temporary crowns Flashcards
Can cement “fill in the gaps” of a bad crown prep?
Don’t rely on cement to fill in the gaps when making crowns because it is water soluble and will degrade over time leading to compromised structure afterwards.
What can temporary crown tell us?
It can provide us with information about adequacy of retention and resistance forms of the crown.
Fit of the provisional restoration can be understood and this can provide us with information about the final crown
What can temporary crown tell us?
It can provide us with information about adequacy of retention and resistance forms of the crown.
Fit of the provisional restoration can be understood and this can provide us with information about the final crown
What is the problem of using zirconium crowns?
You cannot bond zirconium to the tooth almost purely mechanical bonding
How are materials selected for in prosthesis that is used?
Material choice depends on the anticipated load
Prosthesis design
Span length
Duration of provisional restoration
What are the materials used for temporary prosthesis?
Polymethyl methacrylate
Polyethyl methacrylate
Bisacryl composite resin
Light-cured composite resin
What are the pros and cons of using PMMA?
Very strong and lasts long
Has good colour stability
Can be characterized
Easily smoothed and polished
Low cost
Cons:
Highly exothermic can be traumatic to the pulp
Significant polymerization shrinkage
Monomer release
Unpleasant odour
What are the indications of using PMMA?
Should not be used directly in the mouth
Lab construction indirectly restoration
Shell construction in lab
What are the pros and cons of PEMA?
Pros:
Less exothermic than PMMA
Moderate strength
Can be smoothed and polished
Can be characterized
Easily repaired
Low cost
Cons:
What are the indications for PEMA?
Single crowns
Short span bridge
Short term provisional restoration
Relining pre formed or laboratory made shell
What are the pros and cons of bisacryl composite resin?
Pros:
Low exothermic reaction
Minimal polymeriation shrinkage
Ease of application
Can be smoothed and polished
Can be characterized
Cons:
Brittle
Difficult to repair
Does not bond to polycarbonate crowns
High cost
How are temporary crowns made?
Direct:
Chairside using prefabricated mold or customized
Indirect:
Why aren’t acetate strip crowns used at OHCWA?
Acetate strip crowns are hard to remove once they are on and are very difficult to work with
What are the types of fabrication techniques and what do they entail?
Indirect:
Stone model is conservatively prepared in the lab (supragingival margins)
Provisional restoration is constructed in the lab with aid of template.
Direct:
Provisional restoration is tried in the mouth and adjusted accordingly
