Human tooth development the cells of the IEE secrete an organic matrix against the dentin. This matrix immediately mineralizes and becomes the initial layer of the tooth's enamel. Outside the dentin are the newly formed ameloblasts in response to the formation of dentin, which are cells that continue the process of enamel formation; therefore, enamel formation moves outwards, adding new material to the outer surface of the developing tooth. Enamel formation is called amelogenesis and occurs in the crown stage (advanced bell stage) of tooth development. "Reciprocal induction" governs the relationship between the formation of dentin and enamel; dentin formation must always occur
Tooth decay includes dental fluorosis and developmental defects of the tooth including hypomineralization of the tooth and hypoplasia of the tooth. The early carious lesion is characterized by demineralization of the tooth surface, altering the tooth's optical properties. Technology utilizing laser speckle image (LSI) techniques may provide a diagnostic aid to detect early carious lesions. Caries can be classified by location, etiology, rate of progression, and affected hard tissues. These forms of classification can be used to characterize a particular case of tooth decay in order to more accurately represent the condition to others and also indicate the severity of tooth destruction.