ENDO - Restoration Options for Root-Filled Teeth Flashcards
what is generally the two options of a patient with pulpal disease?
extract
RCT
what if you want to do a RCT, but there is insufficient tooth tissue for strength or to create a ferrule?
extract and can put an over denture abutment on it
what is a ferrule? what is it used for?
part of the crown that goes around the remaining dentine
- helps to retain a tooth root against forces
define the ferrule effect.
cementing a ferrule or 360º metal around a tooth, preventing independent flexure of tooth structures
what is the role of a ferrule?
- to bind to the remaining tooth
- prevent root fracture
- provide resistance from the crown dislodging in function
what should be the height and width of the ferrule?
2mm x 1mm
which tooth is a ferrule most effective?
upper incisor as it supports occlusive forces
what happens if you put a crown on a badly worn down tooth and have no ferrule?
it will not support the occlusive forces
- leads to root fractures
What are the 3 Basic Areas to Assess of Root Filled Teeth Requiring Endo?
Endodontic Assessment
Periodontal Assessment
Coronal Tissue Assessment
what comes under coronal tissue assessment?
- remove any existing restorations and decay
- evaluate remaining tooth tissue
- thickness
- all positions of tissue
- min height for ferrule - aesthetics
- discolouration and shape - occlusion
- lateral or protrusive guidance
- how large are forces during function
What are the 4 Principles of Restoring Root Filled Teeth?
- provide a coronal biological seal to prevent re-infection of the root canal system
- protect remaining tooth structure
- maintain occlusal stability and proximal contact to prevent over eruption or drifting
- restore function
what do you use to restore the tooth with sufficient tooth tissue?
amalgam or composite with a RMGIC base to seal
what do you use to restore the tooth with great tooth loss but yet a ferrule is still possible.
a direct amalgam or composite core
- then prepare for crown or onlay
As though a root canal is harder and harder to fill, what techniques are used?
- composite
- composite Nayyar type core
- prefabricated post
- cast post and core
What is a Nayyer Type Core? How is it done?
relies on shape of root canal for retention
- doesn’t need a post
do procedure as normal up to obturation
- use gates-glidden drill
- remove 2-4mm of GP
- place thin layer or RMGIC
- condense amalgam or composite into root canals
- finish
Why may you need posts in RCT? What is one large disadvantage..
- retain the core
but can weaken the teeth and cause perforations
2 Types of Posts.
prefabricated post
cast post and core
Describe a Pre-Fabricated Post and types.
it is done chair side
- a post channel is prepared in the tooth and post is immediately cemented
- stainless steel
- titanium
- fibre-reinforced composites = fibre posts
Describe the Technique in Installing a Pre-Fabricated Post.
- use gates-glidden bur to remove GP
- use parapost drills - prepare post channel
- see if fibre post matches length and stability
Give 6 Advantages to Fibre Posts
aesthetic
metal free
bonds with resin and composite
flexural properties similar to dentine
can be removed
post is more likely to fracture than the root
Describe the Cast Post and Installation
- involves a lab stage
- post channel is prepared
- plastic impression post w/ silicone
- records shape of post shape
- post is cast with the core in the lab
- cemented into the tooth at a further visit
- temp post and core is needed between appointments
How long should a post be?
4-5mm apical GP should remain
- as much post as possible in the root which can be supported
What would be a Ideal Situation for stress distribution for a post?
- force transmitted to core and post
- transmits to dentine
- transmits to PDL and bone
What would be a Poor Situation for stress distribution for a post?
- force transmits to core and post
- transmits to dentine
- unsupported by PDL and bone
What should be the diameter for a post?
- narrower = preserve more tooth structure and reduce risk of root fracture
- too narrow = post may bend or fracture
4 Advantages of Pre-fabricated Post
- immediate coronal seal
- done at the same visit
- better aesthetics
- less stages = less discrepancies
1 Disadvantage of a Pre-Fabricated Post.
the core takes time to build
2 Advantages of a Cast Post and Core
- can go subgingivally
- good if the canal is oval
3 Disadvantages of a Cast Post and Core
- extra visits
- greater chance of discrepancies - impressions etc
- temporary seal difficulties
Which Teeth are at Greater Risk of Fracture?
posterior
how can a tooth be protected from fracture?
cuspal protection or full coverage restoration
e.g. extra-coronal restorations, inlays, onlays, full coverage crowns
In terms of Occlusion, what are the Guidelines for Post Crowns for Anterior, Posterior and Canines?
Anterior
- incised guidance should be shared across all ant
Posterior
- ICP contact point only
Canines
- should not provide canine guidance, should be group function
How can the Restoration of a Root Filled Tooth Fail? (4)
- Perforation
- Poor Coronal Seal - reinfection
- Root Fracture
- Fractured Post
