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What is an amalgam
a metal alloy of which one of the elements is mercury
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What are metal alloys
metals that are a combination of several elements
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Mercury is the only _______ that is ______ at room temperature
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What are the contents in the capsule
A set amount of mercury with metal alloy powder
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The process that the amalgam is mixed is called
trituration or amalgamation
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Amalgams are frequently used in what kind of restorations
Class I, II, and VI
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Amalgam is much more ______ than composites
moisture tolerant
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Explain the process of condensing
Pushing the amalgam in layers into the prepped tooth
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Amalgam are never used in what class
III
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Build-up Procedure With Amalgam is also called
- core build up
- crown build up
- amalgam build up
- amalgam core
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When would we do a Build-up Procedure With Amalgam
When there isn't enough structure to build a crown on
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Explain the retrofill procedure
The gum tissue is peeled back and filling is placed directly in the roots
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What material is used in a retrofill
MTA (mineral trioxide aggregate)
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What was the original method for creating amalgam powders
shaving down silver coins
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What are the three methods currently being used in the creation of amalgam powders
- Lathe cut alloy
- Spherical alloy
- Admixed or blended alloy
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Describe the lathe cut alloy
ingot (portion) of AgSn (silver+tin) is cut on a lathe producing small, irregular particles
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Describe the spherical alloy
- ingot of AgSnCu (silver, tin + cooper) melted down and sprayed thru a nozzle creating very small, uniform spheres of alloy.
- Faster setting
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Describe the Admixed or blended alloy
mixture of lathe cut and spherical alloys
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Low cooper amalgam is also known as
Traditional or Convential
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What are the percentages of the low copper composition of the amalgam
- Silver 65%
- Tin 25% + Mercury
- Copper 6%
- Zinc 1%
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If the zinc content of the amalgam is less than 0.01%, it is called a
non-zinc amalgam
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If the zinc content of the amalgam is more than .01% it is called a
zinc-containing amalgam
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What does the silver portion of the amalgam do
increases strength and corrosion resistance and causes setting expansion
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What does the tin portion of the amalgam do
decreases strength and corrosion resistance and causes setting contraction
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What does the zinc portion of the amalgam do
increases life expectancy of restoration
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In low copper amalgams, copper functions much the same as
silver
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Explain the setting reaction for low cooper amalgam
Mercury attacks the low copper alloy particles and dissolves the outer surface releasing ions
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What are the three phases in the setting reaction of low cooper
- Gamma phase
- Gamma 1
- Gamma 2
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Which phase of the setting reaction of low cooper is the strongest
Gamma phase Ag3Sn
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Explain Gamma1 phase
Gamma1 less strength and brittle
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Explain Gamma 2 phase
- weak link’ of the mix
- Corrodes much faster and is subject to fracture
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What is the percentage of the composition of the New formula of amalgam
- Silver 46-60%
- Tin 27% + Mercury
- Copper 13-30%
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What does the added copper in the new formula of amalgam do
produces better restoration with less corrosion and less marginal breakdown
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Explain the setting reaction of the high copper amalgam
The tin ions react with the copper preventing the formation of Gamma2 resulting in stronger and longer lasting restoration
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What is the function of the particle type
changes the physical character (ability to pack/carve/the amount of force needed to pack).
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More Hg in mix does what
increases plasticity and set time
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Properly triturated ball is
plastic, shiny, and holds together
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Over mixing produces a
hotter, drier, sticky mass with short working time and a quicker set
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Initially as the amalgam is setting there is a
slight overall contraction of the mass
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The slight open margin of the amalgam fill with the products of _______ over time
corrosion
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Creep
dimensional change of a material under constant stress (forces of occlusion
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Quality of amalgam is reduced if placed in a ______ or ____ preparation
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________ are the most affected by moisture
Zinc –containing amalgams
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Some dentists use a _______ or _______on the dentin to seal the dentinal tubules
cavity varnish (copal resin) or amalgam bonding agent
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Most failures occur in _____
thin areas (less than 1.5 mm)
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What are some properties of gold foil
- Almost pure gold is condensed into the preparation
- Difficult, time consuming, expensive, hard on the pulp, patient, and practitioner
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