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 cause of tooth impaction is lack of space in the mouth for the tooth. Other causes may be tumors, cysts, trauma, and thickened bone or soft tissue. Tooth ankylosis occurs when the tooth has already erupted into the mouth but the cementum or dentin has fused with the alveolar bone. This may cause a person to retain their primary tooth instead of having it replaced by a permanent one. A technique for altering the natural progression of eruption is employed by orthodontists who wish to delay or speed up the eruption of certain teeth for reasons of space maintenance or