What's inside a tooth?

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The following information comes from the website of the American Association of Endodontics.

From the outside, a tooth looks like a hard, solid substance. But this cut-away illustration reveals that a tooth is really a complex system of specialized tissues.

• Enamel - the shiny, hard, white tissue covering the tooth is the strongest tissue in your body. It has to be! Your jaws place as much as 128 pounds of pressure on your teeth when you chew, bite, clench, or grind.
• Dentin - this tissue makes up most of the body of the tooth. Even though dentin is hard and feels solid to the touch, it's actually microscopically porous and needs a covering of enamel or an artificial crown to protect it from decay-causing bacteria in your saliva.
• Pulp - this soft tissue contains blood vessels, nerves, and connective tissue. The pulp provides nourishment for the tooth during growth and development. Once the tooth is mature, the pulp's only function is sensory. A fully developed tooth can survive without the pulp. If this tissue is damaged, your dentist or endodontist can remove it and save your tooth with endodontic (root canal) treatment.
• Crown - this is the part of the tooth you can see above the gumline.
• Root - this part of the tooth sits in the bone below the gum. Believe it or not, the root of your tooth is usually twice as long as the crown, the part you see above the gumline.
• Bone - the roots of your teeth are anchored by bone. Healthy teeth stimulate and keep bone tissue healthy and vice versa.
• Periodontal ligament - like the springs that hold a trampoline to its frame, this tissue supports the tooth and holds it in place in the bony socket surrounding the tooth. This tissue cushions both the tooth and the surrounding bone against the shock of chewing and biting.
• Gum - dentists call this the "gingiva." It covers the bone surrounding your teeth. When you brush your teeth after meals and floss daily, you keep this tissue healthy. That's important, because gum disease can cause bone loss. Gum disease can also expose the tooth roots to decay. If root decay affects the pulp, you may need root canal treatment.