Initial corrosion of amalgams in vitro

Area of Science:

• Dental Materials Science
• Biomaterials Science
• Environmental Health

Background:

• Dental amalgam, a widely used restorative material, consists of alloys containing mercury, silver, copper, and tin.
• Concerns exist regarding the potential release of metallic ions from amalgam restorations into the oral environment.

Purpose of the Study:

• To quantify the release of copper, mercury, silver, and zinc from freshly prepared dental amalgams into artificial saliva.
• To compare initial metal ion release rates with established dietary intake values.

Main Methods:

• Three brands of dental amalgam (two lathe-cut, one dispersed-phase) were prepared and immersed in artificial saliva shortly after trituration.
• Static immersion tests were conducted for up to four days.
• Metal ion concentrations were measured using sensitive nuclear tracer techniques.

Main Results:

• Initial mercury release from new amalgam specimens was significantly higher than long-term release from aged amalgams, exceeding it by over two orders of magnitude.
• Within the first 24 hours, mercury release from two typical amalgam fillings could surpass twice the daily dietary intake.
• Initial release of copper and zinc was considerably lower than dietary intake, while silver release was comparable.

Conclusions:

• Freshly placed dental amalgams exhibit a high initial mercury release rate, which diminishes over time.
• While acute mercury exposure from new amalgams can be substantial, it represents an infrequent scenario.
• The release of copper, zinc, and silver from new amalgams is generally within or below typical dietary intake levels.