Post and cores Flashcards
Replace missing tooth structure prior
to crown preparation
Core restorations
“No preparation should be extended farther
into the tooth than ___ mm at the cervical
line or down ___ mm from the central fossa.
1.5 mm
If ___% or more of the coronal tooth
structure remains, sufficient retention for a
single crown can be achieved by adding
retentive features to the preparation.
50%
Advantages
*Easy to manipulate
*Favorable mechanical
properties (high compressive
strength, wear resistance, and
dimensional stability)
*Corrosion products
*Acceptable for areas difficult to
isolate
*Relatively inexpensive
imitations
*Relatively slow setting
*Usually cannot be prepared at the same visit
*High copper spherical amalgam alloys (set 15 min)
*Corrosion
*May cause discoloration of tooth structure
*Do not adhere to tooth structure
*Require a certain thickness for strength
*Color
Amalgam
*Bond to tooth structure
(however the bond strength
to dentin is weak)
*Can be used in thickness
<1mm
*Rapid polymerization
* can be prepared the same visit
*Time efficient, economical
*Relatively easy to manipulate
Limitations
*Bond strength to dentin is
weak, require mechanical
retention
*Very susceptible to
moisture contamination
*Require good isolation, the
core margins must be
supragingival (2 mm tooth
structure to provide a
ferrule)
* Polymerization shrinkage (microleakage
Composite
Significantly inferior strength compared to
amalgam alloys or composite resins
*Water imbibition
*Recommended only for low stress bearing areas or
as block-out materials for undercuts
GI and Resin ionomer
What is the max number of pins that can be used on tooth?
4
How far from the axial wall should a pin be placed?
at least 0.5 mm
HOw far from DEJ should pins be placed/
0.5 mm to 1 mm in denin inside DEJ
How much ferrule is needed?
2 mm circumferentially
a post, usually made of metal
that is fitted into a prepared root
canal of a natural tooth. When
combined with an artificial crown or
core, it provides retention and
resistance for the restoration.
FUNCTION of a POST
➢Anchor the core material with a
stable post
➢Restore missing tooth structure
➢Reinforced the tooth-restoration
Dowel:
- Usually cast in Type III gold
- Are often tapered and ovoid in cross section (built-
in anti-rotation) - Rely mostly on the cement for retention
- Less than 10% of clinicians use them
-Are the only option when the
crown and post have different angulations
Custom Posts
➢ The diameter of the post should not be greater
than ____ of the tooth/root diameter.
1/3
Main advantage: better esthetics
Main difference from metal posts:
* Modulus of elasticity similar to dentin (however the modulus
decrease over time and more critically in the presence of
moisture)
Failures:
* Less root fractures than metal posts, fracture usually occurs in
the coronal part or the post itself or debonding of the post
occurs
* Failure rates in the literature range from 0% to as high as 32.2%
and most are because the post becomes debonded
Indication for use: only teeth that have several dentinal
walls remaining
Fiber reinforced posts
Good esthetics
*Very rigid (high modulus of elasticity)
*High rates of root fracture
Ceramic posts
