Tooth enamel with water and organic material composing the rest. The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth develops within the gum before it erupts into the mouth. Once fully formed, enamel does not contain blood vessels or nerves. Remineralisation of teeth can repair damage to the tooth to a certain degree but damage beyond that cannot be repaired by the body. The maintenance and repair of human tooth enamel is one of the primary concerns of dentistry. In humans, enamel varies in thickness over the surface of the tooth,
Tooth whitening filling the root canal with gutta-percha points, cleaning the inside of the canal using etchant and placing a peroxide gel or sodium perborate tetrahydrate into the pulp chamber so they can work directly inside the tooth on the dentine layer. In this variation of whitening the whitening agent is sealed within the tooth over a period of some days and replaced as needed, the so-called "walking bleach" technique.. A seal should be placed over the root filling material to minimise microleakage. There is a small risk of external resorption. An alternative to the walking bleach procedure is the inside-out bleach