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Fixed Prosth 2 > Metal Ceramics > Flashcards

Metal Ceramics Flashcards

1
Q 
\_\_\_\_\_\_\_\_\_ crown 
consists of a metal casting or coping 
which fits over the prepared tooth 
and has ceramic fused to the metal.
This combines the strength and 
accuracy of metal with the esthetics 
porcelain can provide.
A

Porcelain Fused to Metal (PFM)

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2
Q 
-Designed with thickness to support the 
porcelain
-Design to support occlusal and proximal 
contacts
-Designed with extensions to support 
porcelain
-Margin design to adapt perfectly to 
margins and support the porcelain if 
porcelain margins are placed
A

Metal Coping

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3
Q

The Ledge of metal to support a ____ degree Metal-

Ceramic finish

A

90 degree

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4
Q

How thick should the metal coping be to support the porcelain?

A

.3-.5mm thick

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5
Q

metal needs to be at least ______ thick for noble metals

A

0.3 – 0.5mm

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6
Q

metal needs to be at least _____ thick for base metals

A

0.2mm

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7
Q

-if porcelain is more than ____ thick, a fracture of the porcelain becomes a higher risk

A

2 mm

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8
Q

Ideal of ______ thick porcelain means that the metal design will vary and change
to allow for this uniform thickness

A

1 – 1.5 mm

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9
Q

Masks the metal

Established the metal-ceramic bond

A

Opaque porcelain

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10
Q

Colors include dentin, enamel, translucent,

shoulder porcelains

A

Body porcelain

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11
Q

Final color match
Color modification once crown is complete
Lower fusing temp than body porcelains

A

Stains/Glazes

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12
Q

A high noble metal has at least _____ % gold

A

40%

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13
Q

The higher the gold content in a metal, the ____ the metal

A

Softer the metal

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14
Q

At least 25% noble metals but doesn’t have to be GoldPalladium – Silver
Palladium – Copper
Palladium – Cobalt
Palladium – Gallium
They are a compromise between the high noble metals and the base metals in
terms of cost and in density
The workability and fabrication can be similar to high noble
Because of less Gold, noble metals tend to have a higher strength and greater restistance
to deformation.

A

Noble metals

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15
Q

Nickel-Chromium
Nickel-Chromium-Beryllium
Cobalt-Chromium
Stiffer metal
Harder metal
Greater Sag resistance
Lowest Density – more difficult to cast and therefore more difficult to finish in
preparation for the porcelain and not a strong solder joints
This can also lead to high oxide formation and therefore problems with
bonding
Often the lowest cost and lowest quality of materials.
Higher likelihood of reaction if patient has metal allergy.

A

Base Metal

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16
Q

PFM crowns are layered with _____ porcelain
Relatively weak material
Wears opposing teeth at a very high rate

A

feldspathic porcelain

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17
Q

What happens to feldspathic porcelain when it is fired?

A

Shrinks

18
Q

What part of the feldspathic porcelain -Increases the Coefficient of Thermal Expansion
-Includes opacifiers and colorants

A

Glass Modifiers

19
Q

-Microabrasions from Metal finishing or from Air Abrasion create a
surface that allows for the interlocking of porcelain and metal
-These microabrasions also clean the surface
-These microabrasions also increase the surface area of the metal
-Finally, the microabrasions increase the “Wettability” of the
metal. This means the porcelain will flow over the metal
material better and therefore flow into the abraded surface

A

-Mechanical Interlocking

20
Q

-When done correctly, this oxide bond is so strong,
the _____ will break before the bond
gives away!

A

porcelain

21
Q

If the ____ is contaminated after firing, the bond will break

A

Oxide layer

22
Q

_____ the amount of Gold in the alloy, the lower the melting temperature

A

Higher

23
Q

Because some porcelains fuse at a higher temperature than the melting temp of the metal, _______ fusing ceramic is used.

A

low

fusing

24
Q

The occlusion between the natural teeth and PFM should put the natural teeth on the ___ portion of the PFm

A

Metal portion

25
Q

Occlusion should be ___ mm away from the porcelain finish line

A

1.5 mm

26
Q

Can you add porcelain/ceramic to PFM to close contact if it is open?

A

yes

27
Q

In maxilla, -If porcelain is on the occlusal, ___ mm of

reduction on the occlusal is necessary

A

2 mm

28
Q

-In maxilla, it is Ideal to have___ mm metal collar on the
lingual to support occlusal forces on
porcelain
-

A

3mm

29
Q

-To prevent fracture, ideally to make
occlusal complete _____
-Less reduction on an already short
tooth

A

metal.

30
Q

In the maxilla or mand that full coverage porcelain is used for esthetics more often?

A

Mand

31
Q

____ PFM margin

  • Slight subgingival placement for best esthetics
  • Great margin for esthetic zones
  • Requires special shoulder porcelain and additional technique
  • Uses high fusing aluminous porcelain
  • Need a good ceramist for this
  • Need 2 additional firings at a higher temperature
  • 90 degree angle for strength and sealed finish line
A

Porcelain Shoulder Margin

32
Q

_____ PFM margin
-This design is a more conservative tooth
preparation in cervical area
-Restoration design is easier for the lab to
fabricate
-Great for molars that have margins deep
sub-gingival
-Allows for multiple types of preparation finish
lines

A

Metal Collar Margin

33
Q 
\_\_\_\_ PFM margin
-Indicated for areas that 
the margin cannot be 
hidden under the 
gingiva
-Often metal copings are 
over contoured and 
thick at gingival area
A

Disappearing Margin

34
Q

-Cohesive Fracture is a bond failure due

to _____ or ______

A

traumatic incident or heavy

occlusion

35
Q

-Adhesive Fracture is the ______ of the

porcelain from the metal

A

de-lamination

36
Q

-The CTE of metal is slightly _____ than the CTE of porcelain

A

greater

37
Q

_________ is the biggest drawback to the PFM crown.

A

Fracture of the porcelain

38
Q
  • _______ of the PFM (metal to porcelain) is #1 reason for fracture
  • The second? _________
A

Poor design

OCCLUSION!!!

39
Q

-Strength comes from the _____ in a PFm

A

bond between the metal

and ceramic

40
Q

Do PFZs or PFMs need thicker connectors?

A

PFZ

Fixed Prosth 2 (12 decks)

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