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fixed 3 > metal ceramics and crowns with labial porcelain margins > Flashcards

metal ceramics and crowns with labial porcelain margins Flashcards

1
Q

what is a ceramic

A

A product made from a non-metallic inorganic material processed by firing at a high temp to achieve desirabled properties

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2
Q

what are the groups of dental ceramics

A

High fusion
MEdium Low fusion
Ultra low fusion

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3
Q

temp for high fusion ceramics

A

1290-1370 degrees C

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4
Q

temp for medium fusion ceramics

A

1090-1260 degrees C

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5
Q

temp for low funsions ceramics

A

870-1070

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6
Q

temp for ultra low fusion ceramics

A

less than 850

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7
Q

what dental ceramics are used for Dnture teeth and porcelain jacket crowns

A

High fusion

Medium fusion

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8
Q

what dental ceramics are used for metal-ceramic crowns

A

Low fusion

Ultra Low-fusion

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9
Q

what is feldspar made of

A

A naturally occuring glass with silicas, fluxes, and alumina neatly bound together

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10
Q

what does feldspar bind

A

all 3 forms of clay bodies together once fused at a high temp

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11
Q

how is Frit mad

A

materials of dental porcelain are heated to a high temp then cooled fast to cause glass to fracture

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12
Q

what are the chemicals of Feldspar

A

Potassium aluminum silicate orthoclase

Sodium aluminum silicate albite

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13
Q

what is the chemical in quartz

A

Silicon oxide

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14
Q

what is vitrification

A

Turning cystalline silica along with associated fluxes and modifiers into glass

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15
Q

what does porcealin turn into after vitrification

A

Ceramic body

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16
Q

what is the ceramic body made of

A

the refractory skeletal structure

feldspathic glass betwen the refractory particles

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17
Q

how is the refractory skeletal structure made in a ceramic body

A

through sintering and fusing processses to help it maintain shape

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18
Q

how is porcelain different than glass

A

Glass with a refractory internal structure

19
Q

do all porcelains have the same composition

A

No, have different ratios

20
Q

what are the types of dental porcelains for an MCC

A

Opaque porcelain
Body/dental porcelain
Incisal/enamel porcelain

21
Q

what does the opaque porcealin contain

A

Opacifying oxides

22
Q

can you see through body porcelain

A

Yes, it is translucent

23
Q

what is found in body porcelain

A

metalic oxides that give shade or base color selected

24
Q

how see through is the incisal/enamel porcelain

A

More translucent than body

25
Q

what are the dental porcelains mixed with

A

Water based glycerin continaing liqued

26
Q

how should enamel porcelain be added

A

over build it

27
Q

how should grind porcelain

A

Use stones or diamond burs only used to grind porcelain on a low speed

28
Q

how should shimstock feel when contact is good

A

Should drag when crown is seated, but if it holds it is too tight

29
Q

what wheels are used to adjust contact

A

Blue: course
Pink: medium
Gray: fine

30
Q

how to prep porcelain for a second bake

A

Clean in DI for 10 min

add porcelain to areas that are deficient

31
Q

advantage of Porcelain labial margin

A

Improve esthetics

Less plaque retention

32
Q

disadvantages of porcelain labial margin

A
  • Generally inferior margin adaptation compared to cast metal
  • decreased strength compared to metal
  • more time consuming
  • slight more expesnive than conventional MCC
33
Q

what are the techniques for porcelain labial margin fab

A

Platinum foil matrix tech
Porcelain wax technique
Direct lift technique

34
Q

what is the direct lift technique

A

Apply shoulder porcelain on margin and dry with tissue paper and brush excess with large brush

35
Q

advantage of direct lift technique

A

LEast time consuming

36
Q

disadvantage of direct lift technique

A

Shoulder porcelain needed

Slightly rough margins

37
Q

when were porcelain crowns first used

A

1903 ( over 100 yeras ago)

38
Q

what is the problem with cooling porcelain

A

causes the metal to distort ( low temp is desired)

39
Q

what chem is the major component of porcelain

A

SiO2

40
Q

why should you overbuild porcelain

A

account for voids

Shrinks 45-30%

41
Q

what color should shoulder porcelain be

A

should be opaque

42
Q

what holds more plaque, ceramic or metal retainers

A

metal

43
Q

what technique is generally used to pain porcelain on the margin

A

Direct lift technique

fixed 3 (4 decks)

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