the core to success - crowns and conventional bridges Flashcards
(34 cards)
What is the core in dental restoration?
A restoration placed in teeth with minimal tooth structure left to anchor an indirect restoration such as a crown.
What are the materials of direct cores? 5
Amalgam, Composite, GI (Glass Ionomer), Resin modified glass ionomer, Compomer, Metal alloy.
What are the advantages of using amalgam as a direct core material? 5
- Not technique sensitive
- Strong
- Bonded amalgam
- Distinguishes between amalgam and tooth
- Packable
What are the disadvantages of using amalgam as a direct core material? 7
- Setting time 24hrs
- Low initial strength
- Weak if thin
- Contains mercury
- Contraindications: pregnancy/breastfeeding
- Can react with other metals in crowns
- Not adhesive
What are the advantages of using composite as a direct core material? 6
- Strong even in thin sections
- Immediate setting
- Can be bonded to tooth
- Doesn’t contain mercury
- Tooth coloured
- Good coronal seal
What are the disadvantages of using composite as a direct core material? 4
- Technique sensitive (moisture and shrinkage)
- Expansion in water (die relief)
- Difficult to distinguish from tooth
- Plastic
What are the advantages of using GI and resin modified glass ionomer as a direct core material? 4
- Quick set
- Adhesive
- Fluoride release
- Low thermal expansion
What are the disadvantages of using GI and resin modified glass ionomer as a direct core material? 4
- Not strong
- Deteriorates at low pH
- Moisture sensitive
- Not packable
if there is no ferrule is a crown possible?
If there is no ferrule, there is not enough tooth structure, and a crown is not possible.
What are two methods of retention for amalgam in vital teeth?
- Undercut preparation
- Adhesive materials - amalgam bonding
What steps are involved in amalgam bonding? 10
- Cavity prep
- Lining if deep
- Etch
- Rinse
- Dry
- Isolation
- Dentine bonding agent on whole cavity
- Light cure
- Adhesive resin cement on base and walls
- Pack amalgam and wipe away excess cement
name 2 dentine bonding agents are used in amalgam bonding?
panavia A&B
Scotch bond
name 2 adhesive resin cements used in amalgam bonding
Panavia, RelyX ARC
posts are usually only used in what kind of teeth?
single rooted teeth
what teeth are posts avoided in?
Avoided in posterior teeth due to diverging roots - perforation
remember
it is recommended to achieve good coronal seal as soon as possible after root canal treatment (RCT).
how are cores retained in endodontically treated teeth?
Remove gutta percha from pulp chamber place GI or resin modified GI over floor of pulp chamber and root canal openings
What is a Nayyar core?
A technique where gutta percha is removed, and flowable material is added into the chamber and canals, best suited for amalgam.
What are the disadvantages of posts in posterior teeth? 2
- Don’t reinforce roots
- Roots often narrow and curved leading to perforation, Weakened tooth and Risk of root fracture
posts only need to retain cores if what?
Only if the tooth is heavily broken down.
do metal posts reinforce roots?
no
when are posts not required?
if enough coronal tooth structure
what is the best material for coronal seat of posts?
composite
What is the recommended method for removing gutta percha for post placement?
- Soften with heat or chemicals
- Mechanical methods using blunt non-cutting tips -> gates glidden burs
