Posts Flashcards
What is a post and its purpose
Foundation for indirect restoration
The main purpose of a post is to provide anchorage for a core upon which a restoration can be placed
Indications for posts
When the crown of a tooth has been damaged to the extent that a conventional restoration to restore it is not attainable
When the coronal portion of a root filled tooth has been lost
What are the different types of posts?
Metal (nickel/ chrome alloy)
Prefabricated post (stainless steel/titanium alloy/nickel-chrome)
Cast post (gold alloys)
NON-METAL
Fibre posts
What are the advantages of metal posts? Not on LO
Adaptability- can compensate for between the angulation of the root and the planned crown
Core retention- cast posts don’t have the potential for separation like a prefabricated post and its core
Strength- in comparison to the non-metal counterparts
What are the disadvantages of metal posts?
Root fracture- have a higher incidence of root fracture than non-metal
Aesthetics- when an all ceramic crown is to be used the metal post can alter the optical properties
Biocompatibility- Corrosion?
Preparation of metal posts?
During prep- need to retain as much coronal dentine as possible
The amount of remaining dentine is determined by caries present and also the required dimensions for a crown
The preparation must allow-
Provision of a ferrule
Increase post retention
Resist post rotation
What is the ferulle effect?
When the supra-marginal dentine of a root filled tooth is engaged by a crown, it may create a stronger tooth/restoration complex. This is termed the ferrule effect”
A ferrule is achieved by the parallel walls of the dentine extending coronal to the shoulder of the preparation
This is a protective effect, reducing the stresses within the tooth
What is the definition of ferulle
A ferrule is a band of metal (of the indirect restoration) which totally encircles the tooth, extending 1 to 2 mm onto sound tooth tissue to guard against longitudinal fracture.
What are the other considerations in radicular preparation?
The width of the post is important and should not be more than 30% of the width of the root-face, measured in a labial-palatal direction
If a post is too narrow, it will have insufficient strength for long term survival
While excessive width increases the risk of perforation and root fracture
Some lower anterior teeth are very slender and unsuitable for para-post technique
Considerations for preparation of post
Post length
Post shape
Surface characteristics
Post space preparation
Guarding against coronal micro leakage
What about the post length
Long posts are more retentive than short posts
Posts can be lengthened by extending as apically as possible and leaving as much coronal tissue as possible
No place for de coronating roof top preps
Leave 4-5mm apical GP to ensure apical seal
Post shape considerations
Parallel sided posts more retentive than tapered posts
Wedging effects of tapered posts leading to root fracture
if its is a wide, flared post but thin walls, this is more prone to fracture
Surface characteristics of metal posts
Dentine - elastic
Self-tapping threads set up stresses
Some are also tapered
Often leading to root fracture
Examples- Radix anchor, Dentatus, Kurer anchor -prefabricated posts
Post-space preparation - Minimising danger
Prepare the post space at the time of obturation
Most familiar with angulation, reference points
Rubber dam still on keeps bacteria out
Guarding against coronal micro leakage
A major cause of root treatment failure
Saliva and microorganisms- poorly adapted restorations, even and well condensed RFS
Leading to periapical reinfection
