Restoration of the Endodontically Restored Tooth Flashcards
What are you looking for in a tooth that potentially needs to be endodontically treated?
- caries
- how much tooth structure is left
- able to be isolated?
- swelling/sinus
- ttp
- buccal sulcus tender to palpation?
- mobility
- increased pocketing
When assessing a radiograph of an endodontically restored tooth, what are you looking for?
- root filling voids/quality of obturation
- unfilled/missed canals
- patency (fractured instruments/posts/sclerosis)
- bone support
- crown to root ratio
- pathology
What are some problems of restoring RCT teeth?
- lack of remaining tooth structure
- fractured endo instruments
- perforations
What is coronal microleakage?
Ingress of micro-organisms into the root canal system
- important cause of RCT failure
What is the choice of restoration for a RCT anterior tooth with intact marginal ridges?
composite restoration veneer
What is the choice of restoration for a RCT anterior tooth with intact marginal ridges + discoloured crown?
bleaching or veneer (crown)
What is the choice of restoration for a RCT anterior tooth with destroyed marginal ridges?
- core build-up with crown
- post crown
what is a post/core?
- Core provides retention for crown
- Post retains the core
Do posts strengthen/reinforce teeth?
NO
- they simply retain the core
- preparation of root canal for a post weakens the tooth
Where is a post located?
Post placed in the root canal
What is a core? (RCT reference)
The core is what the prosthesis is cemented to
Should posts be placed in incisors or canines?
post unnecessary if sufficient coronal dentine is present
In which teeth should post placement be avoided?
Mandibular incisors due to thin/tapering/narrow mesiodistal roots
Why should you avoid placing a post in a curved canal?
Can cause perforation
What is the guideline root filling length for placement of a post?
4-5mm root filling apically
Why is coronal seal during RCT important?
good coronal seal will lead to healthier apical periodontal health as it prevents microbial leakage into the canals
What is the guidelines for post width in RCT teeth?
No more than 1/3rd of root width at narrowest point and 1mm of remaining circumferential coronal dentine
How much alveolar bone support is required for placement of a post?
At least half of post length into the root
what are examples of posts
Fiberglass
carbon fibre posts
What is the guidelines for post placement in terms of ferrule size?
at least 1.5mm height and width of remaining coronal dentine
What is a ferrule?
A dentine collar!
- encirclement of 1-2mm of vertical axial tooth structure within walls of a crown
- prevents tooth fracture
Crown margin has not been placed onto solid tooth, what is likely to occur?
root fracture significantly increased
What can be done to a tooth to achieve a ferrule before placement of a crown?
orthodontic extrusion or crown lengthening
What are the aspects of ‘the ideal post’?
- parallel sided
- non-threaded (passive, all posts are slightly threaded)
- cement retained
Why is it important that a post is parallel sided?
- avoids ‘wedging’
- more retentive than tapered
Why is it important that a post is non-threaded (passive)?
Smooth surface incorporates less stress to reminding tooth than threaded (active)
Why is it important that a post is cement retained?
Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/tooth
How can posts be manufactured?
- pre-formed
- prefabricated
- custom made
What materials can posts be made of?
- cast metal
- steel
- zirconia
- carbon/glass fibre
What shape can posts be?
parallel sided or tapered
What are the benefits of prefabricated posts?
- only 1 visit required
- no impressions and lab visit required
- immediate prep of core
- large selections of designs and materials
How are custom posts made?
- cast from direct pattern fabricated in patients mouth (duralay)
- 2 visits required = impressions and fit
What is the minimal standard restoration for a posterior endodontically treated tooth?
cuspal protection restoration (minimal standard restoration for a posterior endodontically treated tooth)
- prevent microbial ingress
- prevent catastrophic fracture (eg tooth splitting through furcation or buccal wall coming off tooth and taking cementum with it)
What is a core build up?
Internal part of tooth is built-up with restorative material to replace the lost tooth tissue
- can provide retention and resistance for permanent restorations
Where should you try not to place a post in the mouth?
Posterior tooth
- difficult access
- likely to cause perforation
What core materials are used?
- Composite = best option!
- Amalgam
- Glass ionomer
What is involved in placement of a Nayyar core?
- root treatment is removed from the root canals
- amalgam is packed into the root canals and tooth build up (provides retention for the amalgam)
- cannot be prepared for 24hrs until amalgam sets (PROBLEM)
- difficult process
What are the problems associated with posts?
- perforation
- core fracture
- root fracture or crack
- post fracture
How is a tooth managed that has had post perforation?
- repair = internal or external periradicular surgery
- extraction
What can be used to remove a post from a tooth?
- ultrasonics
- Masseran kit
- eggless
- miskito forceps
What are the reasons for post failure?
- 60% due to restorative reasons
- 32% due to periodontal problems
- 8% due to endodontic reasons
Do all cores need a post?
NO
What are the benefits and cons of using composite as a core material?
Benefits =
- tooth coloured (good aesthetics)
- bonds to tooth structure
Cons =
- technique sensitive
- moisture control required
What are the cons of using amalgam as a core material?
- poor aesthetics
- core cannot be prepped straight away as amalgam needs 24 hrs to set
What are the cons of using glas ionomer as a core material?
absorbs water so core expands in size
What should apply to the design of a core?
- 6º taper
- 10mm length
What would be included on the lab prescription for a post and core?
- please contrast cast post and core
- para post (colour)
- core 6º taper
- please leave 2mm space in occlusion for crown enclosed registration/opposing impression
What are the steps of a post try-in?
- check post space for temp bond
- irrigate chlorhexidine (0.2%)
- dry with paper points
- ensure fits around prep
- do you have enough occlusal clearance
What are the essential techniques of fitting a post-crown?
- be careful not to fill post space with cement
- use firm apical pressure
- get rid of excess
- make sure no excess around when taking crown impression/fitting MCC
What may be the signs of vertical root fracture?
- Long single pocket
- Repeated debonding of post/core
