title: Corrosion potential recovery of dental amalgam restorations following prophylaxis.
abstract: OBJECTIVE
  Dental amalgam restorations are subjected to abrasion during selective prophylaxis that can damage or remove the protective oxide and result in increased rates of corrosion and chemical dissolution of mercury. It was the objective of this research to study the corrosion potential change of dental amalgam restorations to obtain an indication of the time required for in vivo repassivation following prophylaxis.
  
  
  METHODS
  The corrosion potentials of 27 Class I and Class II amalgam restorations were measured pre- and post-prophylaxis using a high impedance voltmeter and a Ag/AgCl micro-reference electrode. Prophylaxis was performed for approximately 2s on each amalgam surface using a slow-speed handpiece with a rubber-cup and commercial abrasive paste. Subjects thoroughly rinsed before the post-prophylaxis corrosion potentials were measured. The data were analyzed using a confidence interval, a t-test and correlation analysis.
  
  
  RESULTS
  The pre- and post-prophylaxis mean corrosion potentials were, respectively, -132 (27)mV and -126 (27)mV. The mean of the differences between the pre- and post-prophylaxis corrosion potentials was 6.1 (28)mV, with an associated 95% confidence interval of (-4.8, 17)mV. A t-test showed the mean absolute difference in corrosion potential was less than 50 mV (p<0.0001).
  
  
  CONCLUSIONS
  The results of this study show that the post-prophylaxis recovery of the corrosion potential of amalgam restorations occurred by at most 10-44 min, indicating that the period of elevated corrosion rate and elevated chemical dissolution rate of mercury, due to oxide damage or removal, may be short-lived.
authors.affiliation: Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, 5981 University Avenue, Halifax, Nova Scotia, Canada B3H 3J5. Elliott.Sutow@dal.ca
authors.forename: Elliott J
authors.initials: EJ
authors.lastname: Sutow
authors.forename: J Peggy
authors.initials: JP
authors.lastname: Maillet
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Maillet
authors.forename: Gordon C
authors.initials: GC
authors.lastname: Hall
authors.forename: Michele
authors.initials: M
authors.lastname: Millar
mesh_terms: D000328:Adult; D003343:Corrosion; D003723:Dental Amalgam / Q000737:chemistry*; D003777:Dental Prophylaxis; D003793:Dental Restoration, Permanent; D005260:Female; D006801:Humans; D008297:Male; D011199:Potentiometry
chemical_list: D003723:Dental Amalgam