188 



ADVEXrrRES IX RADIOISOTOPE RESEARCH 



EXCHANGE OF PHOSPHORUS IN HUMAN TEETH 



Other things being equal the exchange of phosphorus in teeth will 

 be determined })y the efficiency of lymph circulation in the tooth. 

 Exchange experiments can thus be carried out to obtain information 

 on the latter point. It does not look improbable that the growth of caries 

 will be facilitated by a poor circulation; to decide this point we compared 

 the phosphorus exchange in two teeth of the same individual (16 years 

 old) removed simultaneously, one on account of caries, the other, a 

 healthy one, to space the patients teeth better; about a two hundred 

 thousandth part of the labelled phosphorus was found in each of the 

 teeth investigated, a quantity sufficient to be measured but not large 

 enough to permit the exact comparison necessary to decide the point 

 discussed above. The weights of the whole fresh teeth were 800 and 

 540 mgm and of the ash obtained on ignition 465 and 330 mgm 

 this corresponds to a loss on ignition of 58 and 61%. The time 

 which elapsed between the injection of the radioactive phosphorus 

 and the extraction of the teeth was 7 days. Through the very great 

 kindness of Professor Lawrence we were able to continue these 

 experiments using a much stronger radioactive phosphorus sample 



Table 21. 

 Labelled Phosphorus in the Teeth of a 25 Year Old Patient 



a) Necrotic Roots. 



Fresh weight 



Asli weight 



Relative labelled P content 



In total 

 root 



In 100 mgm 

 root ash 



1 



2 



3 



4 

 5 

 6 

 7 

 8 

 9 

 10 



1.96 

 2.72 

 1.97 

 0.98 

 5.13 

 2.19 

 3.86 

 1.47 

 3.57 

 1.83 



prepared by him with the aid of his powerful cyclotron. 900 mgm 

 labelled sodium phosphate per os w^ere administered to a patient 25 

 years old. 4 days later 10 necrotic teeth and 5 days later still, three 

 more, fairly well preserved, living teeth were extracted. Of the 2.5 • 10** 



