Changes in the pH in your mouth. Obviously the idea of increasing the concentration of minerals in your saliva favors the deposition. But how long is the effect of the toothpaste going to last, etc. IMHO toothpaste is a feel good, make your mouth taste good, make Proctor and Gamble lots of money deal. You teeth generally get just as clean brushing and flossing. As to Flouride, the addition of flouride is helpful for kids whose water supply is not fluoridated. Probably not needed otherwise. Some kids maybe are getting too much. Dentists see varying degrees of “ fluorosis” ( enamel changes due to flouride) all the time.