Relationship of Sialic Acid to Dental Caries

¹ Division of Dental Health, Tennessee Department of Public Health, Nashville, Tennessee

Fifty-eight male volunteers, ages 16 and 17 years, who attended the Chapel Hill High School, were studied for dental caries experience (as measured by the DMF Index) and sialic acid (N-acetylneuraminic acid) content of the saliva samples as measured by the thiobarbituric acid assay of Warren.⁹ The pH (measured potentiometrically) and buffering capacity were studied according to Deakins et al.⁸ to ascertain the effect of sialic acid on the general acid picture of the saliva.

The prebreakfast and postbreakfast N-acetylneuraminic acid distributions showed that individuals in general have an increase in NANA levels within 2 to 3 hours postprandially.

Individuals also tend to have higher pH readings 2 to 3 hours postprandially, but buffering capacity values are as likely to decrease as they are to increase.

When scatter diagrams were plotted for total NANA against pH and total NANA against buffering capacity for both prebreakfast and postbreakfast saliva samples, all the correlation coefficients (r) were negative. Moreover, these relationships were stronger in the postbreakfast saliva samples.

There is no evidence in this study to support the hypothesis that sialic acid (NANA) and dental caries are related.

No association between pH and dental caries was demonstrable.

The association of buffering capacity and dental caries was a weak relationship, although it was stronger than the association of dental caries and NANA.

To the extent that sialic acid (NANA) acts biochemically as a chelating agent, the evidence derived from this investigation does not support the proteolysis-chelation theory of dental caries.