what is the most widely used material in restorative and corrective dentistry?
METAL-amalgam
amalgam has had a reduced usage by _____% in the last ____ years
40
15
t/f testing has not show amalgam to be safe or harmful to humans, it is still undergoing testing.
FALSE, testing shows amalgam is safe
some disadvantages of amalgam is the lack of _____ and the fear of ______ safety
estehetics
mercury
what are the 7 metals contained in amalgam (four big ones in "red")
SILVER
COPPER
TIN
MERCURY
zinc
palladium
indium
the addition of _____ in amalgam composition causes a reaction called ______
mercury
amalgamation
adding what metal to amalgam causes amalgamation?
mercury
what is the chemical reaction called that mercury causes in amalgam
amalgamation
how are amalgams classified?
shape of particles (irregular, admixed, spherical)
what are the composition of MODERN amalgam (5)
copper
silver
tin
mercury
zinc
what % of MODERN amalgam is copper?
10-30
what % of MODERN amalgam is silver
40-70
what % of MODERN amalgam is tin
12-30
what % of MODERN amalgam is mercury? and how is it measured?
43-50
by weight
t/f mercury is measured for modern amalgam by particle size
FALSE-by weight
what % of MODERN amalgam is zinc
.01-2
what are two advantages to shperical alloys?
less mercury
set faster
t/f spherical alloys set faster than lateh cut
true
t/f with spherical alloys more mercury is required to bring all materials together (amalgumation)
FALSE, less mercury required GOT IT!
zinc in amalgam inhibits _______ by reducing ______ of other metals
corrosion
oxidation
in _____ copper amalgam, when moisture is present during placement, the zinc is responsible for gradual _____ of amalgam over time
low
expansion
how many hours does it take for amalgam to COMPLETELY set?
24 hours
t/f when the alloy in powder form is mixed with liquid mercury a chemical reaction occurs
true
The chemical reaction that occurs when alloy and mercury are mixed has ____ phases, what are they?
THREE phases
Gamma phase
Gamma-1 phase
Gamma-2 phase
what type of amalgam does not have a gamma-2 phase? what is the benefit of this?
High Copper amalgams
superior in their clinical performance, reduced corrosion, higher strength and margins that hold up better
what is the strongest chemical reaction phase?
gamma phase
what is the weakest chemical reaction phase?
gamma-2 phase
what is used to control the rate of set of amalgam?
TIN
copper reacts with ____ so its not available to act in with the mercury (gamma-2 phase)
tine
what is tarnish a result from?
contact with oxygen, chlorides and sulfides in mouth
what results from contact with oxygen, chlorides and sulfides in the mouth?
TARNISH
t/f the rougher the surface the more tarnish
true
______ can occur from a chemical reaction between the amalgam and substacnes in saliva and food
corrosion
corrosion is an _____ of amalgam becuse of ______ reaction between amalgam and substances in _____ or _____
oxidation
chemical
saliva
food
t/f corrosion can occur when two dissimilar metals interact in a solution containing electrolytes
true
if galvanism occurs one of the metals ______ causing corrosion
oxidizes
______ takes place within the amalgam through interactions of its metal components, it ____ the amalgam over time, ____ tooth structure and lead to ______ of margins
corrosion
weakens
stains
deterioration
most amalgams are ____ copper alloys
high
high copper alloys ______ gamma 2 reaction, are more _____, have less _______ of ______ and less _____
eliminate
durable
deterioration
margins
corrosion
gradual change in shape of the restoration from compression by the opposing dentition during chewing or by pressure from adjacent teeth
CREEP..jeepers creepers where'd you get them peepers
t/f creep occurs more now that amalgams are high copper
FALSE-occurs LESS!
creep is a phenomenon associated with what chemical phase of alloy and mercury being mixed?
gamma -2 (found in low copper amalgam alloys not high remember.....pause pause pause for dramatic effect okay now you can move on)
what happens if an amalgam contracts excessively?
opens gaps at the margins=leakage!
too much contraction of an amalgam results in open ____ causing ____ _____ and what would that cause (I am going to make you think)
gaps
marginal leakage
HYPERSENSITIVITY
what happens if there is too much expantion of an amalgam
puts pressure on the cusps causing pain when biting and could result in a fracture
where does expantion of an amalgam put pressure?
on the cusps
if there is pain upon biting down what is that an indication of?
poss perio ligament, abcess, high filling
what is is pain upon releasing of pressure an indication of?
fracture of tooth
amalgams are strongre in compression than _____ or ____ _____
composites
glass ionomers
t/f amalgams are weak in tension and shear and therefore require adequate bulk to resist breaking
true (I can't word somethint that nicely and make it false duh!)
what does amalgam need to resist breaking?
bulk
high copper amalgams have a high _____ ______ strength
EARLY compressive strength
what type of amalgam has a high early compressive strength
high copper amalgams
what is the time frame to be considered an early compression vs late compressive strength
LESS than 24 hours for early...24 hours would be LATE
