A comparative study of x-ray diffraction and infrared absorption properties and amino-acid analysis of bovine enamel

The physico-chemical changes of inorganic and organic matrix components from the coronal, intermediate and cervical parts of developing enamel have been investigated by X-ray diffraction, i.r. absorption spectroscopy and amino acid analysis. 1. (1) The initial stages of maturation were characterized mainly by growth of the apatite crystals and the later stages by removal of imperfections or strain from the crystals without much further growth. 2. (2) Changes in the i.r. spectra between the immature and the adult enamels were observed in the region of 1650 cm −1 . Although the immature enamels showed medium absorption, the adult one showed only traces of the band. 3. (3) The proportion of arginine, lysine and NH 3 increased in the highly mineralized cuspal parts and glycine, proline, glutamic acid and leucine showed a high value in the cervical parts of the enamel. Hydroxyproline was absent from bovine enamel. The changes in amino-acid composition during enamel maturation are consistent with the removal of organic matrix in the enamel.