5. Lab Considerations II Flashcards
Teeth that have recieved a crown within _ months after RCT are more likely to survive than if done later
4
T/F: Remargination die is a substitute for a working cast
F
Purpose of remargination die
If you have an impression but you’re unsure if it is good you can take a quad impression for a remargination die
What do you have to do if your case is rejected
- Correct the error
- Write down your response to indicate what corrections were done
- Resubmit case- Don’t submit a new lab authorization page
Other things to include in the lab submission to provide missing information
- Dx wax up
- Cast of provisional restoration (cross mounted)
- Custom incisal guide table
- Clinical photos
Custom incisal table is made using what
Dx casts and GC pattern resin
When can you take pictures of the lateral and protrusive contacts
- Before the prep
- With the provisional
Know what you can hand articulate, bite reg and record bases for mounting
ok
Causes for mounting errors are
- Inaccurate casts
- Using interocclusal record when not indicated
- Using interocclusal record incorrectly
When is the most accurate- handarticulation, bite registration, record bases
hand articulation
Issues with casts leading to their inaccuracy includes
- Positives on occlusal surfaces
- Distortion in impression
The decision to mount the working cast with hand articulation or interocclusal records is made when
After tooth is prepped
Hand articulation of casts indicated when
- Sufficient unprepped teeth to locate treatment position (tripod)
- Occluding surfaces are accurate
Bite registrations are more accurate on (prepped/unprepped) teeth
prepped
Interocclusal record indicated when
-Existing unprepped teeth are too few in number or are not in position to located the treatment position
Materials available to make an interocclusal record
- Plaster
- Wax
- ZOE pastes
- Polyether
- PVS
- Resin .
Clinical suggestions for fabriation of interocclusal record
- Rehearse with patient
- Dry teeth
- Use minimal material
- Confirm accurate closure of the teeth
- Trim record
- Confirm complete seating on the casts (no rebound)
- Securely fix the casts together for mounting
- Reconfirm accuracy on articulator
How should the interocclusal record be trimmed
- Leave cusp tips and incisal edges
- Interproximal fins need to be trimmed
Excess material to make the interocclusal record can lead to .
- can cause an eccentric closure
- Prevents confirmation of correct closure
- Trimming is an increased challenge
Thickness of a trimmed interocclusal record should be about
1-2 mm
if you need a record base to mount the casts how many record bases must you make before submitting a case
2 one for the Dx casts and 1 for working cast (one for the working cast must be made on the working cast
It is the (dentist’s/lab tech’s) responsibility to ensure accurate occlusal contacts
dentists
Considerations for making record bases
- Should be stable and fit passively
- Have to be made on the cast to be mounted
How can the stability of a record base be improved
impression reline
Describe the process for impression reline of a record base
-Acrylic base adapted to the CAST with PVS
Advantages of impression reline
- Provides more intimate fit
- Allows minor undercut engagement
- More stable platform
