Ultra fine. Bringing smiles to life. New. Dr. Collins Perio Extreme is a brand new toothbrush that is softer and finer than the original Per Toothbrush. The Perio Extreme features ultra-fine polyester bristles which are less porous than ordinary nylon to minimize bacterial growth. The bristles are treated with a patented tapering technique which produces an extreme ultra-soft, ultra slim finish, allowing further penetration between teeth while delivering a stimulating gentle gum massage. Great for those with sensitive teeth, gum recession, root exposure, braces, or recovering from gum surgery. Also try Perio Floss part of the new Dr. Collins line of Perio products. www.drcollins.com. Made in Korea.