Incorporation of 140-lanthanum into bones, teeth and hydroxyapatite

The incorporation of lanthanum in the form of 140-lanthanum onto the surface of teeth, bone and synthetic hydroxyapatite was investigated. A small amount of lanthanum was taken up by the surface of all of the materials studied regardless of their origin. The depth of penetration into bone and teeth was dependent upon lanthanum concentration and time of incubation and, in these experiments, ranged from an estimated 5 to 15 microns. An exchange of lanthanum for calcium in the apatite matrix may be responsible for increased resistance of the hard tissues to acid dissolution. The effects of pH, temperature, time and concentration of the lanthanum solutions on this incorporation were investigated. Possible clinical uses of this effect are discussed.