Tooth development results from an interaction of the oral epithelial cells and the underlying mesenchymal cells. Each developing tooth grows as an anatomically distinct unit. The fundamental developmental process is similar for all teeth. Each tooth develops through successive bud, cap, and bell stages. During these early stages, the tooth germs grow and expand, and the cells that are to form the hard tissue of the teeth then differentiate. Once this occurs in the bell stage, the stage of dentinogenesis and amelogenesis take place. After the crowns and roots of these teeth form and mineralize, the supporting tissues of teeth, cementum, periodontal ligament, and alveolar bone begin to form. The bud stage is the rounded localized growth of the epithelial cells of the enamel organ embryo bud at 11.5 days. Gradually the round epithelial bud gains a concave surface, and the enamel organ is then considered to be in the cap stage of development embryo at 12.5 and 13.5 days. After further increase in size of the enamel organ and adjacent dental papilla, the tooth germ reaches the bell stage (embryo 14.5 and 15.5 days). This is the differentiation stage, and it exhibits two characteristics, the inner enamel epithelial cells define the shape of the future tooth crown to be formed, and the inner enamel epithelial cells elongated and differentiates into ameloblasts to become the future enamel forming cells.