Etchants and conditioners. The goal of etching is to
produce an uncontaminated, dry, frosted surface
[Manton and Messer, 1995]. The most frequently used
etchant is orthophosphoric acid, provided that its
concentration lies between 30% and 50% by weight.
Small variations in the concentration do not appear to
affect the quality of the etched surface [Waggoner and
Siegal, 1996]. Duggal et al. [1997] showed no
significant difference in retention of FS after one year
follow-up on second primary and first permanent
molars when 15, 30, 45 or 60 seconds etching times
were used.