olola's version from 2016-09-19 02:36


Question Answer
Dental amalgam is produced by mixing liquid mercury with solid particles of an alloy containing predominantly what 3 metals?silver, tin, and copper
Silver alloy (amalgam) has mercury and what 3 metals predominantly? what 3 metals in small quantities?Silver, Tin & Copper (predominantly); Indium, Palladium & Zinc (small quantities)
The absence of which phase (what does you mean) is responsible for the longevity of high copper amalgam restorations?Gamma-2
_____ ______ is the elastic-like force existing on the surface of a body which tends to minimize the area of the surface, caused by asymmetries in the intermolecular forces between surface molecules.Surface Tension
Amalgams are generally grouped into two subtypes based on the amount of _______ in the alloyCopper (high copper or low copper amalgams)
subtype of Amalgam with greater than 13% copperHigh copper amalgam
subtype of Amalgam with 2-5% copperLow copper amalgam
what is Dispersalloy's size/shape of particles... is it high or low copper?Admixed (spherical and lathe) & High copper
Phase of amalgam that is responsible for corrosion of dental amalgamGamma-2
T/F: Under-trituration leads to a grainy, crumbly mixTrue
What sets fastest Lathe-cut, Spherical, or admixed?Spherical
High copper or low copper has greater corrosion and marginal breakdown?Low copper (b/c has gamma-2 phase)
There is no Gamma-2 phase amalgam in amalgams with high _____Copper
Amalgam has a compression strength of 300-500 mPa when at a preparation depth of ____ mm2mm
which has a higher compressive strength, High Copper or Low copper amalgams?High copper
which has a higher compressive strength, irregular or spherical amalgam?spherical
T/F: occlusal forces are both compressive and tensileTrue
Which has greater creep, high copper or low copper amalgam?low copper
Amalgams with ____ have greater expansion if moisture is not controlled during restoration.Zinc (this is why they're not used anymore)
Which is most toxic because it is easily absorbed.... inorganic mercury, organic mercury or elemental mercury?Organic mercury
What is the half-life of mercury?60-90 days
Most of us have approximately ___ nM of mercury in our bodies from the several sources including air, water, fish, food and amalgam restoration5 nM
The World Health Organization states that amalgam only counts for _________% of mercury emissions5%
what is the source of most mercury that we are exposed to?Food

Dispersalloy or Titin

Question Answer
reaches 30-50% of final strength at 15 minutesDispersalloy
reaches 50-80% of final strength in 1 hourDispersalloy
reaches 100% of final strength In 7 daysDispersalloy
80-90% of final strength at 15 minutesTytin
100% of final strength in 2-3 daysTytin
Spherical silver amalgamTytin

how much mercury does it take to show signs

Question Answer
lowest known toxicity3 micrograms/kg
paresthesia500 micrograms/kg
ataxia1000 micrograms/kg
joint pain2000 micrograms/kg
death4000 micrograms/kg

which phase of amalgam am I?

Question Answer
Ag2Hg3Gamma 1
Sn7-8HgGamma 2
I'm responsible for corrosion of dental amalgamGamma 2

types of amalgam based on size/shape

Question Answer
Irregular-shaped particles are cut with sizes ranging from 100-200 microns. The internal stresses within the polycrystalline particle must be relieved by heat-treatment/annealing.Lathe-cut alloys
Silver alloy particles ranging in size from 2 - 43 microns that require less mercury.spherical
mixture of the two forms-lathe and sphericalAdmixed silver alloy (e.g. Dispersalloy)

which component of amalgam have the following significance (effect)

Question Answer
Increase strength, high setting expansionSilver (Ag)
Decrease strength, decrease setting expansion, increase setting timeTin (Sn)
Reacts with tin, reducing gamma-2 formation, increases strength, reduces tarnish and corrosion, reduces creep, reduces marginal deterioration.Copper
Decreases surface tension leading to reduction in the amount of mercury required which in turn reduces the amount of mercury vapor liberated, reduces creep and marginal breakdown, increases strengthIndium
Is found only in admixed alloy amalgams (e.g. Indisperse)Indium
Added as a processing aid to minimize oxidation of other elements; reacts with moisture intraorally to cause post-op expansionZinc
Reduces corrosion, produces greater luster, found in both spherical and admixed (phase dispersed). (Example: Valiant PhD)Palladium
Contemporary amalgams now don't have _______ because of the tendency to cause post-op expansionZinc