Restoration of endodontically treated tooth Flashcards
How do we clinically assess an endodontically treated tooth
- assess coronal seal
- assess remaining tooth structure
- is the tooth restorable and can it be isolated
- swelling
- sinus
- TTP
- tender to palpation at apice
- mobility
- increased pocketing - perio disease/root fractures
How do we radiographically assess a root treatment
- root filling, length, quality
- unfilled/missed root canals
- patency - instrument fracture, post, sclerosis
- bone support - mild, moderate, severe
- crown to root ratio 1:1.5
- pathology
inadequate root fillings should be re-treated prior to restoration
What are problems after root canal treatment
- structural integrity lost both internally and externally
- lack of / no ferrule
- wide post holes (re-rct)
- endodontic complications e.g fractured instruments, perfs etc
If a root filled tooth has bene unrestored, after how long should you consider re-RCT
> 3 months
If root tx teeth are unrestored for <3 months, what can you do
- trim the gp
- place RMGI over pulp floor and root canal openings
- linings should not be too thick to allow for the remainder of the pulp chamber for retention and restoration
How can you restore anterior teeth with intact marginal ridges (access cavity only)
- composite or veneer
How do you restore anterior teeth with intact margin ridges and discoloured crown
- bleaching
- veneer
- crown
How do you restore anterior teeth with marginal ridges destroyed
core build up with crown
post crown
What are direct posts made of
fibre posts usually
What do fibreposts/direct posts require
ferrule
If there is no ferrule, what type of post is required
- cast post and core
What is the function of a post and core
gains intraradicular support for definitive restoration
What is the function of the core
provides retention for the crown
What is the function of a post
retains the core
Do posts strengthen or weaken
weaken the tooth
prep for the post is damaging
What are the guidelines for post placement in incisiors and canines
post unnecessary if sufficient coronal dentine present
avoid in mandibular incisors
Why should we avoid posts in mandibular incisors
they have thin/tapering/narrow mesiodistal roots
What is the anatomy of premolars
small pulp chambers
tapering roots
thin in mesiodistal cross section and proximal invaginations
place post in widest canal and avoid in curved ones
How much root filling is required to be left to maintain apical seal
4-5mm
How wide should the post be
- no more than 1/3 of root width at narrowest point
- 1mm of remaining circumferential dentine
What should the length of the post be
minimum 1:1 post length:crown ratio
want sufficient alveolar bone support so half of the length should be into the root
What is a ferrule
a dentine collar
it is the encirclement of 1-2mm of vertical axial tooth structure within the walls of a crown
What is the function of a ferrule
prevents tooth fracture
How does a ferrule prevent tooth fracture
- the crown margins are braced on the neck of the tooth and resistance is provided
How may a ferrule be achieved if there isnt one present
ortho extrusion
crown lengthening
not v common
How much ferrule do we want
at least 1.5mm in height and width of remaining coronal dentine
What are the features of an ideal post
- parallel sided
- non-threaded (passive)
- cement reteained
What is the benefit of a parallel sided post
avoids weding
more retentive than tapered
less flexing on loading
What is the benefit of a non-threaded post
smooth surface incorporates less stress to remaining tooth than threaded
What is the benefit of a cement retained post
- less retentive than threaded
- acts as a buffer between masticatory forces and post/tooth
What are the benefits of a prefrabricated post
- only 1 visit required
- no impression and lab visits
chairside core build up - post and cores are different materials
- immediate preparation of core
- large selection of designs and materials
What are the post materials
- metal
- ceramics
- fibre
What metals are used for posts
- cast gold
- stainless steel
- brass
- titanium
What are the advantages of metal posts
- radiopaque
What are the disadvantages of metal posts
- poor aesthetics
- root fracture
- corrosion
- nickel sensitivity
What are the ceramic post materials
- alumina
- zirconia
What are the advantages of ceramic posts
high flexural strength
fracture toughness
favourable aesthetics
What are the disadvantages of ceramic posts
difficult retrievability
root fracture common
What are the different fibre posts material
glass
quartz
carbon
What are the advantages of fibre posts
- flexible
- similar properties to dentine
- aesthetic
- retrievable
- bond to dentine via DBA
What are the disadvantages of fibre posts
- radiolucent on xray
Here is a table of the adv vs disadv of differnet post types
What type of restoration do we restore posterior endodontically tx tooth with
- cuspal coverage
- usually massive loss in coronal fracture
What restorations provide cuspal coverage
onlay
crown
What does cuspal coverage prevent
coronal leakage
catostrophic fracture
How does cuspal coverage prevent fracture
during loading, forces directed downward
What is a core build up
internal part of tooth is built up with restorative material to replace lost tooth tissue
core is prepared
provides retention and resistance for definitive restorations
Should you use posts in posterior teeth
avoid
only long straight canals
high risk of perf
What are the 3 main core materials
- composite
- amalgam
- GI
What are the advantages of a composite core
- most commonly used
- tooth coloured so good aesthetics
- bonds to tooth structure
- used with fibre posts
What is the disadvantage of an amalgam core
- retention required
- poor aesthetics
- core cannot be prepared straight away
- need 24h to set
- avoid pinned amalgams
What is the disadvantage of GI core
- absorbs water
- core expands
What is a nayyar core
root tx is partially removed from root canals
material packed into root canals and tooth built up
traditionally done with amalgam as this provides retention for it
with amalgam, it cannot be prepared for 24h until it sets
Why is doing a nayyar core with composite risky
- if requires removal, can be hard to cut out the root canal as difficult to visualise
- increases risk of perf
What are the methods of post removal
- ultrasonic
- tephan
- eggler device
- moskito forceps (screw retained)
- sliding hammer
What are post removal problems
- root fracture
- render tooth unrestorable
- post space too wide
- break post
What are some risks with posts
- perf
- core fracture
- root fracture/crack
- post fracture
How do you manage a post perforation
XLA
repair (internal or external)
What is the main cause of post failure
restorative reasons
