Amalgam types

[booshwa]

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Does anyone know if people still use low-copper amalgams? If so what benefit does it have over a high-copper amalgam?

 

[UBTom]

High-Cu amalgams have better corrosion resistance. As a side effect it also gives somewhat better mechanical properties-- Corrosion and pitting causes mechanical weakness. High-Cu amalgams typically last 2-3 times longer than a conventional low-Cu amalgam.

Still have to condense it properly though so you can remove as much of the Gamma-2 mercury phase as possible, which if not removed causes mechanical weakness.

HTH.

 

[booshwa]

Still have to condense it properly though so you can remove as much of the Gamma-2 mercury phase as possible, which if not removed causes mechanical weakness.

I thought that high copper (above 12%?) amalgams do not have the gamma-2 phase but instead have the eta phase (Cu-Sn).

Everything that I've read says that the high copper amalgams have greater strength, with less tarnish and corrosion and less creep. Am I just missing some reason why the low Cu may be used, or is it just an antiquated material?

 

[UBTom]

OK, I looked up Sturdevant to refresh my memory on obscure details. 😀

My bad, not just gamma-2, but whatever mercury-rich phase should be removed as much as possible by proper condensation.

Still couldn't find anything in there that says low-Cu amalgams have any advantages over high-Cu amalgams though.