XYLTF Using xylitol right before bedtime, after brushing and flossing, protects and heals the teeth and gums. Unlike sugar, it can even be left on the teeth overnight. With proper use, xylitol actually stops the fermentation process leading to tooth decay. Long-term use suppresses the most harmful strains of oral bacteria, making a long-lasting change in those bacterial communities. Xylitol even has the ability to enhance the mineralization of the enamel. It is most effective in treating small decay spots. Although larger cavities won’t go away, they can harden and become less sensitive.