• DOI:10.1177/00220345450240050301
• Corpus ID: 11624798

The Effect of Sodium Fluoride on the Solubility of Calcium Phosphate, Tooth Enamel and Whole Teeth in Lactic Acid

@article{Rae1945TheEO,
  title={The Effect of Sodium Fluoride on the Solubility of Calcium Phosphate, Tooth Enamel and Whole Teeth in Lactic Acid},
  author={James Jamieson Rae and Charles T. Clegg},
  journal={Journal of Dental Research},
  year={1945},
  volume={24},
  pages={235 - 237}
}

• J. Rae, Charles T. Clegg
• Published 1 October 1945
• Materials Science
• Journal of Dental Research

When whole teeth were suspended in 1% lactic acid solutions, buffered with potassium hydrogen phthalate and adjusted to a pH of about 3.6, marked decalcification occurred in 24 hours at 37°. No decalcification was apparent, however, when sodium fluoride was added under the same conditions in concentrations varying from 0.2 to 0.5%. Tooth enamel was prepared according to the method of Manly and Hodge (2) and this material was used in an attempt to overcome individual variations in teeth. On shaking purified powdered tooth enamel with: (a) 1% buffered lactic acid and (b) 1% buffered lactic acid to which 0.5% sodium fluoride had been added, both at pH 3.5, a marked difference in the weights of residue left in the tubes after 24 hours was observed and these weights showed no appreciable difference after an additional 24 hours shaking. The addition of a similar amount of sodium chloride had only a very slight-effect on the decrease in the weight of the residue. Determinations of inorganic phosphate on the supernatant liquids were made calorimetrically by means of King's method (3). The results of this experiment are shown in Table I. These phosphate values would indicate that even though the sodium fluoride decreases the apparent solubility of tooth enamel (as shown by the differences in decrease in weight of residue) the enamel is being dissolved, as indicated by the phosphate values, to the same or to even a greater extent in the tubes containing fluoride. This experiment was repeated, substituting pure tri-calcium phosphate in place of the tooth enamel, in view of the fact that powdered tooth enamel is a very complex substance. The results obtained (Table II) were entirely analogous to those described above, viz., the addition of sodium fluoride decreased the apparent solubility of calcium phosphate to about one-third of its solubility in 1% lactic acid; while at the same time the inorganic phosphate in the supernatants of all tubes rose to approximately the same values. The wide differences in calcium values would indicate that the decrease in the weight of the residue