User:Jelly Bean MD/Tooth development

Tooth development in humans follows a general pattern consisting of five stages.

1. Bud stage: Neuroectoderm cells migrate and induce the formation of epithelial tooth buds around the 6th week of gestation.
2. Early cap stage: The oral ectoderm, that is, the epithelial structure, will form the future enamel organ. Neuroectoderm cells will mix with mesoderm cells in order to form the neural crest mesoderm.
3. Late cap stage: The future enamel organ remains connected to the oral ectoderm by the oral lamina. A second bud for the permanent tooth forms. Cells of the enamel organ differentiate into outer and inner dental epithelia. Some cells of the neural crest mesoderm differentiate into odontoblasts.
4. Bell stage: The enamel organ continues to differentiate; the stellate reticulum and stratum intermedium layers form. The inner dental epithelium is composed of ameloblasts, which synthesize enamel. As such, the crown is formed during this stage. The cervical loop corresponds to the crown-root junction. Odontoblasts become aligned and primitive dental papilla (future pulp) is formed.
5. Root formation: The junction between the inner dental epithelium and the odontoblasts is the dentino-enamel junction. Outer and inner dental epithelia eventually disappear and the odontoblasts induce the mesenchyme to form cementoblasts and cementum. The forming tooth is found within a pocket of alveolar bone. The periodontal ligament forms between the bone and the cementum.

Deciduous, or baby, teeth remain functional until the age of five or six when odontoclasts erode their roots, allowing the permanent teeth, which develop in the same manner as baby teeth, to grow.

Category:Histology Category:Human development Category:Human anatomy Category:Teeth