Rest ops for root filled teeth Flashcards
What are the 2 main options when a patient has a tooth with pulpal disease
- Extract
- Consider endodontic treatment- pre-op assessment
What can be the outcomes of a pre-op assessment when considering endodontic treatment on a tooth
- insufficient tooth tissue for strength or to create ferrule
- sufficient tooth tissue for direct restoration
- greater tooth loss but ferrule possible
What are the options for a tooth that has insufficient tooth tissue for strength or to create ferrule
overdenture abutment
extract
What is an overdenture
a denture that goes on top of badly broken teeth
what is the ferrule of a tooth
what is its role
the portion of the crown that encircles the remaining dentine
binds to remaining tooth, prevents root from fracturing and provides resistance
pic
what should the height of the ferrule be
what should the width of the ferrule be
how much of an angle should the ferrule be encircling the tooth
atleast 2mm
atleast 1mm
360 degrees, but dependant on tooth as some surfaces are important than the other
what is the ferrule effect
during occlusion, the encircling of the crown on top of the sound dentine will transmit the forces in a more favourable way to the PDL and the bone, preventing fractures and dislodgement
What are the 3 sections of an assessment of a root filled tooth
endodontic assessment
periodontal assessment
coronal tissue assessment
Explain how to carry out a coronal tissue assessment
- remove existing restorations to evaluate remaining tooth tissue
- assess quality of remaining healthy tooth tissue
- height minimum 1.5-2mm for ferrule
- thickness of tooth tissue
- position of remaining healthy tooth tissue- B/L/M/D - aesthetics
- tooth/root discolouration
- tooth shape - occlusion
- is the tooth in occlusion
- does the tooth contribute to lateral or protrusive guidance
- will the forces on the tooth be low or high during function
what are the 4 rationale principles of restoring root filled teeth
- to provide a biological seal (coronal seal) to prevent infection of the root canal system
- to protect remaining tooth tissue
- to maintain occlusal stability and proximal contacts to prevent over eruption or drifting
- to restore function
What is the option for when a tooth has pulpal disease and sufficient tooth tissue for direct restoration
restore with composite (or amalgam) with weak cusps reduce and onlayed
What is the option for when a tooth has pulpal disease and greater tooth loss but a ferrule is possible
direct amalgam or composite core
then, preparation for indirect restoration (crown or onlay)
What do you require for a tooth with pulpal disease, has greater tooth loss but a ferrule is possible and the core requires additional retention and support
a post
what type of core is used when the tooth requires retention
a composite nayyar-type core
what type of post is used when the tooth requires more retention
prefabricated post
what type of post is used when the tooth requires most retention
cast post and core
to place a direct restoration, after you have finished your root canal tx, what must you do
remove gp until level with CEJ
seal gp inside the canal
what can be used to seal the gp in the canals
rmgic
describe the Nayyar type core (corono-radicular dowel)
doesn’t use a post
relies on the shape of the root canal to go in to different root canals and gain retention (retention from coronal and radicular tooth tissue)
2-4mm GP removed from each canal using gates glidden
pic
what are the 2 main types of posts
prefabricated post (chair-side)
cast post and core (lab involved)
What is the only use of posts
to retain core
what are some issues with posts
weaken teeth
can cause perforations
what type of posts should you use
parallel, tapered, non metal, ready made/custom made post
what types of posts should you avoid and why
threaded posts as they induce stress on the canals and can lead to fractures
what length should the post be
post length at least equal to cornal length, whilst still keeping enough apical seal
what is important when doing a post
the presence of a ferrule of 1.5-2mm is more important in fracture resistance than the post design or type
what 3 materials can a prefabricated post be made from
stainless steel
titanium
fibre-reinforced composite ‘fibre posts’
explain how to fit a prefabricated post
- use GG burs in order to remove GP- follow canal direction to desired length
- use parapost drills to prepare post channel
- try in matching fibre posts, ensure stability and fit to desired length (may need to move up drill size be aware of canal/root width)
Advantages of fibre posts
- aesthetics- metal free
- bond with dual and self cure resin cements and composite core material - benefits of adhesive techniques
- flexural properties closer to those of dentine
- can be removed for revision of endodontic treatment
- claimed to reinforce tooth (evidence hasn’t confirmed)
- post more likely to fracture than root, decementation is commonest mode of failure but retrievable failures
how do you make a cast post
- post channel is prepared in the tooth
- then a plastic impression post is used along with silicone impression material to record the shape of the post space within the canal
- a post is cast along with the core in the lab
- this single unit is then cemented into the tooth at a further visit
for when a cast post is being made, what is needed between appts
a temporary post and core
What are the 3 guidelines for post length
- As much as post as possible in root which is supported in bone
- Post length in bone at least as much as that above the boney crest level
- 4-5mm apical GP remaining
What are the 2 guidelines for post stress distribution
- Force transmitted to core and onto post
- Force transmitted to dentine
What are the 3 criteria for the post diameter
- Retain as much coronal and radicular dentine as possible
- Narrower diameter posts preserve more tooth structure and reduce risk of root fracture
- Too narrow a post may bend or fracture
2 advantages of cast post and core
Can go subgingivally
Good if oval canal
3 disadvantages of cast post and core
- Extra clinical visit
- Greater likelihood of discrepancies introduced by impressions, casting models, casting metal
- Temporisation difficult coronal seal
4 advantages of prefabricated post
+ Immediate coronal seal
+ Crown prep can be done at same visit
+ Better aesthetics (fibre post)
+ Reduced number of stages therefore
reduce discrepancies
1 disadvantage of prefabricated post
- Core takes time to build
3 options for cuspal protection
- Extra-coronal Restorations
- Inlays/ Onlays
- Full coverage crowns
3 guidelines for occlusion
- Post-crowned canines should not provide canine guidance - planned change to group function needed
- Post-crowned posterior teeth - ICP contact only
- Post-crowned anterior teeth - incisal guidance should be shared across all anterior teeth
4 ways root filled teeth can fail
- Perforations
- Poor coronal seal- reinfection of the root canal and apical pathology
- Root fracture
- Fractured post
