Answer
Dentin is the material that is the main component of teeth. It is a kind of calcified connective tissue that is very hard because it contains 70% hydroxyapatite--bone has just 55% hydroxyapatite
Work Step by Step
Hydroxyapatite more accurately calciumhydroxyapatite has the general formula Ca5(PO4)3(OH).
Dentin is harder than bone, but in teeth, dentin is covered by enamel which is 95% calcium salts. Thus enamel is the hardest substance in the body. The dentin that surrounds the root of the teeth goes by the special name of crementum.
