Tooth wear and Indirect Restorations Flashcards
When are fixed restorations possible in tooth wear cases?
If 50% of structure still present above gingival margin
- Can consider crown lengthening surgery if this is not available
What are the issues with tooth preparation in wear cases?
Lack of occluso-gingival height (occlusal surface to top of gingival margin)
-> Little room for retention and resistance form
Lack of occlusal and palatal space
Severely compromised teeth
What can be done to maximise retention and resistance when placing indirect restorations on worn teeth?
Materials
Grooves/Inlays- reduce radiation of rotation
Ferrule
Parallel preps
Margins & occluding surfaces
Cores
Electrosurgery
Surgical Crown lengthening
What materials can be used for indirect restorations in tooth wear cases?
Metal ceramic
-> metal on biting surfaces
-> porcelain on aesthetic areas (may only be some of the cusp)
How are grooves prepped?
Cut down long axis of the tooth
-> parallel with path of insertion and removal
-> tell technician you want metal fitting surface of crown to go into groove
How can adding an inlay style prep to your crown prep be beneficial?
Walls give retention
-> good if high aesthetic demand
Why is it important to check radiographs before cutting grooves and inlays?
To check for position of pulp
What is the issue with no ferrule?
It is unlikely that the tooth will be restorable with crowns
-> lack of resistance form
What can be used to help us assess restorability of teeth?
Dental Practicality Index
What are the positives of parallel preps?
Aids retention of crown in shortened teeth
What are the issues with parallel preps?
Technician has less space to develop aesthetics leading to opaque crowns
-> inform patient that aesthetic compromise is likely
What can be done of worn teeth have large sub gingival restorations?
- Put core material in to restore deep cavity
- Electrosurgery- remove gum to ensure accuracy of impression and create ferrule
- Palatal groove- may be a better position in relation to pulp
What are the advantages of metal palatal surfaces in anterior teeth?
Opposing arch bites on metal
Useful in erosion cases
Minimal prep required due to thin metal
What are the advantages of a curved prep for porcelain?
Prevents debonding and crack propagation
-> esp helpful in wear cases where there is increased load
How can reinforced composite be helpful when restoring near the gingival margin?
Autocured- so will set in these conditions
What is a Nayyar core?
Amalgam core where GP is removed from canals at the coronal part and packed with amalgam
Why are metal margins around the bottom of posterior teeth preferred?
Less is removed from tooth
Less chance of going close to pulp
When is surgical crown lengthening considered in tooth wear cases?
After every other option has been exhausted and adhesive dentistry had failed
How is crown lengthening achieved?
Remove bone around tooth to increase amount of tooth in mouth and OG height
-> Retract flap, remove bone and excess gum and suture gum more apically
(Co-pack can help healing)
How long does it take for gingival margin to stabilise following surgical crown lengthening?
3 months
What can be placed while the gingival margin is stabilising following SCL?
Temporary crowns to cover over exposed root cementum and prevent sensitivity
What can be added to crowns to make them look more natural?
Features of tooth wear
Why may a dentist choose to have metal extend from biting surface partially onto buccal surface?
Can ensure that heavy contact on lateral excursions is less likely to fracture porcelain
What are the ADV of sanitary pontics?
Easier cleaning
Robust shoulder joint- less chance of patient sectioning bridge
Narrower occlusal surface- avoids shear forces in lateral excursion
What are the advantages of intermediate bridges?
Can be used during healing process
Can help us assess tooth contacts and aesthetics
Why may patient with bruxism require one implant for each lost tooth?
To deal with the excess load (prevent bone loss and failure)
What can be done so you can take an impression for a longer term temporary bridge following an extraction?
Put gauze in extraction socket
-> Can take 3-6 months for socket to heal and bone resorption to occur- definitive bridge can be placed then
What are the issues with worn dentures in patients with tooth wear?
It can increase the force coming from opposing teeth as OVD is lost increasing FWS
How can an old worn denture be used to re-establish OVD when treating tooth wear?
Drill cone shaped holes and fill with composite to help re-establish posterior support on existing denture as temporary measure
-> Then re-establish OVD definitively by replacing denture
What must we inform tooth wear patients of before they undergo any treatment involving indirect restorations?
Failure rates are much higher
-> understand limitations, pick good cases and seek advice by referral if required
