May 26, 2016 Flashcards
What tray(s) do we use for taking the definiive impression?
custom fabricated tray or stock tray
We use this technique when making direct interim restorations:
ESF
3 techniques for making interim restorations:
direct, indirect, indirect-direct
indirect technique:
Make interim from impression in lab from cast, prep the cast as conservatively as possible (so we are making a temp based off of a different prep? conservative so we know we will have a little extra space that can be filled with PMMA through the whole
Indirect-direct technique:
Fabricate shell before preparation of the tooth out of PMMA using the diagnostic cast, line shell intraorally
Materials for direct restorations:
PMMA, autopolymerizing acrylic resin, others ( polycarbonate), autocured composite resin, bisacrylate,
Functions of interim
esthetics, establishes function, diagnostic tool to see if tx plann is effective for patient
Issue with improper restoration:
inflammed soft tissue, overgrowth over finish line, taking definitive impression not possible due to inflammation and bleeding
Liquid to powder ratio for PMMA:
3:1
PMMA
Plymethyl MethAcrylate PMMA
What type of reaction is taking place with PMMA?
addition polymerization
stages of PMMA polymerization:
sandy, stringy, doughy, rubbery, stiff
TF Monomer is highly volatile.
T
Composition of powder:
polymer (methyl methacrylate) , initiator (benzoyl peroxide), plasticizer, opacifier, and pigments
polymer for the material we are using:
mehyl methacrylates (beads or pearls)
initiator:
benzoyl peroxide
Pigments:
to give the required shades
Fxn of plasticizer:
alters the physical properties
TF? Heat is taken in during the process of polymerization.
F. given off, free radical creation, exothermic
Bisacrylate vs. PMMA:
Autocured composite resin: no taste/odor, virtually no shrinkage, very good fit, color stable, shorter setting time, good esthetics, stiffness (prone to chipping, esp with undercut)) higher cost, good strength, good wear resistance
TF We will have significant undercuts below the finish line.
T. Block with inlay wax
Types of direct technique materials
bisacrylate or PMMA (use PMMA this semester), ESP-clear matrix or ESF-Silicon, PMMA - easier to reline, less prone to fracture
Temp of bath water
120 degress
After applying wax below the finish line and in surrounding crevices:
apply lubricant to the prep and adjacent teeth, mix ortho resin and jet acrylic, 1:1
TF Add powder to liquid when mixing the jet acrylic.
F. liquid to powder, drippy consistency
To what surface should we apply lubricant on the ESF-Clear matrix?
intalgio surface
Is lubricant needed with ESF-silicon?
no
During what stage should the mix be placed in the matix?
stringy stage
How to move the mix back into the prepared tooth area of the ESF-Silicon when it leaks into adjacent teeth:
mixing spatula
TF PMMA sticks to clear matrix.
T, this is why we apply lubricant
Purpose of adding the ESF-mix to the hot bath water for a FEW SECONDS:
to speed setting time and minimize amount of monomer
Where should you apply pressure when placing the ESF matrix on the prepared tooth area?
pressure on the djacent teeth, not the prepared tooth
Setting time for ESF-mix:
2-3 miniutes, lift ESF, but do not remove, replace ESF
Purpose of removing and replacing the interim while it is setting
to not lock in undercuts, both she’ll and interim are removed
To remove PMMA if if doesn’t come out with matrix
hemostat
Mark these protions of the interim restoration
Finish line and contact area
Where should you cut to remove the large excess?
from the side of the margin (with cone shaped e-cutter)