Corrosion of dental aluminium bronze in neutral saline and saline lactic acid.
OBJECTIVE
To compare the corrosion behaviours of two aluminium bronze, dental casting alloys during a standard immersion test and for immersion in neutral saline.


METHODS
Cast specimens of aluminium bronzes with 1.4 wt% Fe (G) and 4 wt% Fe (N) were subject to progressively longer periods (up to in total 7 days) immersed in 0.1 M saline, 0.1 M lactic acid solutions and examined by scanning electron microscopy with EDX analysis. Immersion in 0.1M neutral saline was for 7 days.


RESULTS
In the acidic solution, exposed interdendritic volumes in alloy N corroded completely away in 7 days with dissolution of Ni-enriched precipitate species as well as the copper-rich matrix. Alloy G begins to corrode more slowly but by a similar mechanism. The number density of an Fe-enriched species is insufficient to maintain a continuous galvanic potential to the copper matrix, and dissolution becomes imperceptible. In neutral saline solution, galvanic action alone caused pit-etching, without the dissolution of either precipitate species.


CONCLUSIONS
The upper limit for the total dissolution of metallic ions in the standard immersion test can be set at 200 microg cm(-2). Aluminium bronze dental alloys can be expected to release both copper and nickel ions into an acidic oral environment.
Tibballs
J E
JE
NIOM, Nordic Institute of Dental Materials, Kirkeveien 71B, 1305 Haslum, Norway. john.tibballs@niom.no
Erimescu
Raluca
R
D000535:Aluminum; D003300:Copper; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003735:Dental Casting Technique; D004577:Electron Probe Microanalysis; D007101:Immersion; D007501:Iron; D019344:Lactic Acid; D008345:Manganese; D008422:Materials Testing; D009532:Nickel; D012965:Sodium Chloride; D015032:Zinc
D003722:Dental Alloys; D019344:Lactic Acid; D008345:Manganese; D012965:Sodium Chloride; D003300:Copper; D009532:Nickel; D000535:Aluminum; D007501:Iron; D015032:Zinc