Midterm Flashcards
(57 cards)
What kind of bonding chemical bonding occurs between porcelain and zirconia?
None
Porcelain does however form chemical bonds with metals via the metal oxide layer
What kind of functional group is used in bonding chemistry for most dentistry?
Ester chemistry
What is the “mon” of all the “mer”s?
Methacrylate unit
___ monomers connects the polymer to something different.
___ monomers, like bis-gma is what forms the polymer
Functional monomers
Cross-linking monomers
In functional monomers one end is the methacrylate unit and the other performs a specific function (which joins organic to the inorganic). What does phosphate group bind to? What does silane bond to?
Metallic oxides
Glassy ceramics
The ____ group is the basis for acidic monomers and self-etch adhesives
Phosphate
MDP is an ____. It bonds to ___
Acidic monomer
Zirconia
Two viscous cross linking monomers are ___ and ___. A cross-linking monomer to reduce viscosity is ____
Bis-GMA
UDMA
TEGDMA
What causes initiation in a self initiating monomer?
Tertiary amine in a base paste
BPO chemical initiation in a catalyst paste
Combination of the two pastes produces free radicals that attack the carbon double bonds
What are found in photo initiated monomers?
Camphorquinone or other photo-initiator absorbs blue light, then reacts with amine activator to form free radicals
These free radicals then attack carbon double bonds
Inhibitors such as ___ and ___ are found in the catalyst paste of self-cure resins to prevent spontaneous polymerization and provide working time
BHT
MEHQ
(Oxygen is also a powerful inhibitor as it reacts with the radicals to form peroxyl formulations)
The tertiary amine eliminates the need for ___ to initiate free radical formation in self cure resins
Heat
Where does the free radical come from in self cure resins?
BPO
What are some other photoinitiators that are like camphorquinone?
Sulfinic acids
What kind of cure are adhesive cements, self adhesive cements, and esthetic cements?
Adhesive = self cure
Self adhesive = dual cure
Esthetic resin cement = either self or dual cure
True or false.. base paste can be used alone in a dual cure composite
True
Base paste can be used alone in light-cure mode or mixed with catalyst paste for dual cure mode
Incompatibility between bonding agents and dual cure composite resin formulations primarily occurs with ____ due to ____
Self etch adhesives
Acidic monomers
Can also occur with two-step etch and rinse adhesives when acidic amonomers are present in the un-polymerized oxygen inhibited layer
This can cause a problem with build-ups
The mechanism of failure of self etch adhesives and dual cure composite resin is due to two things which are…
- Neutralization of the tertiary amine co-initiators by acidic monomers (pH <3)
- H2O contamination of the adhesive/composite interface
Describe the H2O contamination mechanism of bonding agents with dual cure composites
During the time it takes for a complete cure in the deeper layers of the material, moisture from the dentin is osmotically pulled across the semi-permeable adhesive layer and into the uncurled composite resin at the interface.
How long should you acid etch for lithium disilicate, leucite ceramic, felspathic ceramic, and zirconia?
Lithium disilicate - 20s with 5% HF
Leucite ceramic - 60s with 5% HF
Feldspathic ceramic - 120 s with 9% HF
Zirconia - do not etch! Sand blast intaglio surface (AKA microetch)
Silane comes in two forms: ___ and ___ (acid activated)
Pre-hydrolyzed
Hydrolyzed
Silane bonds to ___
Glassy ceramics (AKA vitreous ceramics)
When should you bond zirconia?
Resistance and retention form in inadequate
Restorative material is thin
The restoration is a FPD
Do not allow the indirect restoration to be disturbed during clean-up for full time of resin cement set. The only exception to theis is with ___
Adhesive resin cements
