Enamel etching

Abstract

After the deterioration due to an acid or chelating solution, enamel crystal dissolution starts either as screw dislocations in the central part of the crystallite (dissolution of the hollow-core type), or the initial dissolution begins at defects located in the edge of the crystallite (edge dislocation). A thin layer is dissolved by the acid and eliminated near the enamel surface. In the inner prismatic zone, the rods disappeared, leaving a continuous network of interprismatic enamel (type 1 etching pattern), or the interprismatic enamel is dissolved and rods persist (type 2 etching pattern). An amorphous flat surface may be observed where rods and interrods are both dissolved (type 3 etching pattern). Using chelators, rods protrude on 20-50 µm in length, whereas interrods are dissolved. Enamel etching is due to acid corrosion, a phenomenon occurring in the absence of bacteria. Used at the chair side, this method increases resin adhesion on dental enamel and has clinical implications.