Pfm

Question 1

Metal-Ceramic Restoration

Answer 1

Metal-Ceramic Restoration is an artificial crown used to
cover the surfaces of the clinical
crown with metal substructure
and porcelain veneer.

Porcelain fused to metal
restoration (PFM).
Consist of a ceramic layer bonded to
a thin cast metal coping that fits
over the tooth preparation.

Can be either
Full veneered: having all
surfaces faced with porcelain.
Veneered: having porcelain
on facial surface with some of
other surfaces not covered

Question 2

Strength of opfm

Answer 2

Metal-ceramic restorations have greater strength than restorations made of
ceramic alone

Question 3

Advantages

Answer 3

1. Increase strength compare with ceramic and increase aesthetic
   compare with metal.
2. Good retention and resistance.
3. Easy correction of the axial wall
4. Better margin fit
5. Less tooth structure removal compare to ceramic crowns and
   more than metal crown.

Question 4

Disadvantages

Answer 4

Increase tooth preparation to accommodate both metal and
porcelain.
2. Difficult shade matching.
3. Possibility of porcelain fracture
4. Expensive compare with metal ??? New ceramic material
more cost.
5. Subgingival labial margin may cause gingival irritation

Question 5

Indications

Answer 5

The same for full metal crown but for teeth require
aesthetic.
1.In case of extensive tooth destruction as a result of caries,
trauma, or existing previous restorations.
2.When superior retention and resistance is needed.
3.In case of an endodontically treated tooth.
4.To correct minor mal-inclinations of teeth.
B. When opposing other porcelain surfaces.

In patient with active caries or untreated periodontal disease.
2. When caries extend gingivally, as that the finish line cannot be
made.
3. In young patient with large pulp chamber because of the high
risk of pulp exposure.
4. Where a more conservative restoration can be made.

Question 6

Silicone Index

Answer 6

Silicone Index
Made before tooth preparation

When the prepared tooth is
badly decayed or Broken down,
Index made on waxed Up
diagnostic cast.

Facial Index
This index gives a better indication
of the entire facial surface reduction mesiodistally.
 Midsagittal Index
This index gives a better indication
of overall reduction, including the
incisal and lingual aspects, but it
does not provide any information
about the facial reduction
mesiodistally

Question 7

Steps of Preparation

Answer 7

Steps of Preparation
1) Labial-Axial Reduction.
2) Incisal Reduction.
3) Lingual- Axial Reduction.
4) Checking the reduction.
5) Finishing.

Question 8

Labial Axial Reduction

Answer 8

Should be reduce in 2 planes :
1 plane parallel with path of Insertion
1 plane parallel with incisal 2/3 of facial
surface

The first step is the placement of depth
orientation Grooves ( 1.2mm ) that
should be cut in two planes

Question 9

Labial Incisal depth
Bur
Margin

Answer 9

Incisal part - (2mm) depth orientation
grooves
Align the Flat-end Tapered Diamond with the incisal portion of the facial surface
Make at least two vertical cuts in the incisal portion of the facial surface
• These will be made to the full diameter of the diamond, fading out at the
“break”, where the curvature of the facial surface is greatest.
Gingival reduction
Sink the side of the diamond into the mesiodistal center of the facial
surface parallel with the gingival portion of the tooth. Repeated at least twice, ensure the same teeth alignment. For aesthetic reason, the margin is ultimately to be flush with the gingival
crest, or slightly subgingival
• However (for preclinical course), it is recommended to make the margin
0.5mm occlusal to the gingival margin

Inadequate incisal reduction results in poor incisal
translucency
In between groove tooth structure removal.(1.2-1.4mm)
Achieve a shoulder finish line (1.2mm )
The reduced facial surface should follow the curvature of the facial surface of the adjacent unprepared teeth.
Be sure that the gingival segment of the labial reduction extends well into the proximal surface result in wing
formation.
•1.0 mm lingual to the proximal contacts

Question 10

What is the benefit of this wing?

Answer 10

 Preserve the tooth structure
 Add some torque resistance to
the preparation
 The shoulder must be
extended lingual to the contact
to permit an adequate bulk of
interproximal porcelain for
good esthetics

Question 11

Lingual reduction:

Answer 11

Has 2 directions:
1) Lingual Fossa (cingulum Part) .- cingulum Part ): Using Football
shaped diamond
oHold the shaft of the bur parallel to the lingual surface to avoid over-reduction.

oMinimum of 0.7 mm of clearance with the
opposing teeth.
oThe lingual surface that will have a
ceramic veneer should have a minimum
of 1.0 mm of clearance.

Torpedo diamond is used to reduce the
lingual surface, simultaneously forming a
chamfer finish line (0.5mm).
• The lingual axial wall should be parallel
with the cervical one-third of the facial
surface.

2) Gingival Part .

Two opposing surfaces, each with a 3 degree inclination= 6o
degree.

Question 12

Posterior Metal-ceramic Crowns

Answer 12

Steps of Preparation
1) Occlusal Reduction
2) Labial-Axial Reduction.
3) Lingual- Axial Reduction.
4) Checking the reduction.
5) Finishing.

Question 13

Occlusal reduction of posterior pfm

Answer 13

Occlusal Reduction:
• The occlusal surface to to be covered with
porcelain, the depth-orientation grooves should be:
2.00 mm deep on the functional cusps (maxillary
lingual and mandibular facial cusps) and 1.5 mm
on the non- functional cusp.

The depth-orientation grooves: will be 1.5 mm if the cusp is to be covered by metal only, and 2.0 mm if it will be veneered with porcelain.

Depth Orientation Groove :
a. Gingival Half.
b. Occlusal Half.
Gingival Half. With a shoulder of 1.2 mm

Preparation of Lingual Reduction
Torpedo Diamond.
Achieve a Chamfer Finish Line (0.5mm)