CORROSION OF AMALGAMS UNDER SLIDING WEAR

Objectives. During mastication, dental amalgams are simultaneously sub jected to corrosion by the oral environment and to a sliding-wear proc ess by biting forces. In the present study, the effect of sliding wear on the corrosion behavior of two high-copper denial amalgams was inve stigated. Methods. An experimental apparatus was utilized that allows electrochemical testing under sliding-wear conditions. Corrosion poten tial measurements and anodic polarization scans were conducted in 0.1 M NaCl solution under sliding wear to characterize the behavior of two commerical, high-copper, single composition dental amalgams. In addit ion, long duration tests were conducted to assess possible corrosion a nd wear synergistic effects. Results. The results showed that sliding wear caused a sharp reduction in the corrosion potential, a significan t increase in the corrosion rate and a decrease in the repassivation r ate of both amalgams. These effects are due to the mechanical removal by the wear process of the surface protective film formed on dental am algams. The simultaneous action of sliding wear and corrosion can also induce embrittlement that leads to cracking. Significance. The presen t evidence suggests that this cracking may be one of the major contrib utors to marginal failures of dental amalgam restorations.