Purebrush toothbrushes have been specially designed by Murdock Laboratories to work in conjunction with your Purebrush Antibacterial Toothbrush Purifier and have been approved by the American Dental Association. Our toothbrushes have been manufactured without the use of color pigments or rubber handles that would otherwise impede the effectiveness of the UV sterilization. To insure proper cleaning and brushing with your new Purebrush toothbrushes, Murdock Laboratories and the American Dental Association both recommend that your brushes be changed every ninety (90) days. This recommendation is due to bristle break down which decreases the amount of plaque removed from around the base of your teeth and gum line. Four toothbrushes are shipped per package.