Surface Chemistry of a High-copper Dental Amalgam

• Published in: Journal of dental research Vol. 77; no. 12; pp. 1999 - 2004
• Main Authors: McDermott, A.J., Kothari, S., Short, R.D., van Noort, R., Alexander, M.R.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.12.1998; SAGE PUBLICATIONS, INC
• Subjects: Copper - analysis; Copper - chemistry; Dental Amalgam - analysis; Dental Amalgam - chemistry; Dental Polishing; Dentistry; Electron Probe Microanalysis; Microscopy, Electron, Scanning; Models, Chemical; Models, Structural; Surface Properties; Time Factors; amalgam; XPS; surface chemistry; mercury
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/00220345980770120801

In amalgam, mercury is intended to take the form of stable intermetallic compounds. Any mercury leakage must therefore come from free mercury not involved in such compounds. Thus, a knowledge of the exact surface chemistry of dental amalgam is necessary if this phenomenon is to be understood. From XPS and EDS analyses, a model of the surface chemistry of amalgam is proposed which fully characterizes all the phases that are present. The data show the surface to have a composition different from that of the bulk, being comprised of a hydrocarbon deposit and adsorbed water covering the intermetallic phase γ2 (Sn6-8Hg), tin (iv) oxide, and mercury in a free state. After amalgamation, the amount of mercury at the surface decreases with time and eventually attains a constant concentration, where it is all involved in the γ2 phase, leaving no free mercury. A model is proposed for the surface of amalgam and the changes in this model with time.