Hey beckyilmk, I assume you are referring to the Prevident 5000 Plus toothpaste. We advise our patients to use either a Fluoride rinse or toothpaste for 2 weeks prior to whitening and then continue for at least another two weeks. Sensitivity is the most common adverse side effect teeth whitening. We find that Fluoride strengthens teeth and reduces Post whitening sensitivity. We advise our patients to use Fluoride rinses or toothpaste twice a day. Swish the rinse for at least a minute or brush with the toothpaste then spit after use so that it stays on your teeth. Don’t eat or drink anything for at least 30 minutes after. Good Luck!