Advantage Arrest and fluoride varnishes that are applied once every six months or so are not notable factors when calculating fluorosis risk.  Fluoride varnishes caused fluoride blood plasma levels about the same as brushing your teeth with regular toothpaste, and Advantage Arrest has 1/10th the amount of Fluoride of a fluoride varnish application.  In short, it will be almost immeasurable.  Daily use of F products and ingestion of fluoridated water will be the notable factors that determine fluorosis.