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

https://www.mediafire.com/file/mhab3zj7f7c5ik0/pdf-59830-29989.pdf/file

Fluoride varnish or remineralizing pastes can be used after whitening to enhance enamel and minimize level of sensitivity while preserving your brighter smile.