Flashcards in Dental Materials Part II, Test I Deck (64):
Class I cavities include what?
(5 points here)
All pit and fissure cavities
Occlusal 2/3 of Facial/LIngual surfaces
LIngual Max Incisors
Define Class II cavities
Class III cavities:
Do NOT involve incisal angle
Class IV cavities:
Involve Incisal angle
Class V cavities:
*non pit/fissure cavities
Class VI cavities:
Incisal edge Anterior teeth
Occlusal cusp heights Posterior teeth
In enamel bonding, what 2 structures are identifiable after etching with phosphoric acid gel?
What are the 3 procedures of Dentin Bonding?
What % of Dentin is water?
What are 4 functions of Etching in Dentin Bonding?
(removes 2 things, exposes 2 things)
Removes the smear layer
Removes HA from outer dentin layer
Exposes a collagen sponge layer
Exposes dentin tubules
During the Etching process, what must be done to keep the collagen sponge layer from collapsing?
In Dentin Bonding, the resin component part of the primer's attachment to the dentin is called what?
Hybrid Layer Formation
4 principles of adhesion in Dentin Bonding:
Hybrid Layer variable thickness
Mechanically weak if incomplete adherence with primer
Primer Solvents enhance wetting (monomers > tags)
To get monomers deep, many primer layers may be needed (as solvent evaporates)
What are the 2 parts of Primer that make it a Bifunctional Monomer?
What is an example of a Bifunctional monomer?
The self-etch two-step process has combined what?
Conditioner and Primer
Most bonding is a result of ________ retention
Currently the best bonding takes place on a _____ surface and agents containing ______ and ______.
MDP and Ethanol
What are the 4 Major Components of Resin Composite restorative material?
Organic polymer matrix
Inorganic filler particles
The Organic Polymer Matrix that make up resin composite are made up of what?
What are 3 examples of Oligomers?
What is the most common photoinitiator in Visible-Light Activation?
What wavelength does it absorb?
Blue light (400-500 nm)
*reacts w/ activator, forms free radicals, polymerization
The surface layer of resin composite's exposure to air may inhibit double bonds
What percentage of resin composite may be unreacted double bonds at the air contact surface layer?
What is present in bond failure interface in resin composite?
In resin composite, what is Polymerization Shrinkage a direct function of?
Volume Fraction of Polymer
Because Microfilled composite has a higher volume percentage of polymer, there is more/less shrinkage?
Why does Microhybrid composite have less shrinkage?
Less polymer matrix
Thermally speaking, why does Microfilled resin composite have More Expansion?
More polymer present
Compared to highly filled Fine Particle Composites, what is the E value of Microfilled composites?
1/4 to 1/2 E value
*microfilled not as good as highly filled fine particle
How is Irradiance (radiate exitance) measured?
# photos per second per unit area
How is Energy Density measured?
Irradiance x time
What is the most common photo-absorbing material?
What is the maximum spectrum sensitivity of Camphorquinone?
What are 5 factors that determine how long it takes to adequately cure a composite?
Energy Density (irradiance of light x time)
Distance from composite
Collimation of light (focusing/narrowing)
Wavelengths emitted and absorbed
What is the Reciprocity principle in terms of Total Energy Density?
Increase irradiance, Decrease time
Decrease irradiance, Increase time
What 2 types of light will lower irradiance and therefore increase curing time?
What type of light will increase irradiance and therefore decrease curing time?
Other than lowering Irradiance, name 5 factors that will Increase curing time
Other than increasing irradiance with plasma arc, name 4 factors that will Decrease curing time
What instrument part fits into the handpiece and provides the rotary motion to the bur?
What connects the head to the shank?
What is the working part of the instrument?
How are Rotary Cutting Instruments classified?
Number (which I think is size)
If the rake face is ahead of the radius, the bur has a ....
A negative rake angle is used for cutting hard brittle materials because it...
Minimizes fracture of the cutting edge
Increasing the Clearance Angle ________
Decreases the Edge Angle
What provides space for the chips formed ahead of the following blade?
Why are Carbide burs at around 90 degrees and need more of a rake angle?
This angle is considered?
Carbide is brittle
Clearance angles are either curved or have 2 surfaces to provide low clearance angles and greater clearance space ahead of the following blade.
What does a Coupling Agent ensure?
Bond forms between Inorganic filler and Oligomer during setting
What is an example of a Coupling Agent?
Coupling Agent like Silane is applied to the surface of the filler before it is mixed with Oligomer
When the Oligomer sets, the double bonds from the Silane react with the Oligomer to bridge a link between what?
Filler > Coupling Agent > Oligomer > polymer matrix
Compared to a Microhybrid, a Microfil will have more Matrix Resin in it. What are 5 consequences for Microfil?
Take up more water
More soluble in mouth
More polymerization shrinkage
Higher rate of Thermal Expansion
Lower Elastic Modulus
***overall, decreased properties
Where would Microfils most likely be used?
Where would Microhybrids most likely be used?
*one Doesn't go into heavy load-bearing areas
***Microfils shouldn't be used on load bearing interface - will stress tooth-composite bond because of "squishyness"
Round burs are measured from ____ to _____
Pear shaped bur common measurement:
Tapered fissure burs common measurement:
1/4 to 8
330, 329 (230-232)
What happens to the edge angle if you increase the clearance angle?
Edge angle decreases
What happens when we etch dentin?
What happens when we etch enamel?
Prevent drying, hybrid layer, collagen
What are the 4 components common to all bonding?
How is the Hybrid layer formed?
Resin in Primer > Etched Dentin
Look at HEMA molecule
Polymerization of composites:
Initiation, Propagation, Termination