Anatomy
Enamel
Enamel is the hard, mineral-rich outer layer of the crown of a tooth. It covers the dentin underneath and protects the tooth from daily chewing, heat, cold and acids.
Enamel is the outer shell of the visible part of your tooth. It is the hardest tissue in the body. It has no living cells, so the body cannot grow it back once it is lost.
Enamel protects the softer dentin and the tooth pulp underneath. Acids from bacteria in dental plaque can wear enamel down. That is how a cavity starts. Fluoride, from toothpaste and from some drinking water, helps enamel resist those acids.
When enamel wears thin, teeth can feel sensitive to hot, cold or sweet foods. Only a dentist can repair damage to a tooth. Ask your dentist what you can do to protect the enamel you have.