What sort of retention features can be placed in vital teeth?
- Boxes
- Pins
- Grooves
- Bases
- Cores
How wide and deep must grooves be?
1.0mm wide and 1.0mm deep, and long as possible
Why are non-parallel pins placed in a tooth?
To retain a core buildup
How are pins placed?
- In sound dentin
- Not undermining enamel
- Avoiding perforations into PDL
- Doesn’t encroach on pulp
- Vertically in shoulders or ledges
- Surrounded by at least .5mm of dentin
Self threading pins are nearly _______ more retentive than cemented?
5 times
Threaded core pins are placed ______ deep, and cemented core pins are placed ______ deep.
- 2mm
- 4mm
What are cement bases used for?
- To protect pulp and eliminate undercuts in defects
- GI and polycarboxylate cements are excellent
- Can’t place retentive features in bases
When should a cusp be shortened?
All cusps thinner than half their height should be shortened
What core type can serve as a temp for weeks because of full contour restoration, and is best for subgingival, and is stronger?
Amalgam
What core type is easily molded, same day preps, greater microleakage and must extend below core build up?
Composite core
If pulp is questionable or any exposure, what must be completed first?
Endo therapy
When must you remove existing restorations before placing core buildups?
- Always remove all existing restorations
- Over one year old or did not place it
Placing retention, pins, grooves, and boxes in a base is the same as ________?
Not using them at all - retention and resistance forms must be placed into solid tooth structure
Why devitalize a tooth?
To obtain retention
Endodontic teeth are more prone to ______?
Fracture
The most important factor in fracture resistance is the _________ diameter of the tooth?
Buccal - lingual
Do all endodontically treated teeth need crowns?
No - anterior teeth
What are the incidence of failure percentages for the following:
- Single crown
- FPD abutment
- RPD abutment
- 5%
- 11%
- 23%
What is the main purpose of posts?
- To retain the core
- Does not reinforce tooth
What is the main disadvantage of composite cores?
Bonding to dentin is not that strong
What are the different post designs and their characteristics?
- Active - (best retention method)
- Threads to engage dentin
- Passive
- Smaller diameter than drill, no threads, bonded
- Hybrid
- Active at coronal and passive at apical
- Used where some mechanical retention is needed
What type of post provides the most retentive with the least amount of stress?
- A well-adapted, passively luted, parallel-sided post
What are the different post materials?
- Stainless steel
- Titanium
- Fiber reinforced
- Ceramic
How long should posts be?
- 2/3 length of root
