Methods: A localised electrochemical method, scanning electrochemical microscopy (SECM), uses an ultramicroelectrode (UME) to generate protons just above a small portion of an enamel surface creating localised, controlled and measurable acidic challenges. Both the time and flux of the protons produced are quantifiable and can be varied. Measurements were made on polished enamel discs from the buccal sides of bovine incisors which were polished to 0.25 µm using diamond paste.
Results: The electrochemical technique results in etch features in the enamel samples. Treatment with fluoride alters the pit shapes making them wider, suggesting some protection to acid challenges. A model has been designed to describe the etching process and to better understand the kinetics of dissolution. White light interferometry (WLI) has been used to discover the nature of the etching process and highlights features such as enamel rods where differential rates of dissolution are apparent. The implications of the kinetic results for the treatment of acid erosion are outlined.
Conclusion: SECM has proven to be a powerful and versatile technique for studying acid induced erosion. The high resolution technique of WLI has proven invaluable in characterising the size and morphology of the etch pits produced, while modelling of the pit shape elucidates the kinetics of dissolution. Dissolution is observed to be a fast process and fluoride has some influence on the kinetics of dissolution, which is shown by the model.