When we eat something, it creates acidic reactions to take place in our mouth. This leads to the decreasing of pH of the mouth and the acid becomes strong enough to corrode the enamel of our teeth. This leads to tooth decay. So, to invert the effect of the acid, tooth paste contains base so as to neutralise the effect of acid. This can be called as neutralisation reaction.
Hope this helps... all the best...,plz mark it as the best if possible..... :) ;)