As the inorganic constituents of skeletons, dentine and the enamel of teeth in all vertebrates, as well as antlers of male deer, calcium orthophosphates (CaPO4) appear to be the key materials to sustain all life on Earth. Therefore, biologically relevant CaPO4 possess all the necessary features of the biomaterials, such as biocompatibility, bioactivity, bioresorbability, osteoconductivity, osteoinductivity, and appear to be non-toxic, non-inflammatory and non-immunogenic. In this book, the author presents current state-of-the-art applications of CaPO4 as bioceramics, deposits (coatings, films and layers) and in dentistry. Topics discussed include chemical composition and preparation, forming and shaping, sintering and firing for CaPO4-based bioceramics, chemical composition and preparation, pre- and post-deposition treatments for CaPO4-based deposits, followed by the detailed description of their major properties, biomedical applications and in vivo behavior. The detailed description of current CaPO4 applications in dentistry both for dental caries prevention and as various types of dental treatments is given in the last section of this book.