Susceptibility of deciduous and permanent enamel to dietary acid-induced erosion studied with atomic force microscopy nanoindentation

The initial stages of dental enamel demineralization by dietary acids are of particular clinical relevance. Some authors have reported a difference in the susceptibility of deciduous and permanent enamel to erosion, although other studies could not confirm these findings. The aim of the present study was therefore to investigate whether there are differences in the susceptibility of deciduous and permanent enamel to dietary acid induced erosion (demineralization). Nanoindentation combined with atomic force microscopy was used to investigate the erosive effect of four different drinks (cola, lemonade, juice drink, and water) on enamel at early stages in vitro. Surface nanohardness and reduced elastic modulus were obtained for the soft drink-treated enamel samples as a function of the exposure time. The results obtained showed that the four drinks had widely differing erosive effects due to their diverse compositions. Water did not show statistically significant changes in nanomechanical properties for all exposure times compared with untreated enamel. Exposure of enamel to cola, lemonade and the juice drink led to a statistically significant surface softening of the enamel with cola and the lemonade having a much stronger softening effect than the juice drink. For longer exposure times enamel softening increased for cola and lemonade and stayed unchanged for the juice drink. Deciduous enamel was not found to be more susceptible to erosion than permanent enamel under the conditions of the present study.