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57 Cards in this Set

  • Front
  • Back
What percentage of restorations utilize amalgams?
75%
Amalgam has served as a restorative material in dentistry for how many years?
Over 165 years
T/F Hypersensitivity to amalgam is common
False rare
Amalgam _______ at a similar rate as tooth structure
wears
Amalgam is the least ______ of the long term materials
expensive
What is the composition of amalgam?
Silver (Ag) 40‐60%; Tin 27‐30%; Copper (Cu) 6‐30%; Zinc (Zn) 0.01‐2%; Palladium (Pd) less than 1%; Indium (In) 10‐15% in the Hg (Steve Thompson Can’t Zee Past Insults)
An admix of amalgam is a mixture of what?
Mixture of lathe cut and spherical particles. (Irregular was first used – lathe cut type)
When an alloy containing 27% tin is slowly cooled below a temperature of ___, an intermediate compound Ag3Sn known as the _____ phase is produced ***
480° and gamma
Mercury diffuses into the γ phase and reacts with the silver and tin portions of the particles forming two compounds?
1. Silver‐mercury (γ1 phase: Ag2Hg3)
2. Tin‐mercury (γ2 phase: Sn7‐8Hg)
During the reaction Mercury dissolves into the amalgam. What amount dissolves into Copper, Silver, and Tin?
1 mg Hg in copper, 10 mg of Hg in Silver, 170 mg of Hg in Tin
What phase causes the γ2 phase to be eliminated?
ε phase
Which phase is the weakest and most susceptible to corrosion?
γ2 phase
What is the compressive strength of amalgam?
Good: (200 MPa in 1 hour)
Is the tensile strength of amalgam good?
No; (50 MPa)
The elastic modulus is considered?
Good ( 11‐62 MPa)
What is creep as it relates to amalgams?
Permanent deformation under static loads (0.05 – 6.3%)
Dimensional changes are greatest during the first _____.
20 minutes (contraction)

after that expansion then stable at 6‐8 hours, capable of normal function after 24‐48 hours.
When zinc containing alloy gets contaminated with water it will cause?
Excessive expansion
Corrosion: Progressive ___________of a metal by chemical or electrochemical reaction.
Destruction (Porosity > marginal integrity < Loss of strength and release of metallic products)
Phosphate buffer solutions _________ the corrosion process (saliva).
inhibit
Zinc cause too much ________. Therefore, new products have aimed to remove zinc.
expansion
Admixed allows for _______ time compared to spherical.
more
True or False: Even 2‐3 sec difference can produce an over or under mixed amalgam.
True
A dull and crumbly amalgam would indicate what type of error?
Undermixed
A soupy and tends to stick to walls of the capsule would indicate?
Overmixed
What instrument is used to place the amalgam restoration?
Amalgam carrier
Ivoclar‐Vivadent used in the dental clinic eliminates which phase?
γ2 phase
Lateral condensation is important for __________ particles of amalgam
spherical
Use a flat‐faced small __________ to condense the amalgam over the pulpal and gingival floor of the preparation.
condenser
Each increment of amalgam should fill ____ to ____ the cavity prep.
1/2 to 1/3
Overpack prep by ______ .
1mm
Condensation of the mix should be completed in ______ to ______ minutes.
2.5 to 3.5
True or False: Deep occlusal grooves should be carved into the restoration?
False
An amalgam restoration overcarved more than _____ should be replaced.(referred to as ditching)
0.2 mm
To smooth the carved surface you may use a _____ _________ _________.
Dry cotton pellet
Try to avoid occlusal contacts on the _________.
Inclines
Finishing and Polishing of the restoration will make it less prone to ___________ and ‐___________.
Tarnishing and corrosion
What is the recommended sequence for performing an amalgam restoration?
1. Field Isolation
2. Establish outline
3. Remove Caries
4. Smooth cavosurface angle
5. Place base if deep or close to pulp.
6. Insert amalgam as explained.
_________ __________ wears at a rate similar to tooth structure?
Dental Amalgam
What type of Amalgam do we use at CWRU?
Valiant PhD by Ivoclar Vivadent

High Copper Alloy (to eliminate the gamma2 phase)
1. Higher Strength
2. Less Corrosion
3. Better longevity at the margins
What does Undermixed amalgam look like?
Dull and crumbly
What does properly mixed amalgam look like?
Shiny and separates in a single mass
What does overmixed amalgam look like?
Soupy and tends to stick to the walls of the capsule
What is creep, when referring to amalgams?
Permanent deformation under static loads (0.05-6.3%). Creep is especially prevalent in high mercury amalgams
What is the compressive strength like in amalgams?
Good (200 MPa in 1 hour)
What is the tensile strength of amalgam like?
Bad (43-58 MPa)
What is the elastic modulus like in amalgams?
Good (11-62 MPa)
Why do you tell patients not to eat anything for 1 hour after having an amalgam placed?
The amalgam reaction is not complete
What happens when a Zinc containing alloy gets contaminated with water?
Excessive expansion
What is the dimensional change of amalgam during the first 20 minutes?
Contraction
What is the dimensional change of amalgam after 20 minutes then stabilizes at 6-8 hours
Expansion
What is the Υ phase?
When an alloy containing Tin is cooled below 480 deg C an intermetallic compound is formed (Ag3Sn)
What happens when the Υ phase is mixed with mercury?
Υ1 phase (Ag2Hg3) Silver-mercury
Υ2 phase (Sn7-8Hg) Tin-mercury
What is the amalgamation reaction?
See Above
What causes the Υ2 phase to be eliminated within a few hours after its formation?
ε phase
What phase is the weakest and most susceptible to corrosion?
gamma 2 phase
How do amalgam particles present?
Irregular or Lathe-cut
Spherical
Admixed