Tooth root: The lower two-thirds of a tooth. The roots are normally buried in bone, and they serve to anchor the tooth in position. The roots are covered with a thin layer of bone, and they are inserted into sockets in the bone of the jaw. SLIDESHOW Mouth Problems: TMJ, Canker Sores, Painful Gums and More See Slideshow From Oral Health Resources Can Oral Hygiene Curb Blood Sugar Spikes?Bad Breath: See How to Stop ItNatural Ways to Whiten Your Teeth Featured Centers Good and Bad Foods for PsoriasisVideo: Getting Personal on Life With MS Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19