Restoring an Endodontically treated tooth Flashcards
how do we clinically assess a RCT tooth? (8)
Has a coronal seal been achieved or is there leakage/secondary caries?
How much remaining tooth structure is there? - how much ferrule there is
Will the tooth be restorable?
Can you isolate the tooth with a clamp and rubber dam?
Is there swelling?
Is there a sinus present ?
Is the tooth TTP?
Is the tooth mobile?
how do we radiographically assess a RCT tooth? (8)
Does the filling reaching 1-2mm from the radiographic apex?
Are there voids in the filling material?
Is there material in
the crown - GP should terminate at the ACJ
Are there unfilled/missed canals?
Is the canal patent or is it sclerosed/ filled by fractured instrument?
Assess the bone support - mild, moderate or severe?
Assess the crown to root ratio - the root should be 1.5 times the length of the crown
Assess for pathology - periodical lesions/radiolucency, resorption and perforations.
what do you do if a RCT hasn’t been done under dental dam or you’re not sure?
retreat
what is microleakage?
Ingress of oral micro-organisms into the root canal system
what is best practice if a RCT has been unrestored and temporised for > 3 months?
retreat
how do we prevent coronal micorleakage?
trim the GP to the ACJ and seal over the orifice with RMGI
how do we restore RCT teeth? (2)
direct - composite
indirect - crown or post crown, veneer
what factor determines what restoration is placed on top of a RCT?
marginal ridges
what restoration do we place on top of a RCT tooth with intact marginal ridges?
direct composite
what restoration do we place on top of anterior RCT teeth with destroyed marginal ridges? (be specific) (2)
core build up crown (if ferrule is present)
post core crown
when are post crowns used?
when there is not enough dentine/ferrule present to retain a crown so have to gain intra-radicular support.
what are the procedural requirements when placing a post core crown? (3)
half of the post must extend into the root
4-5mm of GP below the post
1mm of circumferential dentine around the post
in what teeth/root anatomy do we avoid using posts? (2)
MANDIBULAR INCISORS
curved roots
what is ferrule? (2)
A dentine collar that is required to prevent tooth fracture and increase the longevity of the restoration
Ensures that the crown margins are on solid tooth i.e. dentine
what are the dentine measurements for adequate ferrule?
height = 1.5mm
width = 1.5mm
how do we classify posts? (3)
manufacture - prefabricated or custom
material - metal, ceramic, fibre
shape - tapered or parallel
what is the ideal post design and why? (3)
parallel sided - avoids wedging and increases retention
passive/non-threaded - lowers the risk of root fracture since the occlusal biting forces aren’t being transmitted down the root.
cement retained - cement acts as a buffer between the post/tooth and masticatory forces.
what are the advantages of non-threaded posts?
Smooth surface = No transmission of occlusal biting force within the root = less chance of fracture
(Posts with grooves are active therefore there is more force and more stress = greater chance of root fracture)
what are the advantages of parallel posts? (2)
Avoids wedging
More retentive
what are the advantages of cement retained posts? (1)
Cement acts as a buffer between masticatory forces and the post/tooth
what are the advantages of prefabricated posts? (4)
Only require 1 visit - less time consuming
No impressions needed
Immediate preparation/build up of the core at chair side
Large selection of materials
what are the disadvantages of custom posts? (2)
Require 2 visits
Tooth needs to be temporised between visits and there is a risk of contamination
what are the disadvantages of metal posts? (3)
Root fracture
Corrosion due to the hot and moist temperatures
Ni sensitivity
what are the advantages of metal posts?
Radiopaque on radiographs = easy to identify
what are the advantages of ceramic posts? (2)
High flexural strength
High toughness
what are the disadvantages of ceramic posts? (2)
the post doesn’t fracture but the root does as its not as tough/flexible as the post
Hard to retrieve
what are the advantages of fibre posts? (3)
Flexible: has similar properties to dentine
Aesthetically pleasing
Retrievable if needs to be removed
what are the disadvantages of fibre posts? (1)
Hard to identify on radiographs - looks similar to filling materials
what materials can be used as core build up (anterior and posterior) ? (1)
composite
X - Avoid amalgam and GI
why do we avoid the use of amalgam in core build ups? (2)
Retention is required alongside it
Can’t prepare straight away as the post takes at least 24 hours to set
why do we avoid the use of GI in core build ups?
Absorbs water and expands
Can’t get restoration fitted on top as it has expanded in size
what is a Nayyar core? (1)
Describe how we prepare (2)
Amalgam core in a posterior tooth
Pack the amalgam into some of the root canals and then built up into the pulp chamber
Prepare post > 24 hours after
what is required for a core build up?
ferrule
what POST CORE requires some ferrule? (1)
fibre post
Describe a ferrule preparation?
When you can place crown margins on solid tooth tissue and have 1.5mm (height and width) supra gingival dentine round the circumference of the tooth
Describe the Ferrule effect? (1)
What does this provide? (2)
Occurs when u place the crown margins on the ferrule
there is bracing in the coronal proportion of the tooth where the crown meets the ferrule prep
Provides;
Resistance to micro leakage and rotational forces
what PROVISIONAL restorations can we place before definitive post placement? (4)
Use a provisional and cement with temp bond - can be dislodges with mastcoatory forces
Immediate denture - problems with gingival haemorrhage
Dressings - poor aesthetic
Essex retainer
what is the risk associated with post crown removal?
root fracture
describe GP removal and provisional post placement. (10)
Can use dental dam but it can interfere with vision and has to be removed from the impression taking.
Must soften the GP using a heat source or solvent (eucalyptus)
Use the sequence of gates gladdens with irrigation between to remove Gp and widen.
Widen the canal to allow a gates glider size 3 into the straight section of the canal
Leave an apical plus go 3-5mm of GP
Use the first para post drill which corresponds to the size of GG 3 and then increase in size following the sequence and irrigating between
Try in the provisional para post
If too long you have to trim the apical end and it should be 2-3mm short of the incised edge of the adjacent tooth
Inject pro temp into the putty matrix and seat into the mouth
When the impression is removed ensure that the provisional (pro temp and the temporary post come out as one unit)
how long should you wait between provisional post placement and definitive post placement?
> 24 hours to allow the resin sealer to set
what tools can we use in post preparation?
Para post XP
how do we take a difinitive master impression for a post?(5)
Use a Light body putty wash around the prep;
Incorporate all of the margins and ensure the post is fully covered
Place putty impression over the top
Remove
The impression post should be embedded in the putty matrix
describe the outcomes of posts in posterior teeth?
poor outcomes
why do we avoid placing posts in posterior teeth? (1)
Higher risk of perforation from narrow and curved roots
what canals are utilised for post placement in posterior mandibular molars?
Distal canal
what canals are utilised for post placement in posterior maxillary molars?
palatal canal
why are cuspal protective restorations placed on top of RCT posterior teeth? (2)
To prevent a catastrophic fracture through the furcation (= unrestorable)
to maintain the coronal seal and prevent microbial ingress.
how many canals should we post in posterior teeth?
1
what problems are associated with post cores? (4)
perforation
core fracture
root fracture
post fracture
where are common sites of perforation of a post? (2)
Premolars
Buccal root canals
why do CORE fractures occur? (1)
when theres not enough tooth structure or ferrule
with what posts do root fractures commonly occur alongside?
ceramic
why do post fractures occur? (3)
Occurs if the post is;
too short
too narrow
subjected to a lot of lateral forces (clenching and grinding)
what instruments do we use for post removal? (6)
Ultra-sonics (used with masseran)
Trephan Masseran kits (used with ultrasonics)
Eggler device
Moskito forceps
Sliding hammer
anthogry
