Studies on mineralized dental tissues: I. A microradiographic and autoradiographic investigationof teeth and tooth germs of normal dogs

Abstract

Summary This investigation was carried out in order to get further information onthe mineralized dental tissues. Two young normal dogs were injected, one with Na 2 S 35 O 4 , the other with Ca 45 Cl 2 . From selected parts of the lower jaws thin ground sections were prepared. These sections were studied by means of a combination of autoradiographic and microradiographic techniques. The autoradiographs revealed an uptake of both Ca 45 and S 35 in essentially the same locations of the bone and tooth tissues. There was thus a high uptake of isotopes in the periosteal areas and in young osteons and certain areas of the cancellous bone. In the deciduous teeth the labelling was most pronounced along the pulpo-dentinal border. In the tooth germs there was a high uptake of both isotopes along the pulpo-dentinal border in the same area. There was also a labelling along the enamel surface. In certain tooth germs, where the microradiographs indicated a high mineralization in the cusp tips, there was a diffuse labelling throughout the whole breadth of the enamel. These findings were interpreted as an expression of a secondary mineralization. The uptake of S 35 differed in certain respects from that of Ca 45 . In the tooth germs there was thus an uptake of S 35 along the dentino-enamel junction, and in the soft tissues, especially in the pulps of the tooth germs, there was also a marked labelling of S 35 only. Further, the labelling at the pulpodentinal border showed features differing from the autoradiographs obtained with Ca 45 . Thus the uptake of S 35 at this site was concentrated in two closely adjacent bands. It was concluded that the uptake of Ca 45 took place in the mineralized constituents of the tissues. However, as regards S 35 , one part was probably incorporated in the crystal lattice of the minerals, another being deposited with the organic matrix, presumably as mucopolysaccharides containing ester sulfuric acid. This latter conclusion refers to the uptake along the pulpo-dentinal border.