The effect of acid etching on the cervical region of the buccal surface of the human premolar, with special reference to direct bonding techniques.

Etching action on the cervical enamel compared to the central and incisal enamel of the buccal surfaces of premolars was investigated by using the scanning electron and optical microscopes. In SEM observations, the etched cervical enamel surface showed a pitted feature with no prism delineation, regardless of the prolonged etching time and the removal of enamel surface. The etched central and incisal enamel surface showed the characteristic prism-end structure. In optical microscopic observations, the tags formed at the cervical region were shorter and less numerous than those formed at the central and incisal enamel surfaces.