Origin and Evolution of Cementum as Tooth Attachment Complex

Cementum is deposited not only on the surface of the root but also on the tooth crown as coronal cementum in mammals. When the coronal cementum develops, the enamel surface is absorbed by dental follicle tissue in horses etc., the enamel development is partially inhibited and forms a rugged surface in elephants etc., and enamel reduction is seen in Berardius (tooth whale). The ivory (lateral incisor) of the elephant and the tusk of the walrus (Odobenus) are covered in thick cementum; this is a root cellular cementum with rhythmic incremental lines, because the top of it has thin enamel.