The effect of acid etching on enamel, dentin, and the inner surface of the resin restoration: a scanning electron microscopic investigation.

Buccal cavities were prepared in vivo on 22 contralateral tooth pairs. The cavities and the surrounding enamel were either etched or cleaned with a surface-active solution (the control). The cavities were filled with Concise Enamel Bond and composite or left unrestored. The teeth were extracted immediately after treatment. Treated surfaces or the inner surface of the restorations were studied in the scanning electron microscope (SEM). An "in-pair" evaluation of the results of 320 photographs was done. The etched axial wall had a smooth surface with widened and patent dentinal tubule apertures. The corresponding inner resin surfaces were irregular, sporadically showing tags of varying length corresponding to the dentinal tubules and alternating with pits of varying size. Etching for 15 seconds or two minutes gave no apparent difference in appearance of enamel, dentin, and inner surface of the restoration.