5/26 - Custom Tray, 298-302

Question 1

how far to extend custom tray

Answer 1

3 mm below gingival crest

Question 2

how many layers of wax to use for custom tray? this is equivalent to what?

Answer 2

2 layers

this is equivalent of 3 mm of PVS

Question 3

dimensions of tissue stops on custom tray

Answer 3

3x3 mm

Question 4

how many tissue stops should be placed on custom tray

Answer 4

3 - tripoded on non-functional cusps and incisal edges

Question 5

where to place tissue stops on custom tray

Answer 5

non functional cusps and incisal edges

Question 6

when creating custom tray, should you squish the wax real flat

Answer 6

NO! you’ll use the 3 mm thickness

Question 7

what should you place on pink wax to help with custom tray relief once material is cured (per grady)

Answer 7

small amounts of vaseline

Question 8

how should you cut the Triad material to aid with forming the tray

Answer 8

down the middle creating a horshoe shape

Question 9

what should you do to custom tray to prevent material from flowing out the back of the tray? what does this do

Answer 9

create an extension that covers the distal aspect of the last tooth. this allows for capture of distal margin of posterior prep

Question 10

how should you form handle when making custom tray for mandibular arch

Answer 10

straight up and a little out

Question 11

how many times will you bake tray? what happens at each bake?

Answer 11

2x2 minute bakes

1st 2 minutes: just place it in with model and pink wax

2nd 2 minutes: remove model and pink wax and just place in custom tray

Question 12

what should you do after baking custom tray

Answer 12

feel with fingers to remove rough spots and finish the rough edges

Question 13

why do we have to smooth out the custom tray

Answer 13

it can hurt patient (cutting, etc.)

Question 14

T/F: if you wouldn’t place it in your mouth, do not place in patient’s mouth

Answer 14

TRUE

Question 15

what should the inside of the tray be painted with for the impression material used?

Answer 15

uniform coat of adhesive

Question 16

what are the mandibular nonfunctional cusps

Answer 16

lingual cusps

Question 17

why are custom resin trays used in elastomeric impression techniques

Answer 17

are more accurate in uniform, thin layers of 2-3 mm (shil)

Question 18

why do some authors advise against the use of stock trays

Answer 18

uneven bulk of impression material is conductive to distortion

Question 19

what is the mean difference between custom and stock trays

Answer 19

1 mm

Question 20

does tray space have an effect on dimensional accuracy of monophasic PVS impressions

Answer 20

NO

Question 21

are stock trays or custom trays provide more sufficient accuracy for single-tooth preps, particularly if PVS or polyether is used

Answer 21

stock trays (per shill)

Question 22

are the adhesives between different tray materials interchangeable

Answer 22

no

Question 23

bonding strength of adhesives with PVS materials can be improved by:
50% by ___
140% by ___

Answer 23

50%: adding perforations to tray

140%: roughening inner surface of acrylic resin tray with 80 grit silicon carbide paper

Question 24

per shill, why should we not use petrolatum? what should be used instead

Answer 24

the waxy layer on the inner surface will diminish bonding by the tray adhesive applied before placement of impression material, resulting in distortion of impression.

use aluminum foil over wax and stone cast to provide separation

Question 25

should the tray touch retromolar areas

Answer 25

yes

Question 26

tray should be prepared how many hours in advance of making impression

Answer 26

at least 6 hours (since it could shrink as much as 8%)

Question 27

significant linear changes occur during the first ___ of tray fabrication and continue for up to ___

Answer 27

40 minutes; 6 hours

Question 28

how can an acrylic resin tray be stabilized against further shrinkage and distortion

Answer 28

boiling it before placing impression material

Question 29

should elastomeric impressions be stored in moist environment

Answer 29

no bc acrylic resin tray may imbibe water and distort