Amalgams copper content

The copper-rich amalgams have performed well in clinical trials in which they were compared with alloys having lower copper content. An improved marginal stability was observed, which may be associated with a longer clinical lifetime (136). These amalgams have also been called non-y2 amalgams, where refers to the compound Sn Hg comprised of Sn Hg [11092-12-9] and Sn Hg [11092-11-8]. 

One of the serious defects of the conventional amalgams is the corrosion of the Sn Hg phase, which is normally absent or, if it forms, mostiy disappears in amalgams with the increased copper content hence, the term non-y2 amalgams. The phases present in two conventional amalgams used in clinical testing (56,58,62) are... 

Amalgams for dental restorations are classified by their copper content in two basic types ... 

Fig. 3. Evans-diagram for the cementation of Cu2+ and Pb2 with zinc amalgam of different zinc content. If the zinc concentration in the mercury employed for this special extraction technique is low, the anodic zinc-dissolution current density may be diffusion controlled and below the limiting cathodic current density for the copper reduction. The resulting mixed potential will lie near the halfwave potential for the reaction Cu2+ + 2e j Cu°(Hg) and only Cu2 ions are cemented into the mercury.

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