Fluoride varnish or remineralizing pastes can be used after whitening to strengthen enamel

https://www.animenewsnetwork.com/bbs/phpBB2/profile.php?mode=viewprofile&u=1174459

Fluoride varnish or remineralizing pastes can be used after whitening to reinforce enamel and reduce level of sensitivity while maintaining your brighter smile.