Posterior metal ceramic crown

Question 1

How does the preparation for a metal ceramic crown differ a full veneer crown prep

Answer 1

Tooth prep for a metal ceramic crown requires further tooth tissue reduction in certain n areas to make space for the metal.

Question 2

What do we need to consider when preparing a metal ceramic

Answer 2

1. The tooth’s aesthetic importance
2. The tooth’s function
3. Condition of the opposing tooth
4. Is the tooth an annulment to a removable appliance
5. The patients parafunctional habits

Question 3

What does the amount of occlusal reduction for s metal ceramic crown depend on?

Answer 3

the crown design and porcelain coverage

Question 4

Describe the 2 different types of porcelain coverage we can get with a metal crown

Answer 4

1. Metal occlusal surface

2. Metal and porcelain occlusal surface

Question 5

How much occlusal reduction would we carry out for a metal occlusal surface

Answer 5

1mm non functional cusp

1.5mm functional cusp

Question 6

How much occlusal reduction would we carry out for a metal and porcelain occlusal surface

Answer 6

1.5mm non functional cusp

2mm functional cusp

Question 7

How much axial reduction do we need to carry out for a metal ceramic crown?

Answer 7

1.2mm shoulder margin

Question 8

Why do we need a 1.2mm shoulder margin when carrying out axial reduction

Answer 8

0. 5mm needed for thickness of the metal substructure (needed for strength)
1. 2mm for opaque porcelain (to mask underlying metal colour)
2. 5mm of aesthetic porcelain
   (0. 5+0.2+0,5=1.2)

Question 9

What problems can arise if we make our shoulder margin to thin?

Answer 9

1. Risk of constructed crown being too bulbous in shape leading to gingival inflammation
2. Crown could display a poor shade due to thin porcelain layer
3. Structural durability could be affected

Overall crown failure

Question 10

What is structural durability?

Answer 10

Is the relationship between the occlusal stress and material strength

Question 11

Which burr do we use to achieve our 1.2mm shoulder reduction

Answer 11

Flat ended long tapered diamond bur

Question 12

Describe a long tapered diamond bur

Answer 12

It possess a 6 degree taper
Has a flat cutting end
Diameter of 1mm

Question 13

What can we use to estimate the amount of axial reduction we need

Answer 13

1. The long tapered diamond bur has a diameter of 1mm

2. The small end of the packer is approx 1.5mm

Question 14

What can happen if we have a too large axial reduction

Answer 14

Can lead to weakening of the tooth structure and risk of irreversible plural damage or reduced retention and resistance

Question 15

Talk through the criteria for a metal ceramic crown

Answer 15

1. No undercuts
2. Well-defined recordable margins
3. Adequate occlusal reduction
4. Clearance of contact points
5. Adequate labial/buccal reduction for metal and porcelain
6. Adequate palatal reduction for metal
7. Finishing of preparation
8. No iatrogenic damage to adjacent teeth

Question 16

What should the buccal shoulder be for the mesio buccal cusp?

Answer 16

1.2mm

Question 17

What should the buccal shoulder be for the disco buccal palatal/lingual chamfer?

Answer 17

0.5mm