牙釉质，也称为珐瑯质，是牙齿最外层的组织，为哺乳动物体内最坚硬的组织，成熟的牙釉质96-99％由无机物（主要为钙和磷）组成，其他为水及有机物。

牙釉质内部并不具神经与血管。它的功用除了咬碎食物之外，也可以保护下层的牙本质，但它不会再生，因此当有蛀洞产生后不像哺乳动物的其他组织会自行修复。

Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, cementum, and dental pulp. It is a very hard, white to off white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink.