ADA approved paste
Any over the counter Fluoride
toothpaste approved by the ada should be both gentle and effective when used 2 to 3 times a day.
I would recommend the simplest Fluoride toothpaste without a lot of extra ingredients. Some of the newer toothpastes such as crest prohealth contain so many ingredients that can irritate sensitive patients. Just use a name brand simple Fluoride toothpaste.