Quiz 6 Flashcards
What is amalgam made of?
Alloy of mercury
What is in the alloy of mercury?
Silver
Copper
Tin
Zinc
What are the types of particle alloys?
Lathe-cut
Spherical
Admixed
Grind into fine particles, irregular shape
Lathe-cut alloy
Spray molten metal
Spherical alloy
Mix of lathe-cut and spherical
Admixed alloy
More force to condense irregular shapes
Lathe-cut particle shape
Cannot be condensed easily with small condenser
Less volume, less Hg required to wet surface
Spherical particle shape
Better for proximal surfaces
Holds matrix band against adjacent tooth better
Lathe-cut and admixed particle shape
Mixing of liquid mercury and powdered alloy
Amalgamation
machine that mixes the mercury and powder together
Triturator/amalgamator
-results in voids and gaps
-contributes to tarnish, surface oxidation, corrosion, percolation
Inadequate mercury
Lathe-cut – irregularly cut particles
Higher silver/lower copper content
Conventional recipe of low-copper dental amalgam
-silver and tin react
-Amalgam is strongest as can be
-Most corrosion resistant
Gamma phase
-silver and mercury react
-Somewhat strong
-Corrosion resistant but brittle
Gamma 1 phase
-tin and mercury react
-weakest and most corrosion prone
Gamma 2 phase
solid formed from material dissolving in liquid
Percipitation
Begins in gamma 1 and 2 phase
Continues up to 24 hours or until mercury is consumed
Percipitation
slow change in shaped caused by compression
Creep
o Causes open, chipped, and/or overhanging margins
o Eliminated with high copper content
Creep
o Dominates market
o Eliminated the gamma 2 phase
o High copper content = less creep
o Mix: admixed or spherical
High-copper dental amalgam
What are the properties of amalgam?
o High compressive strength
o Minimal dimensional change
o Creep
o Tarnish
o Corrosion
o High thermal conductivity
contain amalgam when condensed into proximal surfaces
Matrix band
aid in adapting the matrix tightly
Wedges
final polish in mouth for amalgam
Tin oxide
What is the life expectancy of amalgam?
12-18 years
Mercury toxicity most significant from what?
Vapor
Contains noble metals (Gold, platinum, palladium)
Resistant to corrosion and tarnish
Precious metallic alloy
Contains base metals (Silver, copper, nickel, tin, zinc)
Susceptible to corrosion and tarnish
Nonprecious metallic alloy
o Only used provisionally
o Prefabricated crowns
o Pediatric patients with extensive caries
Stainless steel crowns
