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International Journal of Spectroscopy
Volume 2011 (2011), Article ID 236496, 9 pages
Research Article

Effect of Artificial Saliva on the Apatite Structure of Eroded Enamel

1Department of Earth Sciences, University of Hamburg, Grindelallee 48, 20146 Hamburg, Germany
2Department of Preventive, Restorative and Pediatric Dentistry, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH—3010 Bern, Switzerland
3Division of Orthodontics, Department of Orofacial Sciences, The University of California San Francisco, 707 Parnassus Avenue, San Francisco, CA 94143-0438, USA
4Department of Orthodontics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany

Received 25 March 2011; Accepted 2 May 2011

Academic Editor: Sergio Armenta Estrela

Copyright © 2011 Xiaojie Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Citric acid-induced changes in the structure of the mineral component of enamel stored in artificial saliva were studied by attenuated total reflectance infrared spectroscopy as well as complementary electron probe microanalysis and scanning electron microscopy. The results indicate that the application of artificial saliva for several hours (the minimum time period proved is 4 h) leads to slight, partial recovering of the local structure of eroded enamel apatite. However, artificial saliva surrounding cannot stop the process of loosening and breaking of P–O–Ca atomic linkages in enamel subjected to multiple citric acid treatments. Irreversible changes in the atomic bonding within 700 nm thick enamel surface layer are observed after three times exposure for 1 min to aqueous solution of citric acid having a pH value of 2.23, with a 24-hour interval between the individual treatments. The additional treatment with basic fluoride-containing solutions (1.0% NaF) did not demonstrate a protective effect on the enamel apatite structure per se.