HUMAN SALIVA

II. A TECHNICAL PROCEDURE FOR CALCIUM ANALYSIS

¹ George Williams Hooper Foundation for Medical Research, and College of Dentistry, University of California, San Francisco, Calif.

1. A recent survey of international literature revealed the inadequacy of present knowledge of salivary-Ca content. The wide range of results was shown to be due in part to the methods employed for Ca analysis; in part, to the basis on which subjects were selected for examination.

2. In order to establish a standard procedure for salivary analysis, the methods of Ca determination, as used on biological material, were reviewed and modifications of the procedures of Halverson and Bergeim, and Kirk and Schmidt, were developed and found to be most suitable.

3. Previous tests of preliminary treatment showed the necessity for deproteinization. Recent work has indicated that the saliva should also be centrifuged.

4. The author tested different types of saliva from ten subjects for the influence of preliminary centrifugation. In six no effect was found, disaffirming the observation of Clark and Levine that there was a "consistent" loss of Ca in centrifuged samples.

5. The original data of Clark and Levine showed that this observation was not true of all single determinations, but only of certain averages. Thus the results of Clark and Levine, Becks and Wainwright, and the author, agree in proving that the lower values in centrifuged samples, as compared with uncentrifuged ones, occur only occasionally and always irregularly.

6. Preliminary centrifugation is recommended for a standard method because irregularly low results are apparently due to inclusion of Ca-containing debris.

7. Known amounts of Ca, added to saliva samples, were satisfactorily recovered. These findings demonstrate clearly the accuracy of the recommended procedures, and furnish the conclusive evidence required for their adoption.

8. Detailed descriptions are given of the technical procedures for salivary-Ca determination, according to modifications of the methods of Halverson and Bergeim, and Kirk and Schmidt.