Contralateral symmetry of acid etched enamel surfaces

Scanning electron microscopy (SEM) of phosphoric acid etched labial enamel surfaces of human permanent incisors and canines showed that the etch pattern, including the depth of the etched relief, may vary significantly from tooth to tooth and between different areas of the same tooth. On the other hand, pairs of contralateral teeth showed a very similar etch pattern symmetrically along the midline. No difference in the pattern could be found in enamel etched with three different orthophosphoric acids: 50% with 7% ZnO, 37%, and 35%. Therefore, when comparing the depth of penetration of different cold-curing restorative resins, composite or non-composite, into the etched enamel relief, it seems appropriate to study these materials two-by-two on pairs of contralateral teeth.