Human tooth development to the tooth decreases with age. The enamel organ is devoid of blood vessels because of its epithelial origin, and the mineralized tissues of enamel and dentin do not need nutrients from the blood. Tooth eruption occurs when the teeth enter the mouth and become visible. Although researchers agree that tooth eruption is a complex process, there is little agreement on the identity of the mechanism that controls eruption. Some commonly held theories that have been disproven over time include: (1) the tooth is pushed upward into the mouth by the growth of the tooth's root, (2) the tooth is
Human tooth otherwise preventing crowding and/or spacing. If a primary tooth is extracted before its succeeding permanent tooth's root reaches ⅓ of its total growth, the eruption of the permanent tooth will be delayed. Conversely, if the roots of the permanent tooth are more than ⅔ complete, the eruption of the permanent tooth will be accelerated. Between ⅓ and ⅔, it is unknown exactly what will occur to the speed of eruption. Some systemic disorders which may result in hyperdontia include Apert syndrome, cleidocranial dysostosis, Crouzon syndrome, Ehlers–Danlos syndrome, Gardner's syndrome, and Sturge–Weber syndrome. Some systemic disorders which may result in hypodontia