Metal and All-Ceramic Preparations Flashcards
A metal-ceramic crown is also known as a:
PFM
A crown that has a metal core with porcelain baked onto the metal core:
PFM (metal-ceramic)
This type of crown takes the strength of metal and combines it with the tooth matching esthetic ability of procelain:
PFM (metal-ceramic)
Indications for PFM include:
- When opposing tooth is:
- When a high level of ____ is needed
- When preparation is ____
- _____ & other ___ fixed restorations
- porcelain/ceramic
- esthetics
- unusual
- bridges; longspan
Advantages of PFM crowns:
________ due to the porcelain baked onto the metal coping
Natural appearance
Advantages of PFM crowns:
More _____ than all-ceramic crowns
resistant to fracture
Advantages of PFM crowns:
Greater ____ due to metal core than all-ceramic crowns
strength
Advantages of PFM crowns:
________- meaning it can have whole crown layered with porcelain to it can can metal occlusal with porcelain facing on buccal only.
Design flexibility
In the case of a PFM crown, metal added to the ____ adds strength
occlusal
Advantages of PFM crowns:
____ to multiple types of _____
adaptable; margin designs
What are the types of margin designs a PFM crowns can adapt to?
- chamfer
- shoulder
- shoulder with bevel (not common)
To accomodate beh requirements and benefits of using a PFM crown, the preparations need to be designed in particular ways including
- To accomodate ___
- To provide ____
- To allow for ___
- To decrease ____ associated with PFM crown design
- metal and porcelain
- optimum strength
- optimum esthetics
- gingival problems
PFM porcelain components include:
- opaque porcelain
- body porcelain
- incisal porcelain
- shoulder porcelain
What is the minimal metal thickness in a PFM crown:
0.3-0.5 mm
In a PFM crown, porcelain thickness contributes to:
maximizing esthetics
In a PFM crown the metal coping in the veneered areas = _____ while the metal coping in the unveneered areas = ____
veneered= 0.3-0.5 mm
unveneered= 0.8-1.0mm
In a PFM corn, the opaque porcelain = _____ while the shoulder porcelain = _____ while the gingival, body, and incisal porcelain = _____
opaque= 0.1-0.2 mm
shoulder= 0.8mm
gingival/body/incisal= 0.8-2.0 mm
In a PFM crown, what is the metal occlusal reduction?
In a PFM crown, what is the porcelain occlusal reduction?
1.5 mm
2.0 mm
In a metal-ceramic crown, two plane reduction allows for:
even thickness of material
In a PFM, what does the abscence of two plane reduction possibly result in?
endanger the pulp
With thinner areas in a PFM, this will decrease the ___ because it does not allow proper porcelain coverage
esthetics
In a PFM crown, what allows for porcelain esthetics to be carried into the contact regions for maximum esthetics?
continuing shoulder margin into and through the inter-proximal areas before thinning to a chamfer
In a PFM, ____ finish lines provide greater space for an esthetic thickness of metal and porcelain without having to over-contour the crown restoration
shoulder
In a PFM crown, a paper shoulder margin with appropriate depth allows the crown margins to be contoured for optimal:
gingival health and esthetics
Why is a shoulder with a rounded line angle preferred for PFM crowns? (3)
- easier to prepare than a sharp 90 degree line angle
- if crown needs to be milled, a mill cannot create a 90 degree finish line angle
- Less stress on the tooth with a rounded shoulder finish
What is the shoulder with a rounded line angle finish line referred to in PFM crowns?
modified shoulder margin (typical shoulder is 90 degrees and here we are rounded)
Type of PFM crown margin design in which the porcelain is stopped with some metal showing at the margin:
metal collar
What is the advantages to doing a metal collar PFM metal crown margin design?
Ease of fabrication & precise fit (if margin cannot be large enough to accomodate both metal and porcelain)
In a PFM crown preparation, if margin is deep subgingival, ____ allows for less material and less likely and over contoured crown which would create gingival problems:
metal collar
With a metal collar PFM crown margin, what is the design of the margin?
Heavy chamfer or shoulder (can use shoulder with bevel)
What is the margin depth when preparing a metal collar PFM crown margin design?
1.2 mm ideally but can accommodate smaller
Type of PFM crown margin design in which the metal is thinned to a fine line that is barely visible:
Disappearing metal