The local environmental condition in our mouth are continuously changing. The longer the time that the condition is acidic, the more decalcification and the more risk of dental caries. However, the longer the time that the condition is neutral or alkaline, the more recalcification and the less risk of dental caries. Therefore, keeping the condition neutral or alkaline as long as possible is the basic policy of preventing dental caries.

After our meals, glucide remains in our mouth. Streptococcus mutans metabolizes these remains to a lot of latic acid. So after meals, the local environment conditions in our mouth is quickly changed into acidic. Because glucide is nourishment of the bacteria, sometimes it is said that sweets make dental caries. However, some types of bacteria have different amounts of acid. With sucrose that is the main ingredient of sugar, the most amount of acid is provided. The second is glucose. With xylitol, few acid is provided and xylitol helps the prevention against dental caries. However, it is not proved that xylitol promote the recalcification and xylitol itself can't cure dental caries.

At meals and snacks, keeping an appropriate amount of carbohydrates, sucrose in particular inhibits the production of acid and weakens the effect of acid in our mouth. So this is one effective way to prevent dental caries.

However, the most basic prevention of dental caries is dental cleaning. Primarily, dental cleaning has the effect of removing the remaining food in the mouth. This removes the nourishment of streptococcus mutans and reduces the amount of the acid provided by the bacteria. And Secondly, dental cleaning has the effect of plaque control. This remove the plaque and the bacteria living in it. The Reduction in the bacteria will decrease the amount of the acid.