Experimental erosion of dentin.

Experimental erosion in human dentin was investigated with scanning electron microscopy. Erosion was caused by solutions containing either 0.030 mekV/g malic acid (pH 3.4), 0.034 mekV/g phosphoric acid (pH 2.6), or 0.038 mekV/g citric acid (pH 2.8). Test specimens prepared from the coronal parts of erupted third molars were immersed in the solutions from 30 s to 60 min. When compared with controls, exposure of dentin tubules was observed in all the specimens already after 30 s immersion, irrespective of the acid used. Mineral loss was seen to progress at the interface between peritubular and intertubular dentin in specimens immersed for 60 s in the acidic solutions. Longer times of immersion resulted in hollowing of the tubular openings by complete destruction of the peritubular dentin. Surface roughness and porosities were seen also at the intertubular areas. Although based on a simplified study model, our results may explain why so many patients with erosions suffer from painful sensitivity of their teeth: the acids causing erosion can expose inner dentin structures to outer stimuli by significant enlargement of the dentinal tubules.