Full veneer crowns

Question 1

List some indications for crowns

Answer 1

1. To protect weakened teeth
2. Restore tooth to function
3. To improve/ restore aesthetics
4. Can be used as abutments for fixed prosthesis,

Question 2

Name the most suitable material for restoring dentition

Answer 2

Gold

Question 3

Why is gold the most suitable material for restoring dentition

Answer 3

1. Durable
2. Strong in thin sections
3. Does not wear the opposing tooth tissue
4. Biocompatible
5. Resistant to corrosion
6. Easy to adjust and polish

Question 4

What are some of the disadvantages of using golf to restore dentition

Answer 4

1. Expensive

2. Unaesthetic for some people

Question 5

List the principles of preparation

Answer 5

1. Allow room for adequate thickness of metal
2. Have retention and resistance form
3. No undercuts
4. Supragingival where possible
5. Chamfered margins
6. Be as conservative as possible

Question 6

Name the stages of crown preparation

Answer 6

1. Planar occlusal reduction
2. Axial reduction
3. Functional cusp bevel
4. Seating groove (not essential)

Question 7

What does planar occlusal reduction do

Answer 7

Provides structural durability

Question 8

What does axial reduction do?

Answer 8

Provides retention and resistance

Question 9

what does a functional cusp bevelling do?

Answer 9

Provides structural durability

Question 10

What does a seating groove provide?

Answer 10

Retention and resistance but it is not essential

Question 11

Name the different burs we may use when carrying out.a crown prep?

Answer 11

1. Chamfer burr
2. Fine needle point diamond
3. Long tapered shoulder burr
4. Ling pear shaped fissure burr
5. Topedo

Question 12

What is the chamfer bur made to do?

Answer 12

Used to give a round contour to the finish margins

Question 13

What is the diameter of the chamfer burr?

Answer 13

1mm

Question 14

What taper do we wish to achieve

Answer 14

A 0.5mm taper

Question 15

What is the fine needle burr used to do?

Answer 15

It is very fine and used to break the contact points

Question 16

What is a long tapered shoulder burr used to do?

Answer 16

On a metal ceramic preparation a labia shoulder is required and this has a flat base
A shoulder burr is used to create this

Question 17

What is the taper of a shoulder burr?

Answer 17

6 degrees (the ideal taper for retention and resistance)

Question 18

Whe is diamond fissure burr used?

Answer 18

When we want to use a shorter burr to reduce the occlusal surfaces with restricted access

Question 19

What is another name for the torpedo burr?

Answer 19

Rugby ball diamond

Question 20

What is the torpedo used to do?

Answer 20

Reduce the curve of the palatal aspect of incisors

Question 21

List the stages of preparation

Answer 21

1. Occlusal
2. Buccal
3. Lingual
4. Mesial
5. Distal

Question 22

What are we aiming for when carrying our occlusal reduction for a gold crown

Answer 22

1. 1mm occlusal clearance

2. Additional 0.5mm on the functional cusp

Question 23

Name the functional cusps in the upper arch

Answer 23

Palatal cusps

Question 24

Name the functional cusps in the lower arch

Answer 24

Buccal cusps

Question 25

Which burr do we use for the occlusal reduction and why

Answer 25

Short fissure burr as it has a diameter of approx 1mm

Question 26

Which burr do we use to reduce the functional cusp

Answer 26

chamfer burr

Question 27

How mcc do we need to reduce the functional cusp?

Answer 27

1.5mm

Question 28

How much axial reduction do we need to carry out?

Answer 28

MAX 0.5MM

Question 29

List the criteria we use to send assess our crown prep

Answer 29

1, No undercuts

2. Minimal taper
3. Well defined recordable margins
4. Adequate occlusal clearance
5. Adequate buccal/lingual/ approximate reduction
6. Clearance of contact point
7. Seating/ retention grooves on buccal of lower or palatal of upper
8. finishing of prep
9. no iatrogenic damage