Surface nanohardness of enamel after an erosive challenge; a literature review

The present article aimed to systematically review studies investigating enamel surface nanohardness change following an erosive challenge by acidic beverages. Additionally, we aimed to identify study variables that affect nanohardness reduction and give more insight on how these variables contribute to enamel erosion. A rigorous literature search was performed; using the keywords: 'enamel' 'erosion' and 'nanoindentation'. Articles using nanoindentation technique and described the study design, type of indenter, beverages and length of erosive challenges were selected. A total of 17 articles fit our inclusion criteria and were included in this systematic review. The studies included performed erosive challenges using different beverages such as; carbonated drinks, dietry acids, wine and fruit juices with a pH range 2.3-6.3 and various immersion times (0s-40 min). All 17 studies reported a reduction in nanohardness following the erosive challenge, 4 studies investigated effect of different remineralizing agents on haltering progression of tooth erosion with varying results. Variables such as PH of the beverage and immersion time seem to play a key role in the progression of tooth erosion.