Bone and enamel start with the same calcium-phosphate crystal building material but end up quite different in structure and physical properties. The difference in bone and enamel microstructure is attributed to a key protein in enamel that molds crystals into strands thousands of times longer and much stronger than those in bone. The dimension of an enamel strand is 100,000 by 50 by 25 nanometers; bone is 35 by 25 by 4 nanometers.
