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Flashcards in Quiz 2 Review Deck (36)
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1
Q

what is the most effecient way to adjust zirconia?

A

use fine diamonds

the coarsest diamond you want to use is medium

2
Q

___ or more missing coronal tooth structure warrants a build-up

A

1/2

3
Q

what is the most significant factor in long-term success when it comes to teeth restored with build-ups?

A

amount of coronal tooth structure remaining

4
Q

___ is a solid transparent plastic made of polymethylmethacrylate

A

lucite

5
Q

___ is a white or gray feldspathic mineral composed of potassium and aluminum silicates

A

leucite

6
Q

of lucite and leucite, which one has crystals that increase resistance to crack propagation in ceramics, and provide the strengthening component of ceramics?

A

leucite

7
Q

which company produces most of the zirconia powder in the world and why is it important to know that?

A
  • Tosoh corp. - they produce 98% of the world’s zirconia
  • quality control! it is the purest zirconia
8
Q

what is transformation toughening?

A
  • a property of zirconia that makes it an ideal material
  • when a crack forms in zirconia, a crystalline phase change is induced near the point of the crack, and the zirconia in this area transforms from tetragonal to monoclinic, which takes up the most volume, so the crack doesn’t get any bigger
9
Q

why is it critical that the abrasive used to adjust zirconia is harder than the zirconia itself?

A

it doesn’t cause the phase transformation from tetragonal to the other forms - it just cuts the material away instead

10
Q

what are some things you want to avoid when adjusting zirconia?

A

don’t apply too much pressure, don’t go too quick, don’t cause too much friction (aka heat)

all of these things can damage the zirconia

11
Q

what order of abrasives should you use when adjusting zirconia?

A

start with medium, then fine, then extra fine

12
Q

which is thinner, accufilm or madame butterfly?

A

accufilm

13
Q

of accufilm and madame butterfly, which shows relative intensities?

A

madame butterfly

14
Q

of accufilm and madame butterfly, which can give false negatives?

A

accufilm

15
Q

of accufilm and madame butterfly, which tends to give better marks in moist environments?

A

madame butterfly

16
Q

which material generates the worst marks with articulation ribbon? of accufilm and madame butterfly, which is easier to read on this material?

A

gold

madame butterfly is easier to read on gold

17
Q

what order should you adjust a crown/temp?

A

start with proximal contacts, then esthetics, then margin, then occlusion

18
Q

how should you adjust proximal contacts?

A

you want to sneak up on the contact so you don’t overpolish and lose the contact

19
Q

what are some characteristics of zirconia 3y-tzp?

A
  • yttria partially stabilized
  • soft cast
  • polycrystalline
  • tetragonal zirconia
20
Q

what are some characteristics of zirconia Ce-TZP/A?

A
  • ceria stabilized tetragonal
  • zirconia polycrystalline with alumina nanocomposites
21
Q

porcelain is a ceramic

zirconia is a ceramic

but ___ is not a ___

A

zirconia is not a porcelain

22
Q

describe the 3 zirconia crystalline phases

A
  • cubic = smallest, weakest
  • tetragonal = intermediate, strongest, this is the ideal phase
  • monoclinic = largest
23
Q

what is the basic manufacturing process for zirconia?

A
  • hard and soft processing
    • partially cintered, green state = soft machining
    • remember, green state is larger than the final product because it shrinks when it is cintered, so it needs to be calibrated prior to cintering
    • hard machining means fully cintered
24
Q

what is the basic manufacturing process for lithium disilicate?

A

pressed and hard machined

25
Q

what do build-ups do?

A
  • enhance connection to the tooth structure
  • minimize amount of restorative material (very important with gold crowns)
  • provide thermal insulation
  • acts as a chemical barrier
26
Q

besides the amount of coronal tooth structure remaining, what else correlates with long-term success of indirect restorations?

A

favorable occlusal scheme in final restoration - this reduces lateral loading and ultimately enhances restorative longevity

27
Q

why don’t we put pins in all the time?

A

potential for fracture

greatest potential for iatrogenic failure

28
Q

we use composite resin as a restorative and foundation material very often. what are some of the disadvantages?

A
  • it shrinks
  • higher moisture absorption vs. amalgam
  • higher coefficient of thermal expansion
  • these disadvantages are pretty much negated though because you can get a very nice restoration using composite resin
29
Q

if you were doing a build-up in a moist environment, what would be the best material of choice?

A

zinc-free amalgam

zinc in the amalgam causes it to creep

30
Q

what margin type can you not use with lithium disilicate?

A

chamfer

31
Q

which margin type should you use with gold?

A

chamfer

32
Q

what are the advantages of a chamfer margin?

A
  • easy to read
  • relatively easy to prepare
  • allows a reasonable bulk restorative material
33
Q

it is easier to put a lip (ski jump) on which type of margin?

A

rounded shoulder

34
Q

rounded shoulder margins can be used with any restorative material other than what?

A

gold or PFM

35
Q

___ is the only ceramic material where you can get away with a chamfer margin; all other ceramics need more ___

A
  • zirconia
  • bulk material
36
Q

what cement should you use for posts? what cement should you avoid?

A
  • you should use relyx unicem
  • avoid glass ionomer cements