Phosphoric acid penetration during direct bonding

This work has investigated the actual penetration of acid etching material into the enamel surface as it is used in preparation for the direct-bonding adhesive. Three important conclusions can be drawn from this investigation. (1) Rinsing does not necessarily completely arrest the acid etching process in the depth of the exposed enamel. (2) The effect of the acid etching material does seem to be deeper than 10 mu, which is contrary to the manufacturers' statements. There is (3) no evidence of actual penetration of the acid etching material at the dentinoenamel junction.