Impression trays and impression techniques

Question 1

which impression is used for construction of special tray ?

Answer 1

primary impression

Question 2

what type of materials are used for primary impression ?

Answer 2

impression compound or alginate (flexible)

Question 3

what types of materials are used for secondary impression ?

Answer 3

zinc oxide eugenol (rigid) or rubber base (flexible)

Question 4

pouring material of primary impression :

Answer 4

plaster of paris

Question 5

pouring material of secondary impression :

Answer 5

dental stone

Question 6

what is the difference between stock trays used for dentulous patients and stock trays used for edentulous patients ?

Answer 6

• height of dentulous stock tray is greater to accommodate teeth

-edentulous tray has a protruding L shaped handle to reach into the oral cavity

-dentulous trays are square in shape while edentulous ones are more rounded

Question 7

foam trays are used in :

Answer 7

children

Question 8

which type of material is used in perforated trays ?

Answer 8

material requiring mechanical means of retention . COMPOUND

Question 9

mode of registration ( or basically what function the patient should be doing when taking the impression ) of minimal pressure impression taking ?

Answer 9

at state of relative rest

Question 10

which tray is used when taking a minimal pressure impression technique ?

Answer 10

perforated tray ( to relieve any pressure) with spacer ( customized for this specific patient)

Question 11

what kind of impression material is used in minimal pressure impression technique ?

Answer 11

low viscosity impression material

Question 12

mode of registration of muco-compressive impression technique ?

Answer 12

at function ( under biting force)

Question 13

what kind of tray is used when muco-compressive impression technique is employed ?

Answer 13

non-perforated without spacer , with occlusion rims

Question 14

what type of impression material is used for muco-compressive impression technique ?

Answer 14

viscous impression material

Question 15

how is selective pressure impression technique beneficial to denture stability both at rest and during function ?

Answer 15

the impression is taken both at rest and under pressure depending on the area . so the denture is very well adapted for both . minimal pressure impression technique on the other hand , only takes into account the patients anatomy at rest , which is why it could be unstable when in function. muco-compressive impression technique suffers from the same issue but opposite ( stable under pressure , not stable at rest )

Question 16

which impression technique covers the max area and results in better force distribution when denture is installed?

Answer 16

muco-compressive impression technique

Question 17

Which type of material is used for perforated trays ?

Answer 17

alginate and rubber base

Question 18

stability of a denture is dependent on ___

Answer 18

secondary impression

Question 19

indication for minimal pressure impression :

Answer 19

flabby ridge

Question 20

which kind of tray reduces bulk of impression material and why is this beneficial ?

Answer 20

special tray , this is important because it makes it possible to have uniform shrinkage

spercial tray is also :
-more comfortable for patient
-has more accurate border contour
-uses less impression material

Question 21

why is thr border of the special tray 2mm short of the full depth of vestibule ?

Answer 21

to all for continous adaptation of border to soft tissue (peripheral seal) by allowing for modelling of impression material/ intimate contact /shaping of flexible material that wraps around

Question 22

why is the process of boxing important ?

Answer 22

-preserves borders of impression
-thickness of base of cast can be controlled
-time and material is conserved
-permits vibrating the stone material into the impression

Question 23

non perforated trays are used alongside which type of material?

Answer 23

materials having adhesion properties to tray

Question 24

agar agar requires use of which tray ?

Answer 24

water cooled trays

Question 25

disadvantages of using minimal pressure impression technique ?

Answer 25

-denture not stable at function
-sparating medium on using plaster Imp

Question 26

disadvantages of using muco-compressive impression technique :

Answer 26

-denture not stable at rest

-continious pressure

-increases bone resorption

-decreases blood supply

Question 27

advantages of selective pressure impression technique ?

Answer 27

-stability during both rest and function

-automatic relief

-pressure to primary bearing areas

Question 28

advantages of acrylic resin special tray :(self curing)

Answer 28

-easily constructed
-more rigid than shellac
-accept border tracing material
-easily trimmed

Question 29

advantages of using a spacer:

Answer 29

-allows for even thickness for impression material to rest on

-aid in relief when used with selective impression technique