Metal release from dental biomaterials.

Levels of corrosion products released from dental alloys in natural or synthetic saliva, i.e. from amalgams, cobalt, gold, nickel, iron, or titanium based alloys have been surveyed. The amounts of Ag, Au, Cd, Co, Cr, Cu, Hg, Mo, Ti or Ni released from such alloys, either in vitro or in vivo during animal tests or during clinical usage have been compiled. The quantities released have been adapted to a 'standard restored man' with a specified number of restorations or a specified construction with a defined surface area, and compared to man's food and drink intake of similar elements. This was done as one approach to a security analysis of wearing dental alloys. In view of the assessment of extensive corrosion testing using electrochemical methods, rather scarce information seems presently available pertinent to release kinetics of specific elements in various biological environments like saliva or saliva substitutes. Several examinations indicate that mercury released from amalgams could be a substantial part of man's daily intake of this element, e.g. in the initial period following insertion, as well as on a long-term basis. From a copper amalgam cadmium could be released in vitro in amounts close to food and drink intake. The mercury release from the amalgam surface seems to be strongly influenced by the interaction of mechanical forces, e.g. chewing, and seems to be released according to a cyclic pattern. From a base metal alloy with high nickel content nickel could be released in vitro at the same level as from food and drink intake. However, from cobalt based alloys the nickel release seems insignificant in this context. The elemental release from the other alloys seemed to be far below the intake of similar elements from food and drink. Release under static and dynamic conditions has been discussed.