31: Dental amalgam

31

Dental amalgam

Figure 31.1 Setting reaction of conventional amalgam alloy.

c31-fig-0001

Figure 31.2 Setting reaction of dispersion-modified (admixed) amalgam alloy.

c31-fig-0002

Figure 31.3 Setting reaction of single-phase amalgam alloy.

c31-fig-0003

Figure 31.4 Increase in amalgam compressive strength with time.

c31-fig-0004

Figure 31.5 Corrosion process with a conventional dental amalgam.

c31-fig-0005

Table 31.1 Specification composition limits (wt.%) of amalgam alloys

c31-tbl-0001.jpg

Table 31.2 Compositions (wt.%) of amalgam alloys

c31-tbl-0002.jpg

Table 31.3 Average properties of dental amalgams

c31-tbl-0003.jpg

Dental amalgam is produced by reaction (trituration) of mercury with silver–tin alloy particles. However, clinical use of amalgam is decreasing due to concern over its mercury content as well as environmental issues associated with waste amalgam disposal.

31.1 Dental amalgam alloy

Alloys are supplied as irregular (lathe-cut) particles, spherical/spheroidal particles, or a mixture of both, and they consist of silver and tin with lesser contents of copper and zinc (Table 31.1). Zinc-containing alloys have ≥0.01% zinc content whereas nonzinc alloys have <0.01% zinc.

Alloy type and the alloy-to-mercury ratio affect the properties of the set amalgam. The mix contains insufficient mercury for complete reaction and set amalgam contains 11–13% unreacted Ag3Sn particles.

1 Lathe-cut alloys: Particles are irregularly shaped (60 – 120 × 10 – 70 × 10 – 35 μm), primarily Ag3Sn (γ phase) with lesser amounts of Cu3Sn (ε) and Cu6Sn5/>

Only gold members can continue reading. Log In or Register to continue

Stay updated, free dental videos. Join our Telegram channel

Jan 1, 2015 | Posted by in Dental Materials | Comments Off on 31: Dental amalgam

VIDEdental - Online dental courses

Get VIDEdental app for watching clinical videos