Anterior PMF Porcelain Fused to Metal Crown Restoration
PFM (anterior) Crown Restorations
- Stronger than all ceramic
- Superior marginal fit over all ceramic
- Better esthetic than cast restoration
- Preparation is not conservative as cast restoration
- depth orientation grooves
- incisal reduction
- axial reduction
- marginal placement
Occlusal reduction (posterior) or incisal reduction (anterior)
- We do depth orientation grooves for even thickness reduction then remove tooth structure in between
- We use flat-end tapered diamond bur to do 2mm reduction
- We do depth orientation grooves in two planes to avoid pulp exposure
- Parallel to gingival 1/2
- Parallel to incisal 1/2
- We use flat end tapered diamond bur to do 1.5 mm reduction to do shoulder with bevel (bevel is done to decrease area of exposed cementum.
- We use enamel chisel, such as hachet or biangle chisel to remove undermined edge of tooth structure. We use the chisel also to produce smooth finish line.
- Wings: is left standing in each proximal area, lingual to the proximal contact so the metal won’t display.
- It1- preserves tooth structure 2-and adds some torque and rotational resistance.
- Depth of reduction is 0.7mm.done by:
2,3 are used above the cingulum
1,4 below the cingulum to make heavy chamfer finish line.
Proximal wall reduction:
- Initial reduction is done with long needle diamond then a small diameter tapered round end diamond bur is used to insure chamfer finish line.
- 2_3 degree taper on each side.
Gingival marginal placement:
- The end cutting bur no. 957, but is only used to smoothen the SHOULDER finish line and to move the shoulder subgingivally But usually we don’t use it.
- The internal angle should be rounded to reduce stress concentration