Amalgam Flashcards
Dental amalgam is a combination of…
Liquid elemental mercury and a metal alloy
Components of metal alloy in dental amalgam
Silver and Copper – strength
Tin– provider of corrosion products
Zinc– deoxidizer
𝝲 phase
composed of unreacted silver-tin alloy
STRONGEST
LEAST CORROSION RESISTANT
𝝲1 phase
silver-mercury matrix
2nd strongest (after 𝝲 phase)
𝝲2 phase
tin-mercury matrix
weak and susceptible to corrosion and creep
Corrosion can seal the restoration margin over time, but 𝝲2 has weak mechanical properties, so it is unwanted
Amalgam reaches its peak strength after _____ hrs
24
Over-Triturated amalgam appearance
warm, soft, sets quickly
Under-Triturated amalgam appearance
dry, crumbly, sets quickly
Low Copper Amalgam
under 12% Cu
Yields in the production of 𝝲, 𝝲1, and 𝝲2 phases
High Copper Amalgam
contains over 12% Cu
Yeilds ONLY 𝝲 and 𝝲1 (NO 𝝲2 PHASE WITH HIGH COPPER)
Minimum corrosion products and creep
Spherical Alloy Particles
small spheres
more plastic
quicker set time
condenses better– ideal for pins and slots
more durable
Admixed Alloy Particles
spherical + irregular particles
needs higher condensation forces
yields better proximal contacts with adjacent teeth
Class V amalgam preps must have ________ _______ and ________ features
Occlusal divergence and retention features
Occlusal divergence required due to the enamel rod orientation
Retention features like gingival or circumferential grooves can be used
Mercury Toxicity cause:
80% of elemental mercury is absorbed through the lungs making INHALATION the greatest risk
Acute Mercury Toxicity can result in…
muscle weakness (hypotonia)
GI trouble
Loss of hair (alopecia)
