Cariogenicity of Acidic and Basic High-Sucrose Diets Fed Albino Rats

¹ Emory University School of Dentistry, Atlanta, Georgia

Albino rats fed a high-sucrose diet to which 1.5 per cent Na₂CO₃ had been added developed the same amount of caries as did their controls, fed the unsupplemented cariogenic diet. The pH of the two diets was 6.9 and 6.0, respectively.

The addition of 3.0 per cent Na₂CO₃ to the diet reduced the caries scores significantly, while the addition of 1.4 per cent lactic acid increased the caries score. This increase, however, was not statistically significant. The pH of the basic diet was elevated to 8.9 by the addition of the Na₂CO₃, and that of the acidic diet was decreased to 4.7. The pH on the tooth surfaces was 6.7, 7.3, and 6.3 in the rats fed the control, basic, and acidic diets, respectively.

Intubation of acid or base did not affect the caries scores, indicating that the cariostatic action of the basic diet was a local, rather than a systemic, one.

The cariostatic action of Na₂CO₃ in the diet may have two possible mechanisms: (1) maintenance of alkalinity on the tooth surface and (2) a solubilizing effect on the relatively insoluble phosphates in the diet.