Some studies show that a coral implanted on bone tissue is gradually transformed to become a neoformed bone. In our work, we have, for the first time, determined quantitatively by NAA the transformation of a coral used as a biomaterial implanted ''in vivo'' in some ovine jaw-bones. Each month and during 9 months, biopsies were extracted. For neutron production, the nuclear reaction Be-9(d, n)B-10 was used with 17.5 MeV energy deuterons- The neutrons had a mean energy of 7 McV and a flux of 10(12) n CM-2 S-1. The radioactivation generated permitted concentration measurements of Ca, P, Mg, Sr and F in each part of the biopsies and a study of mineral transformations versus time in the coral implanted. Three months after implantation, Ca belonging to CaCO3 represented 11 % and Ca provided by the apatite formed represented 20% of the total mass. These quantitative evaluations clearly showed that five months after implantation, the coral had become a neo-formed bone.
