Etching the surface of the tooth, also called conditioning, is accomplished by using 38% phosphoric acid. The acid use in etching the tooth has the additional benefit of killing the bacteria in the pit and fissures. This acid is available in liquid and gel. If you choose to use a gel, it is important to use a gel product that is specifically designed for pit and fissure sealants. Other gels may be too viscous and will not flow properly into the pits and fissures. The etching time is approximately 20 seconds for both primary and permanent teeth (Figures 10 and 11 below illustrate the placement of acid on the tooth surface).
Etching is not necessary with the glass-ionomer products, a surface conditioner may be used if desired.