You are so right for bringing this topic up! Unfortunately, if you can "taste" the toothpaste, you can also absorb every ingredient of the toothpaste, including the Fluoride. Therefore, it is impossible to use Fluoride toothpaste without absorbing at least some of it systemicallly.

There was an interesting study posted on the Fluoride Action Network site that showed your overall metabolism slows down immediately after using Fluoride toothpaste, due to your body needing to prioritize the removal of said fluoride. Interesting stuff, indeed.