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Wednesday, July 20, 2011

Anterior PMF(Porcelain Fused to Metal) Crown Restorations-Restorative Dentistry Lecture note

PFM (anterior) Crown Restorations
Advantages

1.       Stronger than all ceramic
2.       Superior marginal fit over all ceramic
3.       Better esthetic than cast restoration

Disadvantages

Preparation is not conservative as cast restoration

Steps

·         depth orientation grooves
·         incisal reduction
·         axial reduction
·         marginal placement
·         finishing

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

Axial reduction

Labial 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.
Lingual reduction:
·         Depth of reduction is 0.7mm.done by
·         1-round bur
·         2-foot ball
·         3-wheel.  4-turbido
·         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



Click here to Download Compare and Contrast among FullCrowns, PFM anterior, PFM posterior, Three quarter anterior and Three QuarterPosterior

Key Words : Crown restorations, Porcelain fused to metal crowns, Ceramic fused to metal crowns, Prosthetic dentistry lecture note

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