With years of using it the product is really effective. My teeth before goes a little yellowish due to coffee and tea smudges while on my husband its due to his smoking bliss. It can’t be remove by ordinary toothpaste so we tried this toothpaste with fluoride. We usually apply it after our regular brushing with the ordinary toothpaste three times a day. Not only on teeth but also on tongue you can see the positive changes gradually. After brushing with FAST you can feel the cleanliness of your mouth even when you grind your teeth or even look at your tongue in the mirror, it really works. And the flavors are really cool, it comes in original, citrus and cool mint. The cost is just 20-30% higher than our regular tootpaste.