émail

Enamel, or émail in French, refers to two related but distinct substances. In dentistry, dental enamel is the hard, outer layer covering the crowns of teeth. In materials science and art, vitreous enamel (often called simply enamel) is a glassy coating fused to metal or ceramic to provide color, protection, and a smooth surface.

Dental enamel is the hardest tissue in the human body, consisting mainly of hydroxyapatite crystals arranged in enamel prisms. It is about 96 percent mineral by weight, with small amounts of water and organic material. Enamel forms during tooth development by ameloblasts and, after eruption, cannot regenerate if damaged. It protects dentin and pulp from wear, decay, and temperature changes, but is susceptible to demineralization by acids and to abrasion. Fluoride therapies promote remineralization and increase resistance to acid.

Vitreous enamel is produced by applying a ground glass frit to a substrate and firing it at high temperature until the glass fuses into a smooth, durable coating. The surface is hard, chemically resistant, and non-porous, and can be colored with metal oxides. Enamel coatings are used on cookware, sanitary ware, architectural fittings, and art objects. They can chip or crack under impact and may degrade with thermal cycling or abrasion.

Both forms of enamel are valued for their aesthetic and protective properties, but their applications and limitations differ: dental enamel is a biological tissue with limited capacity for repair, while vitreous enamel is an engineered coating designed to endure harsh environments.