Enamel is a highly mineralized cellular tissue, and it decays through a chemical process arising from the acidic environment produced by bacteria. As the bacteria consume the sugar and use it for their own energy, they produce lactic acid. The effects of this process include demineralization of crystals in the enamel, which are caused by acids, over time until the bacteria physically penetrate the dentin. Enamel rods, the basic structural unit of enamel, run vertically from the surface of the tooth into the dentin. Because enamel etching by caries generally follows the direction of the enamel rods, different triangular patterns develop between the pit, fissure, and soft tooth caries in the enamel because the orientation of the enamel rods differs in the two regions of the tooth.[74]
As the enamel loses minerals, and tooth decay progresses, the enamel develops several distinct areas, visible under a light microscope. From the deepest layer of enamel to the surface of the enamel, the delineated areas are: the zona pellucida, the opaque areas, the lesion body, and the superficial zone.[75] The zona pellucida is the first visible sign of caries and coincides with a loss of one to two percent of minerals.[76] Slight remineralization of the enamel occurs in the darkened area, which is an example of how the development of dental caries is an active process with variable changes.[77] The area of greatest demineralization and destruction is in the body of the pest itself. The surface area remains relatively mineralized and present until the loss of tooth structure leads to a cavity.
the teeth
