Amalgam

Dental amalgam
Sandra Bērziņa

Definitions
Amalgam: alloy of mercury with one or more other metals
Amalgam alloy: alloy which combines with mercury to form amalgam
Dental amalgam alloy: alloy that is combined with mercury to form amalgam used for dental purposes

Dental amalgam
• Dental amalgam has been the most widely used material for the restoration of posterior teeth due to:
– High strength and durability
– Ease of use
– Good physical characteristics

• However, its use has decreased over the past decade due to concerns regarding:
– Esthetics
– Mercury content

History
• Amalgam was first used by the Chinese.
There is a mention of Silver – Mercury paste by Su Kung (A.D. 659) in the
Chinese materia medica
• 1826
– introduction of Silver – Mercury paste (pated`argent) by Peter O. Taveau of Paris, France

History
• 1833
–

Crawcour brothers introduce amalgam to US
•

powdered silver coins mixed with mercury
–

expanded on setting

• 1895
–

G.V. Black develops formula for modern amalgam alloy
•

67% silver, 27% tin, 5% copper, 1% zinc
–

overcame expansion problems

History
• 1960’s
– conventional low-copper lathe-cut alloys
• smaller particles

– first generation high-copper alloys
• Dispersalloy (Caulk)
– admixture of spherical Ag-Cu eutectic particles with conventional lathe-cut
– eliminated gamma-2 phase

Classification
According to content
– Silver amalgam: Silver more than 65%
– Copper amalgam: 70% Hg and 30% Cu
According to presence or absence of Zn
Zinc containing alloys – more than 0.01% Zn
Zinc free alloys – less than 0.01% Zn

Classification
• According to Copper content
– Low copper alloys (2-4-6% Cu)
– High copper alloys (9-30% Cu)
According to the shape of alloy particles
- Lathe cut
- Spherical
- Admixture

Classification

Spherical

Cu

Cu

Admixed

Lathe cut

Cu

Cu

Classification
• According to number of metals in alloy
– Binary