Quiz 2 Review

Question 1

what is the most effecient way to adjust zirconia?

Answer 1

use fine diamonds

the coarsest diamond you want to use is medium

Question 2

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

Answer 2

1/2

Question 3

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

Answer 3

amount of coronal tooth structure remaining

Question 4

___ is a solid transparent plastic made of polymethylmethacrylate

Answer 4

lucite

Question 5

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

Answer 5

leucite

Question 6

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

Answer 6

leucite

Question 7

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

Answer 7

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

Question 8

what is transformation toughening?

Answer 8

• 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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

what order of abrasives should you use when adjusting zirconia?

Answer 11

start with medium, then fine, then extra fine

Question 12

which is thinner, accufilm or madame butterfly?

Answer 12

accufilm

Question 13

of accufilm and madame butterfly, which shows relative intensities?

Answer 13

madame butterfly

Question 14

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

Answer 14

accufilm

Question 15

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

Answer 15

madame butterfly

Question 16

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

Answer 16

gold

madame butterfly is easier to read on gold

Question 17

what order should you adjust a crown/temp?

Answer 17

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

Question 18

how should you adjust proximal contacts?

Answer 18

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

Question 19

what are some characteristics of zirconia 3y-tzp?

Answer 19

• yttria partially stabilized
• soft cast
• polycrystalline
• tetragonal zirconia

Question 20

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

Answer 20

• ceria stabilized tetragonal
• zirconia polycrystalline with alumina nanocomposites

Question 21

porcelain is a ceramic

zirconia is a ceramic

but ___ is not a ___

Answer 21

zirconia is not a porcelain

Question 22

describe the 3 zirconia crystalline phases

Answer 22

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

Question 23

what is the basic manufacturing process for zirconia?

Answer 23

• 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

Question 24

what is the basic manufacturing process for lithium disilicate?

Answer 24

pressed and hard machined

Question 25

what do build-ups do?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

potential for fracture

greatest potential for iatrogenic failure

Question 28

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

Answer 28

• 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

Question 29

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

Answer 29

zinc-free amalgam

zinc in the amalgam causes it to creep

Question 30

what margin type can you not use with lithium disilicate?

Answer 30

chamfer

Question 31

which margin type should you use with gold?

Answer 31

chamfer

Question 32

what are the advantages of a chamfer margin?

Answer 32

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

Question 33

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

Answer 33

rounded shoulder

Question 34

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

Answer 34

gold or PFM

Question 35

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

Answer 35

• zirconia
• bulk material

Question 36

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

Answer 36

• you should use relyx unicem
• avoid glass ionomer cements