The tooth bud soon becomes invaginated through proliferation of the underlying mesenchyme. This is called the dental papilla, from which dental pulp and dentin arise. The cap-shaped organ coming from the ectoderm is called the enamel organ because it produces the enamel. It consists of external and internal enamel epithelia, which enclose the enamel pulp. The enamel organ is free from blood vessels and instead is supplied by vessels reaching the external enamel epithelium. The local mesenchyme around the enamel organ condenses and forms the dental sac. The latter gives rise to the periodontium and to the cementum of the tooth root.
The margins of the enamel organ grow more strongly than the middle part. Therefore, the tooth bud undergoes a cap phase before becoming the tooth bell. The mesenchymal cells of the dental papilla bordering the internal enamel epithelium differentiate into odontoblasts, which secrete predentin. The predentin transforms into dentin through calcification. The cells of the internal enamel epithelium differentiate into ameloblasts or adamantoblasts. These produce enamel prisms that connect to the dentin. The crown part of the enamel organ disappears and so only a cell-free enamel cuticle remains.
The definitive tooth is comprised of the crown, which overgrows the gums, the neck, which surpasses the border of the alveolar compartment but is still covered by the gums, and the root, which anchors in the bony alveolar compartment of the jaw.