.
Eg-Tego compounds(DDAG- Dodecyl di aminoethyl glycine)

24. PHENOLIC
COMPOUND
MECHANISM OF ACTION:-
They act by denaturing protein & disrupting cell membrane.
CRESOLS
Most commonly used for sterilization of:-
a)Infecting glass wares
b)Cleaning floors.
c)Disinfection of excreta.
It is active against wide range of organism
They are not inactivated by organic matter.
CHLOROXYLENOL It is an active ingredient of Dettol.
It is less toxic & irritant.
HEXACHLOROPHENE
More active against Gram positive compared
to Gram negative.
It is applied on skin as prophylactic measure
against Staphylococcal infection

25. BIGUANIDES
[CHLORHEXIDINE
GLUCONATE]
EFFECT ON MICROBES
• BACTERIOCIDAL
• SPOROSTATIC
• MYCOBACTERIOSTATIC
• 4% CHG is effective against Clostridium difficile spores
PROPERTIES
• Broad spectrum efficacy
• Substantivity for skin
• Longer action than alcohol

26. SPAUDLING’S
CLASSIFICATION
CRITICAL
INSTRUMENTS
SEMI-CRITICAL
INSTRUMENTS
NON-CRITICAL
INSTRUMENTS
Items are those which
enter sterile tissue or the
vascular system and pose a
high risk of infection if the
article is contaminated.
Articles which come
in contact with
mucous membranes
or non-intact skin
These items come in
contact with intact skin
but not mucous
membranes.
Heat-stable
AUTOCLAVE
Heat-sensitive
Ethylene oxide
Hydrogen peroxide
Gas plasma.
Glutaraldehyde is the
most commonly used
high-level disinfectant.
They can be cleaned
or treated with low-
level disinfectants

27. LEVELOF
DISINFECTION
LEVEL OF DISINFECTION KILLS EXAMPLE
HIGH Kills all microbial
pathogens and might have
some activity against a
smaller number of spores
if the contact time is
increased.
Glutaraldehyde
Hydrogen peroxide.
INTERMEDIATE Kills all microbial
pathogens including
mycobacteria and non
enveloped viruses except
spores.
Alcohol
Iodophor
LOW Kills only vegetative
bacteria, fungi and lipid-
enveloped viruses.
Quaternary ammonium
compounds

28. PROSTHODONTIC
IMPLICATIONS

29. INFECTION
CONTROL IN
PROSTHODONTICS
PATIENT
SCREENING
PERSONAL
HYGIENE &
PROTECTION
INSTRUMENT
PROCESSING
SURFACE
ASEPSIS
PATIENT
TREATMENT
LABORATORY
DISINFECTION
STEPS:-

30. CROSS
INFECTION
The transmission of a communicable
disease, most commonly caused by
an infectious micro-organism,
either directly from one person to
another by direct contact, or
indirectly by contaminated
instruments, equipments, surfaces,
water, and air..

31. PERSONAL
PROTECTIVE
EQUIPMENT
GLOVES
STERILE SURGEON’S GLOVE
Use during invasive procedures, which include surgery.
They are the most expensive type of gloves because of their
sterility and the high degree of quality control used during
their manufacture.
NONSTERILE EXAM GLOVES
It may be worn for examination and nonsurgical
procedures that are not invasive and when
handling most contaminated objects.
They are not subjected to same quality control
standards as sterile surgeon’s gloves.
OVER GLOVES
They are thin plastic “food handler” gloves
that may be worn over nonsterile exam gloves
when it is necessary to touch objects not in the
oral cavity, such as patient charts, during patient
treatment.
UTILITY GLOVES
They are heavy, nonsterile, puncture-resistant gloves that
should be worn during cleaning and processing of contaminated
instruments, cleaning and disinfecting of contaminated surfaces,
and handling of chemicals.

32. David A. Christopherson et al , High-Efficiency Particulate Air Filters in the Era of COVID-19: Function
and Efficacy, Otolaryngology– Head and Neck Surgery 2020, Vol. 163(6) 1153–1155
HEPA filtersare usually manufactured by
microfiberglassmade withmultiple layers
of randomly arranged fibers,withdiameters
ranging from 2to 500nm.
Asair flows through thefilterand inbetweenthe fibers,
airborne particles—suchasrespiratory and aerosol
droplets—will betrapped by1of 3mechanisms.
A)Particle sizes>.1µm=impaction and interception are
themost significant.
B)Particle sizes<.1µm=Diffusion isthe dominant
mechanism fortrapping
C)Particle sizes0.1and 1 µm= all mechanisms capture
theparticles to some degree.
Adhesionto filterfibersmayoccurthrough:-
i) VanderWaalsforces
ii) electrostaticattraction
iii) capillaryaction.
INERTIALIMPACTION:-
Largeparticlesarecapturedbythis mechanism.
Dueto theirsize,theseparticlescannotadjust to suddenchangesinairflowaround fibre&runstraight
intofibre&getembeddedinto thefibre.
INTERCEPTION:-
Mediumparticlesarecaptured bythismechanism.
Particlesfollowalineofflowintheairstreamcomewithin 0.1µm radius ofthefibre&adhereto it.
DIFFUSION:-
Verysmallparticlesarecapturedbythismechanism.
Thesmallparticlesarebounced,blownorcollidedwithfibre&aredelayed
Thisissimilarto BROWNIANMOVEMENT.

33. AEROSOLS
PRECAUTIONSTHAT
SHOULD BETAKEN DURING
COVID 19 OUTBREAK:-
Preoperative mouth rinse with
suitable mouthwash help reduce
infectious load.
Using air
purification
systems
HEPA filters
Use of
personal
barrier
protection
Use of high
velocity air
evacuation.

34. FACE MASK
The majority of aerosols that may be produced by human cough <1
µm .
SARS-CoV-2 virion is reported to be 0.06-0.14 µm.
CDC has recommended the use of HEPA filters in powered air purifying
respirators as well as masks for effective filtration of SARS-COV2
HEPA filters have at least 99.97% efficiency for removing all particles,
with even higher efficiencies for particles both larger and smaller than
0.15 µm.
HEPA FILTER MASKS
André Ulisses Dantas BATISTA, Prosthodontic practice during the COVID-19
pandemic: prevention and implications, Braz. Oral Res. 2021;35:e049
Factors that determine
the efficiency of masks:-
i)Number of layers
ii)The shape of the mask
iii)Facial fit
iv)Breathing ability of the
material used
v)Filtration efficiency
N-95 MASKS
The N95 mask prevents the
inhalation of 0.3 µm particles by
95%
It is 5 layered.
SURGICAL MASK
surgical masks filter particles ≥ 5 µm from the air.
It is 3 layered .

35. Protective eyewear with side shields must be worn by the dental care provider
during any patient treatment or procedure.
This is not only for protection against infectious disease agents but also for
protection against objects and chemicals that could damage the eyes.
CURING LIGHTS=UV light can cause cataracts and retinal damage.
PROTECTIVE
EYEWEAR
PPE

36. STERILIZATION
OF
COMMONLY
USED
INSTRUMENT
• Dry heat
• Ethylene oxide
Mouth mirror
• Dry heat
• Ethylene oxide
Carbon steel
hand instrument
• Dry & moist heat
• Ethylene oxide
Stainless steel
instruments
Tissue retractors

37. STERILIZATION
OF HANDPIECE
After the end of dental procedure, the
handpiece must be operated for 5-10
seconds over the wash basin while ejecting
air & water
Then, after being detached from tubing &
connections with the unit, it must be
meticulously washed & brushed under
running water
After being Dried with an absorbent paper
,handpiece reconnected to tubing & operated
for 3-5 seconds only with air so that water
residues removed from the tubing.
Handpiece is lubricated with lubricant & operated
again for 10-20 seconds only with air so that
lubricant is properly distributed throughout the
sensitive areas of head of handpiece
Handpiece then enclosed in pouch & placed
in autoclave

38. STERILIZATION
OF BURS
Meticulous cleaning done,to
remove tooth debris, residues
of dental material, blood clots
.
Placed in ultrasonic baths at a
temperature of 60c , burs
vibrate at a frequency of 60-80
kHz for at least 15 minutes.
Burs are then dried off with
absorbent paper.
PRECAUTIONS WHILE STERILIZING
BURS:-
a) Carbon steel bur cant be placed in
autoclave because they will undergo
oxidation.
b) Dry heat oven, chemical favour may
be used for sterilization of burs but
they reduce the cutting efficiency of
burs

39. DISINFECTION
OF
IMPRESSION
ADARECCOMENDATIONS
PreferredinELASTOMERSbecauseof:-
a)Greaterantiseptic efficacy
b)Compensateforthepolymerization
shrinkageofthesematerials,improving
accuracy.
Preferreddisinfectionmethodfor
HYDROPHILICMATERIALS
:ituseslessdisinfectantsolution and
it canreducethepossibility of
distortion afterprolongedimmersion.

40. Debarchita Sarangi et al, Infection Control in Prosthodontics: A Review, Indian Journal of Forensic Medicine & Toxicology, October-December 2020, Vol. 14, No. 4
•Immersed in 2% IODOPHORE solution for
20 minutes.
IMPRESSION COMPOUND
•Immersed in 2% GLUTARALDEHYDE
solution for 10 minutes.
ZINC OXIDE EUGENOL
•SODIUM HYPOCHLORITE spray-rinse-spray
Kept under damp gauze or in a sealed pack for
less than 10 minutes.
ALGINATE
•SODIUM HYPOCHLORITE spray-rinse-spray
Kept under damp gauze or in a sealed pack for 10
minutes.
AGAR
•Immersed in 2%GLUTARALDEHYDE at room
temperature for less than 10 minutes.
Rinsed with sterile water for 45 seconds & then dried.
POLYETHER
•Immersed in 2%GLUTARALDEHYDE solution for 10 minutes .
POLYSULFIDE
•Immersed in 2% GLUTARALDEHYDE for 10 minutes.
ADDITION SILICON
•Immersed in 2% GLUTARALDEHYDE for 10 minutes.
CONDENSATION SILICON
•Phenolic spray can also be used.
•Not compatible with chlorine.
•Phenolic spray can be used.
•Short-term glutaraldehyde has
shown to be effective but time is
inadequate
•Do not immerse in disinfectants
•Short term exposure only to avoid
distortion.

41. GIANNIA ET ALL,Disinfection of dental impression materials and its effects on
dimensional changes, Revista Odontológica Mexicana 2021; 25 (2): 154-159
WETTABILITY:-
POLYETHER >VINYLPOLYSILOXANE
Wettability of the impression materials improves after10minutes
Improvements inwettability of 0.5% GLUTARALDEHYDE disinfected impression material surfaceswereobserved asmeasurement time
increased
There aresignificantdimensional changes inPOLYVINYLSILOXANE SAMPLES
disinfectedfor20minutes with
2%GLUTARALDEHYDE
1%SODIUM HYPOCHLORITE
Theyevaluated the dimensional precision inimpressions of :-
ALGINATE
ZINC OXIDE EUGENOL PASTE
disinfected with :-
1%SODIUM HYPOCHLORITE
2%GLUTARALDEHYDE.
AlZainetal
Nimonkaretal
Ismailetal
2017
2019
2019
ZOE paste impressions disinfected with 1%sodium hypochlorite and 2%glutaraldehyde for 10 or 60minutes
did not affectdimensional stability,
Alginate impressions theimmersion should only be10minutes so asnot to affectthe dimensional accuracy
Greaterdiscrepancy
INFERENCE
GLUTARALDEHYDE ISTHE GOLD STANDARD FOR DISINFECTIONOF IMPRESSION MATERIALS BECAUSE OF ITS
PROPERTIESOF:-
A) MINIMAL DIMENSIONAL DISTORTION
B) IMPROVEDWETTABILITY

42. SCOPE FOR
ADVANCEMENT
Among the other disinfection alternatives, Azevedo
et al. pointed out that there is high antimicrobial efficiency without significant changes
in the 3D shape of the addition silicone impressions, using hydrogen peroxide at 3%
Furthermore, hydrogen peroxide is the least explored disinfectant and could be a
worth alternative for disinfecting silicone impressions
HYDROGEN PEROXIDE
AUTOCLAVE
There are dimensional changes within the recommended ranges for addition
silicone impressions after autoclaving.
Therefore, this impression material may be acceptable clinically for fabricating
fixed dental prostheses (FPD).
-Asopa et al., 2020
GIANNIA ET ALL,Disinfection of dental impression materials and its effects on dimensional changes, Revista Odontológica Mexicana 2021; 25 (2): 154-159

43. DISINFECTION
OF DENTAL
CASTS
Saso Ivanovski, Disinfection of dental stone casts:
Antimicrobial effects and physical property alterations
REVIEW OF STUDIES ON DISINFECTIONOF DENTAL CASTS
1995 Saso Ivanowski et al
DISINFECTION OF DENTAL STONE CASTS: ANTIMICROBIAL
EFFECTS AND PHYSICAL PROPERTY ALTERATIONS.
PROBLEM NOTED:- Microorganisms which have contaminated the surface of an impression can be recovered
readily fromgypsum casts at 1 hand 24hperiods following the pouring-up of the impression.
This indicates clearly that GYPSUM CASTS are possible routes of transmission for first 24
hours. Importantly thisis the timeduring whichcasts are most likely to be handled.
RESULT :- Theincorporation of some of thedisinfectants into thestone mixproduced asignificantand acceptable
reduction inthenumber of viablebacteria present1hand 24haftercontamination but might also alter
physical dimension.
Disinfectants that were able to
achieve satisfactory levels of
disinfection at 1 hr & 24 hr.
GLUTARALDEHYDE Least effect on physical properties of
cast.
POVIDONE IODINE
DETAIL REPRODUCTION & SETTING
EXPANSION= unaltered.
SETTINGTIME & COMPRESSIVE
STRENGTH = altered
Disinfectants that didn’t achieve
satisfactory disinfection after 1 hr &
24 hr
CHLORHEXIDINEGLUCONATE
DecreasedCOMPRESSIVE STRENGTH by 40%
Doubles the SETTINGTIME
SODIUM HYPOCHLORITE
Increases SETTINGTIME.
COMPRESSIVE STRENGTH= falls much below
ADA specifications.

44. K Meghashri et al EVALUATION & COMPARISON OF HIGH LEVEL MICROWAVE OVEN DISINFECTION WITH CHEMICAL DISINFECTION OF DENTAL GYPSUM CAST
Journal of International Oral Health 2014; 6(3):56-60
2014
K Meghashri
et al
EVALUATION & COMPARISONOF HIGH LEVEL MICROWAVE OVEN DISINFECTIONWITH
CHEMICAL DISINFECTIONOF DENTALGYPSUMCAST
MECHANISM OF
MICROWAVE OVEN
DISINFECTION
MICROWAVES= Electromagnetic waves produced by a generator
called Magnetron
Microwave causes POLAR molecules to oscillate
Molecular vibration causese increased temperature
Micro-organisms are polar molecules, when excited at high
frequency it causes disaggregation of their molecular structures.
REPORT 5min of microwave oven irradiation
in an ordinary household
microwave oven set at 900Watt.
0.5% NaOCl, at pH adjusted to 10, 10 min
immersion
VS
Microwave oven irradiation showed efficacy greater than chemical disinfectant with
least dimensional deformity.

45. STERILIZATION
&DISINFECTION
OF IMPRESSION
TRAY
• Heat sterilize by
AUTOCLAVE
• ETHYLENE OXIDE
sterilization
ALUMINIUM
OR CHROME-
PLATED
IMPRESSION
TRAY
• Iodophore or Sodium
hypochlorite
• Discarded after use
CUSTOM
TRAY

47. DISINFECTION
OFCOMPLETE
DENTURE
Masoomeh Aslanimehr, In vitro comparison of the effects of microwave irradiation and chemical and mechanical methods on the disinfection of complete dentures contaminated with Candida albicans, ©
2018 Dental Research Journal | Published by Wolters Kluwer - Medknow
Dentures
immersed in
150ml distil water
for 15 minutes
Corega tablet
dissolved in
water.
Sodium carbonate peroxide works by oxygen-
liberating process as active ingredient H2O2
is oxidized to release oxygen which is
observed as effervescence & aids in cleansing.
COREGA(Alkaline Peroxide)
2% GLUTARALDEHYDE
The dentures placed for 10 min in sterile containers containing 2%
glutaraldehyde,
BRUSHING
The dentures were brushed for 5 min in sterile distilled water.
MICROWAVE IRRADIATION
Dentures placed in sterile
glass containers containing
150 ml of distilled water.
Containers placed in centre
of microwave oven
Exposed to 650 watt for 3
minutes.
CHLORHEXIDINE
For denture disinfection, 2% CHX was the most effective concentration. Chlorhexidine is effective in disinfection of
dentures contaminated with azole-resistant C. albicans.

48. MICROWAVE IRRADIATION
2% GLUTARALDEHYDE
Most effective in reduction of microbial
load( mainly fungal load) from the
complete denture.
DNA remaining in dead microorganisms can turn
into living microorganisms, it can cause infection to
recur.
Hence proper examination of microwave
irradiated dentures and mechanical cleansing
essential for proper disinfection of dentures.
COREGA(Alkaline Peroxide) Corega tablets decreased the colony count,
but they did not fully disinfect the dentures.
The manufacturer claims this tablet has
antibacterial effect but not antifungal effect.

49. PROTOCOLS OF DENTURE DISINFECTION DURING COVID 19
When elderly denture
wearers are infected
with covid 19, they
should immediately
discard acrylic dentures.
CAUSE- Acrylic dentures
are the harbour for
Staphylococcal species
Disinfection of dentures
should be done
immediately when it is
removed from mouth
before saliva dries off
Tray size should be
accurate to prevent
coughing effect during
impression taking.

50. DISINFECTION
OFCOBALT-
CHROMEALLOY
REMOVABLE
PARTIAL
DENTURE
DISINFECTANTS
CHLORHEXIDINE
DIGLUCONATE
HAEMATOPORPHYRIN
DERIVATIVE
(PHOTOGEM-Haematoporphyrin
dichloride with mixture of sulphuric
acid & acetic acid)
ACTIVE AGAINST
Staphylococcus aureus
Streptococcus mutans
Candida albicans

51. SURFACE
ASEPSIS
There are two general approaches for surface
asepsis :-
a) Clean and disinfect contaminated surface
b) Prevent surface from becoming
contaminated by use of surface covers
According to Miller and Palenik in 1994
chemicals used for surface and equipment
asepsis are –
CHLORINE e.g. sodium hypochlorite
PHENOLIC COMPOUNDS :—
(a) WATER BASED –
Ortho- phenyl phenol
Tertiary amyl phenol
O benzylp-chlorophenol
(b) ALCOHOL BASED –
Ethyl or iso propyl alocohol with O phenyl
phenol or tertiary amylphenol
(c) IODOPHOR – butoxy poly propoxy poly
ethoxy ethanol iodine complex.
ORTHO-PHENYL PHENOL
TERTIARYAMYL PHENOL
O BENZYLP-CHLOROPHENOL

52. PATIENT
TREATMENT
The working area is sprayed and left for 10 mins before any procedure starts
along with the wiping of the operatory and chair with a disinfectant solution.
The chair is covered with a disposable plastic sheath which has to be removed
subsequent to the treatment.
 All the patients are advised to rinse with chlorhexidine gluconate 0.12% and wear
protective eye wear before the commencement of the treatment.
 The operator should wash the hands with antimicrobial cleanser before gloving
and should only touch the patient and the disinfected area once gloved.
UNIT DOSE CONCEPT Introduced to reduce cross contamination.
Refers to dispensing off a certain amount of
substance required to accomplish a certain
procedure, prior to patient contact.
Disposing excess material after the procedure is
performed.

53. LABORATORY
DISINFECTION
All prosthesis entering the laboratory are
disinfected by immersing in 5.25% SODIUM
HYPOCHLORITE for 10 minutes
Laboratory countertops are cleaned with
disinfectants.
Laboratory burs are sterilized and are used for
one patient only
While polishing with lathe, OCTENIDE added
to pumice to reduce the micro-organism by
99.999%.
Before returning the prosthesis to clinic , they
are sterilized & packed in air tight packages.

54. CONCLUSION

55. REFERENCE
David A. Christopherson et al , High-Efficiency Particulate Air Filters in the Era of
COVID-19: Function and Efficacy, Otolaryngology– Head and Neck Surgery 2020,
Vol. 163(6) 1153–1155
André Ulisses Dantas BATISTA, Prosthodontic practice during the COVID-19
pandemic: prevention and implications, Braz. Oral Res. 2021;35:e049
Saso Ivanovski, Disinfection of dental stone casts: Antimicrobial effects and
physical property alterations Dental Materials/January 1995
K Meghashri et al EVALUATION & COMPARISONOF HIGH LEVEL MICROWAVE
OVEN DISINFECTIONWITH CHEMICAL DISINFECTIONOF DENTAL GYPSUM
CAST
Journal of International Oral Health 2014; 6(3):56-60
Masoomeh Aslanimehr, In vitro comparison of the effects of microwave
irradiation and chemical and mechanical methods on the disinfection of
complete dentures contaminated with Candida albicans, © 2018 Dental Research
Journal | Published by Wolters Kluwer - Medknow