The early stages of native enamel dissolution studied with atomic force microscopy

Food-induced demineralization (erosion) is one of the key factors in surfac e structural changes of tooth enamel, with soft drinks being a significant etiological agent. The objective of this study was to measure early stages of enamel loss with high accuracy on native enamel surfaces combined with q ualitative observations of changes in the surface morphology using the atom ic force microscope (AFM). Native unerupted third molar surfaces were partl y covered with a gold reference layer. Samples were imaged with the AFM bef ore dissolution (at baseline) and after exposure to three different drinks (mineral water, a "toothkind" blackcurrant drink, and a lemon and lime juic e drink) at five different exposure times (15 min, 30 min, 1 h, 2 h, and 3 h). The changes in the surface morphology were investigated qualitatively a s well as quantitatively. This study showed that the maximum material loss occurred at the aprismatic parts of the enamel close to the perikymata. The maximum enamel loss was greatest for the lemon and lime juice drink and lo west for water. A two-way ANOVA of the transformed data, employing the natu ral logarithm, showed a statistically significant difference between both t he drinks and the exposure time at a 95% confidence level (P = 0.000). This demonstrates that the AFM is a suitable tool for measuring early stages of enamel demineralization. (C) 2000 Academic Press.