THE PROTECTION OF THE WET ENAMEL SURFACE BY ADSORBED FILMS

¹ University of Otago Dental School, Dunedin, New Zealand

1. The investigation of the role of surface-active agents in inhibiting enamel decalcification has been extended to include 5 high molecular weight amines and other polar compounds.

2. The power to protect the intact enamel surface against acid was found only in the amines and was exerted from either aqueous or oily solution.

3. In the homologous series of primary aliphatic amines, the protective effect rises to a sharp maximum with tetradecylamine, C₁₄ H₂₉ NH₂. Under the conditions of our experiment, a 1 per cent solution of this amine in medicinal paraffin produced a degree of protection of 86 per cent. The protective effect was enhanced by thorough cleansing of the tooth surface before wetting with saliva.

4. Amines which have the ability to protect the intact enamel surface produce a parallel effect on powdered calcium phosphate by retarding its dissolution in acid to approximately the same extent. This demonstrates that amines protect the enamel by virtue of their affinity for its inorganic constituents.

5. The most suitable agent for a clinical investigation appears to be a solution of tetradecylamine in medicinal paraffin oil.