Provisional Materials Flashcards
What are the three most common provisional methods
direct
PVS impression or clear stent
integrity or tempbond
What are the three categories of failure of a provisional
re-cemented
re-contoured
remade
What is the failure rate of provisionals in dental school (UNC)
18.75%
What was the median time for failure of provisionals
12 days
What are five risk factors that could increase the risk of a molar provisional failing
isolation clinical crown height occlusal forces lateral interferences reuse of existing provisional at the time of the finalized prep
What are eight properties of an ideal interim material
convenient handling; adequate working time, easy molding, rapid setting time biocompatible dimensionally stable ease of contouring/polishing adequate strength/abrasion resistance good appearance patient acceptability ease of adding/repairing chemical compatibility with luting agents
What type of material are the acrylics
plastics
What type of material are the BisAcryls
composites
Which material are the dimethacrylates
bisAcryls
Which material are the monomethacrylates
acrylics
What are the two types of acrylics
polymethyl methacrylate
polyethyl methacrylate
What are the two types of BisAcryls
BisGMA based (most common) Urethane dimethacrylate base
Which one, Jet or Trim, is a polymethyl methacrylate
Jet
Trim is a polyethyl methacrylate
Which material is tough, but soft, and melt
monomethacrylates
Which material is brittle, hard, and will burn
dimethacrylate; composites
What are the four stages of free radical polymerization
activation (light, mixing, etc.)
initiation
propagation
termination
What is the change in density from a liquid monomer to a solid polymer
the density increases
low density → high density
The change in density is realized through what
shrinkage
Once the polymerization reaction starts, it can be what
be very fast and generate lots of heat
How can you reduce shrinkage
add fillers; PMMA, PEMA beads
What are the three components of monomer liquids
monomer
inhibitors
1/2 chemical initiators
What are the three components of the powder
polymer beads
colorants
1/2 chemical initiators
What is the purpose of the separate chemical initiators in the liquid and solid
This is why you cannot mix liquids from one system into powders of another
These are based on “composite” technology; higher molecular weight monomers “oligomers”
BisAcryl materials
Bis Acryl materials have reduced what
shrinkage
This filler is used to control fillers
silicate glasses
What are two properties of silicate glasses making it a good filer
strengthen
optical properties
What are four disadvantages of BisAcryls
limited shades
expensive
brittle
alteration and repair difficult
