PFM crown preparation Flashcards
1
Q
What are indications for a PFM crown?
A
- Teeth that require complete coverage
- Require considerable attention to esthetics
- Bridge retainers
- Incorporation of occlusal or cingulum rests make it great for RPD abutments
2
Q
What are contraindications for a PFM crown?
A
- Pts whose mouth preparation has not been completed
- Young pts with large pulp chambers
- When a more conservative approach would suffice
- Whenever max esthetics is indicated and feasible
3
Q
What are advantages of a PFM crown?
A
- Permits easy correction of axial form
- Can be useful in making alterations to occlusal form
- Preparation is often less demanding on the operator than partial coverage options
- Retention and resistance qualities can ve excellent
4
Q
What are disadvantages for PFM?
A
- Significant tooth reduction is necessary
- Subgingival margin is often required on the facial aspect
- Increased risk for contact dermatitis with some metals
- More difficult to achieve premium esthetics than with all-ceramic restorations
- Porcelain fracture risk
- Labor intensive nature of the restoration can lead to higher lab expenses
- Feldspathic porcelain can be abrasive to opposing tooth
5
Q
With a PFM where should the heavy chamfer be placed?
A
-Facial with a lighter chamfer on the lingual
6
Q
What is the incisal reduction of an anterior PFM?
A
-2.0 - 2.5 mm
7
Q
What is the facial axial reduction?
A
-1.2 - 1.7 mm
8
Q
What is the lingual concavity reduction?
A
1 mm metal
-1.5 mm porcelain
9
Q
What is the lingual chamfer reduction?
A
-.5 - 1 mm
