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Digital Dentistry 2 > L4 ZIrconia > Flashcards

L4 ZIrconia Flashcards

1
Q

ceramics

A

man made solid objects formed by baking non-metallic inorganic minerals at high temperatures

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2
Q

zirconia (makeup)

A

zirconium oxide + yttrium oxide

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3
Q

transformation toughening

A

tetragonal –> monoclinic

increase in size (3-4%)

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4
Q

types of strength transformation

A

tensile –> compressive

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5
Q

ability of zirconia to arrest crack propagation by changing its phase at the crack’s edges from _____ to _____. thus, the size of the molecules ____, and ____ stresses are replaced by _____ stresses

A

tetragonal
monoclinic
increase
tensile
compressive

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6
Q

flexural strength of zirconia compared to enamel + dentin

A

higher

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7
Q

fracture toughness of zirconia compared to enamel and dentin

A

higher

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8
Q

why zirconia?

A
  1. the widespread use of CAD/CAM
  2. less expensive and less time consuming (when compared to PFM restorations)
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9
Q

monolithic zirocnia

A

classified by the amount of yttria

the ENTIRE crown is made of zirconia (no porcelain)

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10
Q

layered zirconia

A

multiple different layers

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11
Q

the key to classifying dental zirconia is _____

A

the yttria content

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12
Q

monolithic zirconia 3Y - yttria content

A

3 mol %

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13
Q

monolithic zirconia 3Y - tetragonal vs cubic

A

> 85% tetragona
<15% cubic

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14
Q

monolithic zirconia 3Y - strength and translucency

A

high strength
low translucency

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15
Q

monolithic zirconia 3Y - good to use for…

A

posterior single unit crowns
FDP

DO NOT USE in highly esthetic areas

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16
Q

monolithic zirconia 3Y - preparation

A

0.5-0.8mm margin - rounded shoulder or heavy shamfer

0.6mm occlusal reduction (manufacture)
0.7-1mm occlusal reduction (studies)

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17
Q

monolithic zirconia 4Y - yttria content

A

4 mol%

18
Q

monolithic zirconia 4Y - tetragonal vs cubic

A

75% tetragonal
25% cubic

19
Q

monolithic zirconia 4Y - strength and translucency

A

lower strength compared to 3Y
acceptable translucency

20
Q

monolithic zirconia 4Y - good to use for…

A

single unit restorations (premolar area)

21
Q

monolithic zirconia 4Y - preparation

A

0.8-1mm margin
1mm occlusal reduction (manufacture)
1.2mm occlusal reduction (studies)

22
Q

monolithic zirconia 5Y - yttria content

A

5 mol%

23
Q

monolithic zirconia 5Y - tetragonal vs cubic

A

<50% tetragonal
>50% cubic

24
Q

monolithic zirconia 5Y - strength and translucency

A

low strenght
high translucency

25
Q

monolithic zirconia 5Y - good to use for

A

anterior crowns

26
Q

monolithic zirconia 5Y - preparation

A

1mm margin
1mm occlusal reduction (manufacture)
1.5mm occlusal reduction (studies)

27
Q

layered zirconia - makeup

A

porcelain fused to zirconia (PFZ)

28
Q

core and outer layer of layered zirconia

A

core = 3 mol% zirconia
outside = porcelain

29
Q

strength and translucency of layered zirconia

A

high strength
low translucency

30
Q

dimensions of core and porcelain (layered zirconia)

A

0.6mm core
1.2mm (<2mm) porcelain

31
Q

what happens if there is more than 2m of unsupported porcelain?

A

porcelain chipping

32
Q

multi-shade layered zirconia

A

yttria content is the same throughout
restoration has different shades!

33
Q

multi-yttria layered zirconia

A

the yttria content is different throughout
made of same shade

DIFFERENT TRANSLUCENCIES

34
Q

strength and translucency of multi-yttria layered zirconia

A

variable strength
variable translucency

because of different yttria contents!

35
Q

in theory, where should the stronger zirconia go in multi-yttria layered zirconia

A

stronger phase zirconia at cervical part because it increases fracture resistance

36
Q

in reality, what happens when the weaker zirconia phase is at the occlusal part?

A

decreases fracture resistance

37
Q

when should you use sodium hydroxide in zirconia cementation?

A

after trying in restoration

37
Q

when should you use sodium hydroxide in zirconia cementation?

A

after trying in restoration

38
Q

why use sodium hydroxide for zirconia cementation?

A

because zirconia has a high affinity to salivary proteins so cleaning it with sodium hydroxide after the try in is necessary

38
Q
A
39
Q

bonding protocol for zirconia

A

APC concept

  1. air abrade
  2. phosphate monomer
  3. cement
40
Q

what kind of cement should be used for zirconia?

A

dual or self/chemical cure

Digital Dentistry 2 (5 decks)

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