Crowns and Laboratory stages Introduction Flashcards
Name some examples of crowns and give their associated acronyms
- Full veneer crowns (FVC)
- Metal ceramic crowns. (MCC)
- Porcelain jacket crown (PJC)
- All ceramic crowns (ACC)
What is a crown?
Restoration that is constructed outside the mouth and is designed to encompass the entire tooth
What is a crown preparations (prep)?
The original tithe that has been prepared fora crown to sit on top of it
What is taper?
The degree of convergence of the walls
What is height in regards to extra-coronal restorations
Distance from margin to occlusal/ incised surface of prep
What is the preparation margin?
A line that demarcates where the extra coronal restoration meets the remaining natural tooth tissue
Define retention
Refers to elements of the preparation that are preventing the crown from lifting up in a vertical direction
Define resistance
Refers to elements of the preparation that are preventing the crown from tipping or rotating off during function
What do we use to cement the crown onto the tooth
Luting cement
What can you do if there’s not enough tooth tissue remaining to achieve sufficient retention and resistance?
Can place a composite core to get the right height and taper
What do you have to consider if you are thinking placing a crown?
The biological cost
AS you remover more enamel and define you expose dentinal tubules which can act as a highway for bacteria straight to the pulp causing plural necrosis
What does the abbreviation FVC stand for
Full veneer crown
Give some advantages of a gold FVC
- Strong
- Similar hardness toenail
- Inert so don’t corrode in the mouth
- Minimal tooth reduction needs
- Single manufacturing process
Give some disadvantages of a golf FVC
- Aesthetics (depending on patient)
- Very expensive
- Inert so won’t bond to the tooth
Give some indications for a FVC
- To restore a tooth back to function
- Posterior teeth where aesthetics aren’t concerned
- teeth with limited starting height (less occlusal reduction needed than any other type of crown)
List the different steps involve for placing an FVC
- Crown prep
- Impression of crown prep
- Lab makes a model
- Die preparation
5, Start construction the crown using the lost wax technique - Metal crown is finished and polished
- Places on the patient using luting cement
What is the lost wax technique
It is where the crown is originally made from wax, the a mould is produced
This mould is heated causing the wax to get ‘lost’
The resulting space is filled with a molten alloy
What does MCC stand for?
Metal ceramic crown
give some advantages of placing a MCC
- Aesthetic
- Strong
- Durable
give some disadvantages of placing a MCC
Porcelain layer needs to be thick to hide metal underneath- this means more tooth is removed during prep
Give some indications for a MCC
- To restore a tooth back to function
2. used where aesthetics is a concern
Briefly talk tough how a MCC is made
- Wax pattern of metal substructure produced and sprued
- Metal substructure trimmed to fit desire die
- Porcelain is built up and given extra detail
- Cemented
What does PJC stand for?
Porcelain jacket crown
What is a PJC?
It is essentially a thin veneer of porcelain that wraps around the entirety of the tooth
When is a PJC usually placed?
If a patient has a pegged shaped incisor where theres low occlusal forces on the tooth and an aesthetic restoration is required
What are the disadvantages of a PJC?
Ha no metal substructure and porcelain on its own is brittle
What does ACC stand for?
All ceramic crown
What are the advantages of an ACC
- Good strength
2. Good aesthetics
How can ACCs be made?
Lost wax technique
OR
CAD/CAM in the surgery
How is an ACC made chair side in the surgery?
- Prepared tooth and the arch is scanned
- Design crown on computer software
- It is then milled
- The miles crowns polished then stained and glazed
