Indian Dental Academy: will be one of the most relevant and exciting training
center with best faculty and flexible training programs for dental
professionals who wish to advance in their dental practice,Offers certified
courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry,
Prosthetic Dentistry, Periodontics and General Dentistry.
2. ContentsContents
IntroductionIntroduction
Fluid controlFluid control
Custom trayCustom tray
Impression proceduresImpression procedures
Sterilization of impressionsSterilization of impressions
ConclusionConclusion
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3. IntroductionIntroduction
IMPRESSION:IMPRESSION: (GPT 8) Impression is a(GPT 8) Impression is a
negative likeness or copy in reverse of thenegative likeness or copy in reverse of the
subject of an object, imprint of the teeth andsubject of an object, imprint of the teeth and
adjacent structures for use in dentistry.adjacent structures for use in dentistry.
REQUIREMENTS OF AN IMPRESSION:REQUIREMENTS OF AN IMPRESSION:
a. Should be an exact duplication of the prepareda. Should be an exact duplication of the prepared
toothtooth
b. Other teeth & tissue adjacent to the preparedb. Other teeth & tissue adjacent to the prepared
tooth must be accurately reproducedtooth must be accurately reproduced
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4. c. Must be free of bubbles, in the area of the finishc. Must be free of bubbles, in the area of the finish
line and occlusal surfacesline and occlusal surfaces
d. Tissue health.d. Tissue health.
e. Saliva control.e. Saliva control.
f. Gingival tissue displacement.f. Gingival tissue displacement.
g. Dimensionally stable.g. Dimensionally stable.
h. Biocompatible.h. Biocompatible.
i. The materials associated with processing,i. The materials associated with processing,
equipment and processing time cost effective.equipment and processing time cost effective.
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5. Fluid controlFluid control
Moisture will result in voids therefore salivaMoisture will result in voids therefore saliva
flow into the area must be reduced.flow into the area must be reduced.
Techniques used to create the necessary dryTechniques used to create the necessary dry
field of operation:field of operation:
a)a) Rubber damRubber dam
b)b) High volume vacuumHigh volume vacuum
c)c) Saliva ejector & cotton rollsSaliva ejector & cotton rolls
d)d) Swedopter/ specjectorSwedopter/ specjector
e)e) Moisture absorbing cardsMoisture absorbing cards
f)f) AntisialagoguesAntisialagogues
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7. Custom trayCustom tray
Improves accuracy
of an
impression material
Limiting volume
of the material
Reduces stresses
during removal
Reduces thermal
contraction
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9. FabricationFabrication
Tray extensionTray extension
- 3 to 5 mm from gingival margin- 3 to 5 mm from gingival margin
- 3 mm beyond the most distal tooth- 3 mm beyond the most distal tooth
- Outline drawn on diagnostic cast- Outline drawn on diagnostic cast
Softened modelling wax is adapted over teeth toSoftened modelling wax is adapted over teeth to
form spacer (two thickness or 2-3mm)form spacer (two thickness or 2-3mm)
Spacer is trimmed till the outline drawnSpacer is trimmed till the outline drawn
Wax is removed to form tray stops (on nonWax is removed to form tray stops (on non
centric cusps)centric cusps)
Self cure acrylic is adapted over the spacer &Self cure acrylic is adapted over the spacer &
tray is fabricatedtray is fabricated
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11. Multiple mix techniqueMultiple mix technique
Steps:Steps:
1. Verify tray fit and apply tray adhesive (for at1. Verify tray fit and apply tray adhesive (for at
least 7-15 minutes).least 7-15 minutes).
2. Select medium/ high viscosity elastomer to line2. Select medium/ high viscosity elastomer to line
the tray and low viscosity material to syringethe tray and low viscosity material to syringe
the preparation.the preparation.
3. Mix the low viscosity material to obtain a streak3. Mix the low viscosity material to obtain a streak
free mix in less than 1 min and load thefree mix in less than 1 min and load the
syringe with it.syringe with it.
4. Mix the high viscosity elastomer and load into4. Mix the high viscosity elastomer and load into
the tray without overfilling it.the tray without overfilling it.www.indiandentalacademy.comwww.indiandentalacademy.com
12. 5. Remove the retraction cord and evaluate5. Remove the retraction cord and evaluate
tissue for seepage, hemorrhage and for debris.tissue for seepage, hemorrhage and for debris.
6. Syringe the material into the prepared areas6. Syringe the material into the prepared areas
(into most distal first)(into most distal first)
7. Position the tray over the arch and seat from7. Position the tray over the arch and seat from
posterior to anterior. Continue seating in aposterior to anterior. Continue seating in a
vertical direction until the tray stops preventvertical direction until the tray stops prevent
further progress.further progress.
8. Remove the tray on setting of the material.8. Remove the tray on setting of the material.
9. Evaluate the final impression after its removal9. Evaluate the final impression after its removal
and disinfect.and disinfect.
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16. Automix techniqueAutomix technique
Gun like mechanismGun like mechanism
Uniformity inUniformity in
proportioning andproportioning and
mixingmixing
Less air incorporatedLess air incorporated
Mixing time reducedMixing time reduced
Less chance ofLess chance of
contaminationcontamination
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17. Machine mixing techniqueMachine mixing technique
An alternative method for improving impressionAn alternative method for improving impression
mixing is to use a machine mixingmixing is to use a machine mixing
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19. Handling PropertiesHandling Properties
PolysulfidePolysulfide
CondensationCondensation
SiliconeSilicone
AdditionAddition SiliconeSilicone PolyetherPolyether
WorkingWorking
Time (min)Time (min)
5 – 75 – 7 33 2 –4.52 –4.5 2.52.5
SettingSetting
TimeTime
(min)(min)
8 – 128 – 12 6 – 86 – 8 3 – 73 – 7 4.54.5
StabilityStability 1 hour1 hour Immediate pourImmediate pour 1 week1 week
1 week kept1 week kept
drydry
WettabilityWettability
andand
castabilitycastability
FairFair FairFair Fair to goodFair to good GoodGood
CostCost LowLow ModerateModerate High to very highHigh to very high Very highVery high
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20. DISINFECTION OFDISINFECTION OF
IMPRESSIONSIMPRESSIONS::
Alginate impression material:Alginate impression material:
5.25 % NaOCl immersion for 10 minutes.5.25 % NaOCl immersion for 10 minutes.
Glutaraldehyde (time inadequate)Glutaraldehyde (time inadequate)
(Spray and place in sealed plastic bag for 10(Spray and place in sealed plastic bag for 10
minutes)minutes)
Agar impression materialAgar impression material: -: -
2 % Alkaline gluteraldehyde for 10 minutes2 % Alkaline gluteraldehyde for 10 minutes
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21. Polysulfides impression material: -Polysulfides impression material: -
Immersion in gluteraldehyde, NaOCl, iodophorImmersion in gluteraldehyde, NaOCl, iodophor
phenol up to 30 minutes.phenol up to 30 minutes.
Condensation silicone materialCondensation silicone material:-:-
NaOCl, gluteraldehyde, phenol are used.NaOCl, gluteraldehyde, phenol are used.
Poly vinyl siloxane material :-Poly vinyl siloxane material :-
Excellent tolerance to immersion in NaOCl,Excellent tolerance to immersion in NaOCl,
gluteraldehyde, iodophors and phenols.gluteraldehyde, iodophors and phenols.
Polyether impression material:-Polyether impression material:-
Shorter immersion time of 10-30 minutes isShorter immersion time of 10-30 minutes is
required in NaOCl, gluteraldehyde, Iodophor andrequired in NaOCl, gluteraldehyde, Iodophor and
phenolphenol
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22. Thank you
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