A bacteria cell has an outer layer called cytoplasm. This portion of the cell surrounds a spaghetti pile of DNA called a nucleoid.
When products containing sugar or carbohydrates are consumed, sugar will dissolve in saliva and be absorbed by bacteria in plaque on teeth. The sugar is absorbed into the cytoplasm layer and then is transported to “feed” the cell with energy to reproduce and multiply.

Xylitol is readily absorbed by plaque bacteria, where it travels into the cell cytoplasm. The difference is that the cell lacks the mechanism to provide energy for the cell to multiply and reproduce. Furthermore the cell tries to expel the Xylitol, and expends energy trying to push the Xylitol away and out of the cell.
Because the bacteria cell uses its energy to expel the Xylitol, it is less able to stick to teeth and is therefore more easily removed by tooth cleaning. Xylitol has also interfered with acid production by the cell and prevented reproduction. This process of using energy to no purpose is called a futile cycle.

Toxic, cavity forming plaque bacteria die each time they are in contact with Xylitol. As harmful bacteria are cleaned away, new Xylitol-resistant bacteria take their place. These new bacteria do not produce acids, do not damage teeth and do not form sticky layers of plaque. These bacteria appear to form a protective coating over teeth – fighting off intruding bacteria and protecting enamel from things that may harm teeth.