Experiments were conducted on the incisor of young rats to show (1) the precise areas and manner in which the tetracycline fluorophore combines with dentin and enamel and (2) the relation between the tetracycline localization and mineralization. For the objectives mentioned above rats were injected with tetracycline and a combination of tetracycline and Ca45. Detailed examination of the teeth of specimens injected with tetracycline show a rapid uptake and localization of fluorophore in areas undergoing mineralization. Areas adjacent to the increments undergoing mineralization also reveal the presence of the fluorophore, but to a lesser extent. Comparison of the same area of the tooth injected with tetracycline and Ca45 show that the fluorophore is localized exclusively in areas undergoing mineralization, and to a lesser extent in adjacent, incompletely mineralized regions.
Despite the fact that our observations have demonstrated the avidity tetracycline exhibits for mineralizing and recently mineralized areas of dentin and enamel, we have not been able to exclude the possibility that the fluorophore may combine with the organic matrix of these tissues as well as the mineral component.