Once you are ready to use, you make a scored line all the way around the bark ½ inch from the end. You then nibble on the end of the exposed brush to start forming bristles. The duration in which this lasts depends on how much you brush your teeth. They typical trim on the twig brush lasts 3-5 days. I have found I can get a week out of the bristles because I always forget to take to work with me.
When the twig brush is used it forms a layer over the enamel from the Natural resin, protecting your teeth.