[Fluoride content in superficial enamel layers of deciduous and permanent teeth--an in vitro study]

Enamel exhibits the highest degree of mineralization and is the hardest among tissues. Its non-organic material content is 96-98%, out of which 90% is in the form of hydroxyapatite crystals. Exchange of ions is an important property of hydroxyapatite with the hydroxyl ion (OH-) exchanging particularly easily for the fluoride ion (F-). F- ions are capable of stabilizing the structure of hydroxyapatite by reducing its solubility and in consequence increasing enamel resistance to caries. The aim of this work was to compare the content of fluoride in superficial layers of enamel obtained from permanent and deciduous teeth.

We collected 55 human permanent and 11 deciduous teeth without any evident damage to or discoloration of the enamel. Microsamples of enamel from the paragingival part on the buccal surface of the tooth were obtained using acid biopsy. Fluoride content was determined using an ion-selective electrode. Calcium content was measured with atomic absorption spectrometry.

We found that enamel of deciduous teeth is more susceptible to acid digestion than in the case of permanent teeth, although the difference was not statistically significant. The content of fluoride decreased with increasing depth of digestion. Deciduous teeth contained significantly less fluoride in every layer studied in comparison with permanent teeth.