Mechanism of Improved Corrosion Resistance of Zn-containing Dental Amalgams

Abstract

The aim of this study was to determine the mechanism of improved corrosion resistance of Zn-containing dental amalgams. Two Zn-containing conventional amalgams, their Zn-free counterparts, and three experimental amalgams (SnHg, ZnHg, and SnZnHg) were evaluated by the potentiodynamic polarization technique in 1% NaCl solution. The main difference between the two types of amalgams was found in their respective breakdown potentials at which passivity was destroyed. The breakdown potential of Zn-containing amalgams was about 200 mV more positive than that of the Zn-free amalgams. The improved stability of the Zn-containing amalgams has been attributed to the formation of a previously reported Zn stannate passive film which, according to the polarization data, is more resistant to the aggressive chloride ion than tin hydroxide that forms on Zn-free amalgams. The formation of Zn stannate was not found to affect the oxygen reduction reaction, the major cathodic reaction involved in the corrosion of dental amalgams.

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References

Brune, D. (1981): Corrosion of Amalgams, Scand J Dent Res 89 :506-514.

Brune, D. (1986): Metal Release from Dental Biomaterials, Biomaterials 7:163-175.

Clarke, M. and Elbourne, R.G. (1971): The Peculiarly Low Passivation Potentials of Some Intermetallic Tin Compounds, Electrochimica Acta 16:1949-1954.

Dean, S.W., Jr. (1986): Electrochemical Methods of Corrosion Testing. In: Electrochemical Techniques for Corrosion Engineering, R. Baboian , Ed., Houston: National Association of Corrosion Engineers, pp. 193-205.

Fontana, M.G. and Greene, N.D. (1978): Corrosion Engineering, 2nd ed., New York, NY: McGraw-Hill Book Company, pp. 297-345.

Gjerdet, N.R. and Berge, M. (1983): Liberation of Copper, Zinc, and Cadmium from Different Amalgams, Acta Odontol Scand 41:217-220.

Jensen, S.J. (1982): Corrosion Products of Dental Amalgam, Scand J Dent Res 90:239-242.

Jensen, S.J. ; Andersen, P; Olesen, K.B. ; and Utoft, L. (1975): The Location of Zinc in Dental Silver Amalgam, Scand J Dent Res 83:41-45.

Johansson, B. and Derand, T. (1983): Corrosion of Amalgams with Special Regard to Zinc , Scand J Dent Res 91:320-324.

10.

Jorgensen, K.D. and Esbensen, A.L. (1973): Gravimetrisk bestemmelse of dental amalgamers korrosion, Tandlaegebladet 77:162-170.

11.

Konozo, Y. ; Hayashi, I. ; Moore, B.K. ; Swartz, M.L. ; and Phillips, R.W. (1981): Change in Microstructure of Amalgams by Corrosion , J Kyushu Dent Soc 35:489-501.

12.

Leidheiser, H., Jr. ; Simmons, G.W. ; Nagy, S. ; and Music, S. (1982): Mossbauer Spectroscopic Study of the Corrosion Inhibition of Zinc by Cobalt Ions, J Electrochem Soc 129 :1658-1662.

13.

Leidheiser, H., Jr. and Suzuki, I. (1980): Toward a More Corrosion Resistant Galvanized Steel, Corrosion 36:701-702.

14.

Lin, J.-H.C. ; Marshall, G.W. ; and Marshall, S.J. (1983): Corrosion Product Formation Sequence on Cu-rich Amalgams in Various Solutions, J Biomed Mat Res 17:913-920.

15.

Marek, M. (1983): The Corrosion of Dental Materials. In: Treatise on Materials Science and Technology, Vol. 23, J.C. Scully , Ed., London: Academic Press, pp. 331-394.

16.

Mueller, H.J. (1987): Tarnish and Corrosion of Dental Alloys. In: Metals Handbook, 9th ed., Ohio: ASTM International, Metals Park, pp. 1340-1342.

17.

Phillips, R.W. (1982): Science of Dental Materials, 8th ed., Philadelphia, PA : W.B. Saunders Company, p. 311.

18.

Pourbaix, M. (1973): Lectures on Electrochemical Corrosion, New York: Plenum Press, pp. 111-115.

19.

Sarkar, N.K. and Eyer, C. (1982): Corrosion of Zinc in Dental Amalgams, IADR Prog & Abst 61: No. 446.

20.

Sarkar, N.K. and Eyer, C. (1983): Location of Zinc in a Conventional Dental Amalgam by Electroetching, J Dent Res 62:189, Abst. No. 177(AADR).

21.

Sarkar, N.K. ; Fuys, R.A., Jr. ; and Stanford, J.W. (1979): Application of Electrochemical Techniques to Characterize the Corrosion of Dental Alloys. In: Corrosion and Degradation of Implant Materials, ASTM STP 684, B.C. Syrett and A. A. Acharya, Eds., Philadelphia: American Society for Testing and Materials, pp. 277-294.

22.

Sarkar, N.K. ; Fuys, R.A., Jr. ; and Stanford, J.W. (1981): Application of Potentiokinetic Hysteresis Technique to Characterize the Chloride Corrosion of High-Copper Dental Amalgams. In: Electrochemical Corrosion Testing, ASTM STP 727, F. Mansfeld and V. Bertocci, Eds., Philadelphia: American Society for Testing and Materials, pp. 283-289.

23.

Sarkar, N.K. ; Marshall, G.W. ; Moser, J.B. ; and Greener, E.H. (1975): In vivo and in vitro Corrosion Products of Dental Amalgam, J Dent Res 54:1031-1038.

24.

Sarkar, N.K. ; Redmond, W. ; Schwaninger, B. ; and Goldberg, A.J. (1983): The Chloride Corrosion Behavior of Four Orthodontic Wires, J Oral Rehab 10:121-128.

25.

Scully, J.C. (1975): The Fundamentals of Corrosion, 2nd ed., Oxford: Pergamon Press, p. 101.

26.

Soderholm, K.-J.M. (1987): An X-ray Diffractometric Investigation of the Sn-Hg Binary System Within the 0-40% Hg Interval, J Dent Res 66:712-715.

27.

Steigerwald, R.F. (1968): Electrochemistry of Corrosion, Corrosion 24:1-10.

28.

Tomashov, N.D. (1966): Theory of Corrosion and Protection of Metals. New York: The McMillan Co., pp. 176-202.