Wonseon Chae

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1. Introduction Tooth enamel is the most highly mineralized tissue in the human body. Mature enamel has a unique microstructure, with compactly packed hydroxyapatite crystallites [1]. To achieve such hard mechanical properties, highly coordinated biological processes must be well-regulated and function without errors. The assault from certain environmental and/or genetic factors can adversely affect this delicate process, resulting in pathologic findings such as enamel defects [2].