Journal of Dentistry
Volume 35, Issue 5 , Pages 425-430, May 2007

In situ tracing the process of human enamel demineralization by electrochemical impedance spectroscopy (EIS)☆

  • Ying-Min Liao

      Affiliations

    • Department of Materials Science and Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
    • ,
  • Zu-De Feng

      Affiliations

    • Department of Materials Science and Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
    • Research Center for Biomedical Engineering, Xiamen University, Xiamen 361005, China
    • Corresponding Author InformationCorresponding author at: Department of Materials Science and Engineering, Xiamen University, Xiamen 361005, China. Tel.: +86 592 8778331; fax: +86 592 2183937.
    • ,
  • Zuo-Liang Chen

      Affiliations

    • Xiamen Stomatological Hospital, Xiamen 361005, China

Received 10 May 2006; accepted 29 November 2006.

Abstract 

Objective

The purpose of this study was to in situ characterize the demineralization (namely dissolution of hydroxyapatite) on the surface of the human enamel using electrochemical impedance spectroscopy (EIS) technology.

Methods

Fresh human third molars extracted without visible evidence of caries, were used in this study. After they were immersed in a demineralizing solution prepared from lactic acid and carboxy methyl cellulose sodium (Na-CMC) buffering at pH 4, demineralization happened on their surfaces. EIS of the specimens were measured at a series of immersed interval. X-ray diffractometer (XRD) were used to distinguish the microstructure of the surface layer of the specimens. The depositions that appeared in the demineralizing solution after 46h immersion were analyzed by fourier transform infrared spectrometer (FTIR).

Results

XRD analysis revealed that the percentage of intensity (I%) of HAP gradually decreased with the elapsed immersing time, which indicated the dissolution of HAP columns of enamel. Nyquist spectra were fitted with an equivalent circuit characterized by some parameters, such as Q and Rp (error<0.1%). Changes of the parameters’ values revealed that the rate of demineralization accelerated at the forepart of the demineralization, but slowed down beyond 70h immersion.

Conclusions

The results suggested that EIS was proved to be a useful method for in situ investigating and in vivo detecting the demineralization of the enamel.

Keywords: Hydroxyapatite, Demineralization, Electrochemical impedance spectroscopy (EIS), X-ray diffractometer (XRD)

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☆ The sound human third molars used in this investigation were those extracted under clinic orthodontic treatment at Xiamen Stomatological Hospital.

PII: S0300-5712(06)00228-4

doi:10.1016/j.jdent.2006.11.011

Journal of Dentistry
Volume 35, Issue 5 , Pages 425-430, May 2007

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