Enamel is the thin outer covering of the tooth. This tough shell is the hardest tissue in the human body. Enamel covers the crown which is the part of the tooth that's visible outside of the gums.
Because enamel is translucent, you can see light through it. But the main portion of the tooth, the dentin, is the part that's responsible for your tooth color -- whether white, off white, grey, or yellowish.
Sometimes coffee, tea, cola, red wine, fruit juices, and cigarettes stain the enamel on your teeth. Regular visits to your dentist for routine cleaning and polishing can help remove most surface stains and make sure your teeth stay healthy.
Enamel helps protect your teeth from daily use such as chewing, biting, crunching, and grinding. Although enamel is a hard protector of teeth, it can chip and crack. Enamel also insulates the teeth from potentially painful temperatures and chemicals.
Unlike a broken bone that can be repaired by the body, once a tooth chips or breaks, the damage is done forever. Because enamel has no living cells, the body cannot repair chipped or cracked enamel.