SDEO Posts Flashcards
Consequences of endodontic tx tooth
Loss of proprioception - reduced by 30%
Function of a post
Fitted into prepped RC
Retains the core
You have a cavity with:
Minimal access cavity
4 intact walls
Do you require a post?
No
You have a cavity with:
Loss of 1 wall
MO/DO cavity
Do you require a post?
No
You have a cavity with:
Loss of 2 walls
MO/DO cavity
Do you require a post?
No
You have a cavity with:
Loss of 3 walls
Do you require a post?
Yes
You have a cavity with:
No walls remaining
Do you require a post?
Yes
Ideal ferrule mm
2-3mm
Minimum ferrule
1.5mm coronal dentine
Function of ferrule
Prevents root fracture
Name 3 forces that may cause root fractures
- Functional lever forces
- Lateral forces during post insertion
- Wedging effect of tapered posts
List the optimal post dimensions
1:1 crown: post ratio
Least 1/2 of post in root
1.5mm ferrule minimum
4-5mm GP present
No more than 3rd width at narrowest point
Placed in straight portion of canal
Name the different types of posts
Prefabricated (metal)
Custom made (direct or indirect)
Examples of post materials
SS
Titanium
Co/Cr
Gold
Ceramic (aluminia/zirconia)
Fibre (glass/carbon)
What are the features of an ideal post
Parallel (avoids wedging)
Non threaded (avoids stress)
Cement retained (buffer to dissipate masticatory forces)
Name 1 advantages and 1 disadvantage of a threaded post
ADV: increased retention
DISADV: stress –> root fracture
Advantages of a cast metal post
Reduced risk of perforation compared to parallel sided fibre post
Custom made: follow canal shape
Useful in flared canals
Disadvantages of a cast metal post
Impression required - lab + extra stages so more room for error + contamination
Advantages of a fibre post
Can be placed immediately
Low elastic modulus: dissipates stress over tooth
Tooth coloured
Compatible with current adhesive systems
Disadvantage of a fibre post + ceramic
Difficult to remove upon re-tx
Fibre = radiolucent on xray, Metal = radiopaque
Disadvantages of a metal post
Poor aesthetics
Root fracture
Corrosion
Common mode of failure for a cast and fibre post
CAST - root fracture
FIBRE - debond at post cement interface, recurrent caries
Compare the types of cement used for posts
Adhesive resin
- Greater retention + strength
- Premature setting –> incomplete seating
GI
- Easy to retrieve + F releasing
- Requires weeks to reach max strength
RMGI
- F releasing
- Absorbs water + expands
