Acids with an equivalent taste lead to different erosion of human dental enamel

The consumption of acidic soft drinks may lead to demineralization and softening of human dental enamel, known as dental erosion. The aims of this in vitro study were to determine: (i) if different acids with a similar sensorial acidic taste lead to different hardness loss of enamel and (ii) if the fruit acids tartaric, malic, lactic or ascorbic acid lead to less hardness loss of enamel than citric or phosphoric acid when their concentration in solution is based on an equivalent sensorial acidic taste.

Enamel samples of non-erupted human third molars were treated with acidic solutions of tartaric (TA), malic (MA), lactic (LA), ascorbic (AA), phosphoric (PA) and citric (CA) acids with a concentration that gave an equivalent sensorial acidic taste. The acidic solutions were characterized by pH value and titratable acidity. Atomic force microscopy (AFM) based nanoindentation was used to study the nano mechanical properties and scanning electron microscopy (SEM) was used to study the morphology of the treated enamel samples and the untreated control areas, respectively.

The investigated acids fell into two groups. The nano hardnesses of MA, TA and CA treated enamel samples (group I) were statistically significantly greater (p<0.05) than the nano hardnesses of PA, AA and LA treated enamel samples (group II). Within each group the nano hardness was not statistically significantly different (p>0.05). The SEM micrographs showed different etch prism morphologies depending on the acid used.

In vitro, the acids investigated led to different erosion effects on human dental enamel, despite their equivalent sensorial acidic taste. This has not been reported previously.