Full veneer crowns Flashcards
List some indications for crowns
- To protect weakened teeth
- Restore tooth to function
- To improve/ restore aesthetics
- Can be used as abutments for fixed prosthesis,
Name the most suitable material for restoring dentition
Gold
Why is gold the most suitable material for restoring dentition
- Durable
- Strong in thin sections
- Does not wear the opposing tooth tissue
- Biocompatible
- Resistant to corrosion
- Easy to adjust and polish
What are some of the disadvantages of using golf to restore dentition
- Expensive
2. Unaesthetic for some people
List the principles of preparation
- Allow room for adequate thickness of metal
- Have retention and resistance form
- No undercuts
- Supragingival where possible
- Chamfered margins
- Be as conservative as possible
Name the stages of crown preparation
- Planar occlusal reduction
- Axial reduction
- Functional cusp bevel
- Seating groove (not essential)
What does planar occlusal reduction do
Provides structural durability
What does axial reduction do?
Provides retention and resistance
what does a functional cusp bevelling do?
Provides structural durability
What does a seating groove provide?
Retention and resistance but it is not essential
Name the different burs we may use when carrying out.a crown prep?
- Chamfer burr
- Fine needle point diamond
- Long tapered shoulder burr
- Ling pear shaped fissure burr
- Topedo
What is the chamfer bur made to do?
Used to give a round contour to the finish margins
What is the diameter of the chamfer burr?
1mm
What taper do we wish to achieve
A 0.5mm taper
What is the fine needle burr used to do?
It is very fine and used to break the contact points
What is a long tapered shoulder burr used to do?
On a metal ceramic preparation a labia shoulder is required and this has a flat base
A shoulder burr is used to create this
What is the taper of a shoulder burr?
6 degrees (the ideal taper for retention and resistance)
Whe is diamond fissure burr used?
When we want to use a shorter burr to reduce the occlusal surfaces with restricted access
What is another name for the torpedo burr?
Rugby ball diamond
What is the torpedo used to do?
Reduce the curve of the palatal aspect of incisors
List the stages of preparation
- Occlusal
- Buccal
- Lingual
- Mesial
- Distal
What are we aiming for when carrying our occlusal reduction for a gold crown
- 1mm occlusal clearance
2. Additional 0.5mm on the functional cusp
Name the functional cusps in the upper arch
Palatal cusps
Name the functional cusps in the lower arch
Buccal cusps
Which burr do we use for the occlusal reduction and why
Short fissure burr as it has a diameter of approx 1mm
Which burr do we use to reduce the functional cusp
chamfer burr
How mcc do we need to reduce the functional cusp?
1.5mm
How much axial reduction do we need to carry out?
MAX 0.5MM
List the criteria we use to send assess our crown prep
1, No undercuts
- Minimal taper
- Well defined recordable margins
- Adequate occlusal clearance
- Adequate buccal/lingual/ approximate reduction
- Clearance of contact point
- Seating/ retention grooves on buccal of lower or palatal of upper
- finishing of prep
- no iatrogenic damage
