PFM Crown Restorations Flashcards
Indications for PFM
- Loss of dental structure (where a more conservative prep is not indicated)
- Esthetics
- Surveyed crown
- Malocclusion
- FDP (bridge)
- Endodontically treated tooth (weakened dental structure)
Contraindications for PFM
- active caries or perio disease
- young patients , pulp exposure
- when a more conservative prep is a reliable option
3 advantages to PFM
- strong restoration - helps keep tooths integrity (compared to inlays and onlays)
- Esthetics (compared to a FMC)
- permits correction of axial form (for RDP tx)
2 disadvantages to PFM
- Increased removal of dental structure (compared to inlays/ onlays and FMC)
- Subgingival finish line on the anterior segment to achieve esthetics (compared to all ceramic crowns) (risk of perio)
Know the ideal measurements for PFM on anterior and posterior
Anterior:
1 mm margin
1.5 mm axial wall
1.5-2 mm occlusal
Posterior:
1 mm margin
1.5 mm axial wall
1.5- 2 mm occlusal ( 1.5 non- functional 2 mm functional)
PFM axial and incisal wall metal coping and porcelain amounts
Axial wall:
0.3 mm metal coping
1-1.2 mm porcelain
Incisal edge:
0.3 mm metal coping
1.2 - 1.7 mm porcelain
What to do if you want a more conservative prep
metal occlusion (as thin as 1 mm)
What are pros and cons of metal occlusion with a PFM
Stronger occlusal surface (indicated for bruxism)
Indicated when limited interocclusal clearance
compromised esthetics
Metal occlusion anterior and posterior measurements
Anterior:
Cingulum >/= 1 mm metal
Posterior:
Functional cusp 1.5 mm
Non functional cusp >/= 1 mm metal (still has porcelain)
PFM finish line prep
1mm deep chamfer
If you have inadequate axial reduction you have
inadequate porcelain thickness for esthetics
may cause over-contoured restoration
undercuts- no path of insertion
Where is the bevel placed on a PFM prep
1.5 mm bevel on functional cusp
