IMPRESSION
Definition: It is the negative replica of the structures of the oral cavity be it hard(tooth) or soft(gingiva, mucous membrane) structures, which are used to fabricate the cast or model of the patient, and for making crowns, dentures, and other prosthesis.
CLASSIFICATION OF IMPRESSION MATERIALS.
I) Based on mode of setting & elasticity
a) Rigid
i) Reversible (thermoplastic)
- E.g. impression compound
ii) Irreversible (thermosest)
- E.g. Zoe impression paste, Impression plaster.
b) Elastic
i) Hydrocolloid
a) reversible
- E.g. Agar
b) Irreversible
- E.g. Alginate
ii) Elastomeric impression materials
- E.g. Polysulfides Polyether, Addition silicones, Condensation silicones
II) Based on type of impression & area of use
A) Dentulous
i) Primary
- E.g. alginate
ii) Secondary:
- E.g. Elastomers, Agar
B) Edentulous
i) Primary
- E.g. Impression compound, Impression plaster, Alginate
ii) Secondary
- e.g. ZOE impression paste, Elastomers for CD
III) Based on their use in dentistry
A) Edentulous- For complete denture prosthesis
- e.g. Impression compound, zoe impression paste, alginate, Elastomers
B) Dentulous
i) FPD
ii) RPD
E.g. Agar, Alginate, Elastomers
IV) Based on the amount of pressure applied
i) Mucocompressive
- e.g. Impression compound
ii) Mucostatic
- e.g. Impression plaster
V) Based on the manipulation
A) Hand mixing
i) Kneading
- e.g. Impression compound – wet kneading, putty consistency Elastomers
ii) Circular motion (with glass slab & spatula)
- eg. Zoe impression paste, polysulfide
iii) Vigorous mixing
- e.g. Alginate (figure of 8 motions)
B) Mechanical mixing
VI) Based on the tray used for impression
A) Stock tray
i) Types of tray
a) rim locked perforated
- e.g. Alginate Elastomers
b) water cooled
- e.g. Agar
c) Plastic
- e.g Orthodontic Tray
ii) Based on type of Perforation
a) Perforated
- e.g Alginate, Elastomers
b) Non Perforated
- e.g Impression Compound
B) Special Tray
i) base plate wax
- e.g. Zoe impression paste, medium body
ii) resin
should be in a chart … wud be easier to learn..
can add classification based on mode of dispensing too..
i second that :)
cud hav shown d classification in a condensed form in d beginning and later d xplained version
can u tell me the propoer way to take impression from impression compound
its awesome but we want it in chart pattern
It’s crispy…….. bt if provided n chart may undrstnd betr………..
its good
ohhhh, it is better then other, but should be in chart form……
this is sooo helpfull .. thnx :)
its sufficient…bt it wd b better when wid pictures
As all said..i also need it in a chart form..litle confusing dis..
gudd…
Very little pressure is applied in older patients while taking impression
thanks bt suppose 2b in tabular 4m 4 summary
Great… it is really usefull..
Its nice…but flow chart is usefull to understand
What’s the type of impression material that used in the top picture
Wow its really so helpful, no need to refer so many books,thank you so much
if u use a chart it would be better.
well done
I love this page