Nuclear analytical methods in calcified tissue research.

Various nuclear analytical methods have been developed and applied to determine the elemental composition of calcified tissues (teeth and bones). Fluorine was determined by prompt gamma-activation analysis through the 19F(rho, alpha, gamma)16O reaction. Carbon was measured by activation analysis with 3He ions, and the technique of proton-induced x-ray emission (PIXE) was applied to simultaneously determine calcium, phosphorus, and trace elements in well-documented teeth. Dental hard tissues (enamel, dentine, cementum, and their junctions) and different parts of the same tissue were examined separately. With the use of a proton microprobe, we measured the surface distribution of fluorine and other elements on and around carious lesions on the enamel. The depth profiles of fluorine, and other elements were also measured right up to the amelodentin junction. We discuss the development of various nuclear techniques and their applications, mainly in the field of dental health and to some extent in the study of the role of lead in mental retardation. We do not mention other important areas of calcified tissue research where these techniques could play an important role (e.g., in accurate and nondestructive measurements of calcium, phosphorus, and other elements in small bone biopsies taken from patients with metabolic bone disorders). No suitable chemical method appears to be available that can provide accurate assessment of calcium, phosphorus, and other trace elements in small bone biopsies. Moreover, the nondestructive nature of the nuclear methods has an extra advantage in that the bone samples, which are normally rather small in quantity, subsequently can be used for histologic examination.