Sodium fluoride is a chemical that is added in many municipal water supplies to prevent tooth decay. You can even find it in your toothpaste if you look at the ingredients. Sodium fluoride is a very safe and effective chemical used in lots of oral products because of its benefits against tooth decay. Hope this helps!
Endocytosis and exocytosis are similar in that they are both forms of cell transport. They differ because in endocytosis, a cell transports molecules into a cell (think: endo - in), and in exocytosis, the cell's molecules are transported by being expelled.