Tooth Enamel Structure and Composition

Enamel Characteristics

• Enamel is the only ectodermal derivative of the tooth.
• It is the hardest calcified tissue in the human body, with high mineralization.
• Enamel forms a protective covering of the tooth crown to resist stress during mastication.

Composition and Structure

• Enamel does not contain vessels and nerves.
• It is the only hard tissue that does not have collagen in its organic matrix.
• Enamel is translucent, with a color range from yellowish white to grayish white.
• Its inorganic constituents account for 96% by weight, mainly calcium phosphate in the form of hydroxyapatite crystals.

Physical Properties

• Enamel is brittle with low tensile strength, similar to ceramics.
• Its thickness varies, with maximum thickness on the cusps of molars and premolars, and thinning to almost a knife edge at the neck of the tooth.
• Enamel is thicker on the lingual surfaces of maxillary molars and on the buccal surfaces of mandibular molars.

Functional Properties

• Enamel acts as a semipermeable membrane due to the presence of cracks and microscopic spaces on the surface.
• This allows for complete or partial penetration of some fluids, bacteria, and other products of the oral cavity.