Dentures and Crowns/Bridges Flashcards
What modifications can be added to milled crowns in denture patients?
Plan denture design first, with surveyed casts and consider need for integrated:
- Rest seats- mesial and distal
- Guide planes- palatal/distal
- Buccal undercuts (0.25mm for clasp)
- Metal biting surfaces- for metal to metal contact with CoCr denture
When making a new crown/bridge alongside denture how is the master impression taken?
Take master impression of denture bearing area and for crown at same time
- Requires monophase or polyether material for enhanced accuracy
What are the steps in the try-in when a new crown and denture are being produced at the same time?
Try in with crown in place with temporary cement and denture seated
- When cementing crown definitely ensure it is seated properly and excess removed, then seat denture
- Prevents crown rising up from prep and denture not sitting correctly
What are the issues with tube lock precision attachments?
- Must be highly precise
- Huge torque on tooth especially with free end saddles (no stress breaker for flex)
- Patient may have difficulty cleaning
- Technically demanding
What are the different types of stud precision attachment?
Ball and socket- socket on denture that can connect with root treated tooth that has post with ball on it
-> needs height to allow ball to protrude
-> Good on canines, premolars (centrals in some cases)
In a zest anchor attachment- reversed (ball on denture with socket on tooth)
-> Fibre glass balls- that can be replaced easily (cold cured back into place)
How can survey lines be modified to become more favourable?
Design denture first
- Use composite or crown shape to creat undercut to allow clasp arm to engage it for retention
What are the ways of adding crowns to teeth when the patient already has a denture?
Need to be accurate around denture to prevent plaque trap
- All porcelain crown can be used- get back and try in at baked stage, trim it until it fits, send back and get it glazed (can be done with plastic mock up too)
- Take impression with denture in place- may require retraction cord (difficult to do)
- Build up using duralay acrylic- build up shape with chrome and take impression
*Go with technicians way
What are the steps in adding crowns to existing dentures? (duralay method)
Temporise the tooth- carve it to fit denture
Take impression without denture in before you prepare it
Replace temporary with core and prep tooth
Take master impression of crown prep
Using impression that you made of temporised tooth- duralay is put in to impression
-> this is reseated- check denture fits around (adjust if required)
Original impression used to make duralay is used to make temporary
-> Reseat temporary and fit denture
Send master imp, lower cast IO record and duralay to technician
Duralay is fitted to cast- wax up around gingival Margin to check fit
-> crown is casted in metal
New crown is identical in shape to temporary filling
-> carry out minor adjustments
-> cement crown and check with denture
What modifications may be made to crowns when contingency planning for future dentures in required?
Design crowns with future dentures in mind
Tunnel preparation- enables cleaning through furcation
Consider where you want clasps (put it in hidden position) on rest seats in future
-> this will increase the chance of the crowned tooth being a good abutment in the future
How can one tooth anterior saddle that keeps fracturing be fixed?
Replace anterior saddle with cantilever bridge (can be adhesive)
-> simplifies design
What can be done to avoid dentures?
Use of bridges and implants
Acceptance of spaces
-> if gap awkward size
-> if adjacent teeth are tilted
What are the advantages of fixed-fixed adhesive bridges?
Pink porcelain can be added below pontics
-> dependent on where the join is to make it look more natural
If periodontal disease- splint teeth
What is the one of the most common reasons for combining crowns and bridges with dentures, what is often an issue with this?
Tooth wear rehabilitations
-> patient may not have worn dentures and may require transitional dentures
What must we ensure with transitional dentures?
That they stay in- difficult as acrylic partials are usually poor, so add Adam’s clasps (aim for patient to have good experience)
What happens if the patient can cope with transitional dentures?
Consider definitive treatment
-> design denture first then plan crowns around it (with relevant modifications to optimise denture retention)
