, its range is slightly larger than the area of the base plate of the ceramic bracket, the treatment time of acid etching needs abou 60-90 seconds, and the fluorosis tooth needs 2-3 minutes.C: Rinse, dry: after etching, the tooth surface must be washed thoroughly with clean water more than 3 times, washed the acid solution and debris thoroughly, then blow dry, when the tooth surface lack of luster and chalk, the tooth surface that had been etched by acid should be strictly prevented from saliva