Impression material

Question 1

Indications

Answer 1

• diagnostic casts
• working casts for indirect reconstruction
• bite registration

Question 2

name this type

• impression compound
• impression plaster
• zinc oxide eugenol
• impression wax

Answer 2

non-elastic

Question 3

what are the non-elastic kinds?

Answer 3

• impression compound
• impression plaster
• zinc oxide eugenol
• impression wax

Question 4

Name the type
-Hydrocolloids
non-aqueous -elastomers

Answer 4

Elastomer impression materials

Question 5

what are hydrocolloids

Answer 5

reversible (agar)

-irreversible (alginate)

Question 6

what are non-aqueous elastomers?

Answer 6

• polysulfides
• silicon rubber
• polyethers

Question 7

what are choice and use of trays?(7)

Answer 7

• the tray should have enough spacer
  2. use perforated trays
  3. make sure the tray is clean
  4. apply only a thin layer of adhesive
  5. wait appropriate time before taking impression
  6. don’t mix adhesives and impression materials

Question 8

what advantages of manual mixing technique?

Answer 8

• low viscosity
• less viscous is easier
• silicones are easiest to mix
• followed by polyethers and polysulphides

Question 9

what 4advantages of automatic

Answer 9

• reduces mixing time
• reduces bubbles
• homogenous mix
• use correct mixing proportions

Question 10

what are the layering techniques

Answer 10

• single stage, -2 stage (double impression)

- twin mix (2 phase impression)

Question 11

Define:

• single stage
• two stage (double impression)
• twin mix (2 phase impression)

Answer 11

• one material, one setting
• first material set then another material added as a second layer
• two material layers are put together and set together

Question 12

Requirments of impression material

Answer 12

• accuracy
• dimensional stability
• tear resistance

Question 13

identify:
ability to replicate the intraoral surface details
-ability to retain its absolute dimensional size over time
-ability to resist tearing in thing sections (such as through the feather-edged material within the gingival sulcus)

Answer 13

• accuracy
• dimensional stability
• tear resistance

Question 14

what’s important to the patient?

Answer 14

• neutral taste and odor
• short setting time
• small tray
• easily removed impression
• no retakes
• non-toxic
• cost

Question 15

whats important to DENTIST

Answer 15

• EASILY MIXED
• SHORT WORKING TIMES
• GOOD QUALITY IMPRESSIONS
• LOW COST
• EASILY DISINFECTED
• SIMPLE PROCEDURE

Question 16

ability of a liquid to cover the surface of the substrate completly

Answer 16

good wettability

Question 17

Why do we want good wetting?

Answer 17

• fewer voids
• less entrapment of oral fluids by displacing water and other oral fluids from the surfaces in the mouth
• bubble-free in the impression then in dies and models
• fewer retakes
• improve adaptation of gypsum so as to prevent voids in the casts

Question 18

dimensional accuracy and stability

Answer 18

• choice and use of tray
• setting shrinkage
• permanent set
• storage stability

Question 19

one may not see 100% recovery of original dimensions in mouth

Answer 19

permanent set

Question 20

what are elastomeric impression materials

Answer 20

• polysulphides
• polyethers
• silicones

Question 21

Base paste:
-polysulphide
-filler (TiO2)
Activator paste
-lead dioxide
-sulphur
-plasticizer (dibutyl phthalate)

Answer 21

polysulfide impression material

Question 22

Base paste:
-polyether
-filler (colloidal silica)
-plasticizer
Activator paste
-aromatic sulphonate
-filler
-plasticizer (dibutyl phthalate)

Answer 22

polyether impression material

Question 23

Base paste
-silicone polymer
-filler(colloidal silica)
-organo-tin compound
Activator paste
-silicone polymer
-filler(colloidal silica)
-Tetra-ethyl silicate

Answer 23

silicone impression material

Question 24

poor dimensional stability due to evaporation of alcohol(must be poured immediately after removal from mouth)

Answer 24

silicone impression material (condensation cured)

Question 25

Base paste
-Silicon polymer
-filler (colloidal silica)
-silanol
Activator paste
-silicone polymer
-filler (colloidal silica)
-platinum catalyst

Answer 25

silicone impression material (addition cured)

Question 26

• cholorplatinic acid
• thought to be source of H gas release, if contaminate w/ water
• solved by the addition of palladium compounds to absorb H2
• retarded if contact w/: latex gloves, sulfur rubber stabilizers present in rubber gloves

Answer 26

platinum salt catalyst

Question 27

disinfection of impressions

Answer 27

• chlorine solutions
• aldehyde solns
• others (iodine soln, phenols)
• Addition reaction silicones
• Condensation reaction silicones
• polyethers

Question 28

bad impressions

Answer 28

• extra chair-side time
• repeat visits for the px
• px distress
• waste of expensive materials
• remake bill from the lab
• spoild relationsip with lab

Question 29

poor reproductions of surface detail

Answer 29

POOR REPRODUCTION OF SURFACE DETAIL
-rough or uneven surface
-air bubbles 
-irregular shaped voids
POOR FIT
-distortion
-casting too big
-casting too small

Question 30

what are dithiocarbamates?

Answer 30

chemical components which cause the inhibition of the setting of vinyl polysiloxane putty

Question 31

is used to obtain cast on w/c a planned resorations is fabricated

Answer 31

an impression or negative likeness of teeth and surrounding structures

Question 32

is an EXACT negative replica of each prepped tooth and must include all prep’d surfaces as well as an adequate amt of unprep’d tooth structure adjacent to the margins.

Answer 32

summary

-good impression

Question 33

what makes to successful impressions?

Answer 33

health of soft tissues and control of salivaryflow