Teeth manage both by having two layers: a hard external cap of enamel, made up almost entirely of a calcium phosphate, and beneath it, a tougher layer of dentin, partly formed from organic fibers that make it flexible.

外层由坚硬的牙釉质包围，几乎完全由磷酸钙组成，牙釉质之下，有一层更加强韧的牙本质，部分由有机纤维组成，它们能够使牙齿强韧。