FLUORINE IN DENTIN AND ENAMEL OF SOUND AND CARIOUS HUMAN TEETH

¹ Dental Research Section, Experimental Biology and Medicine Institute, National Institute of Health, Bethesda, Md.

The fluorine content of human dentin and enamel has been studied by the analyses of teeth obtained from thirty-three individuals (studied separately) and from two groups of fourteen and forty-four individuals each. The crowns of 262 sound and 248 various teeth were separated into dentin and enamel and a little over 600 fluorine determinations made on pooled or individual dentin and enamel samples. None of the teeth showed macroscopic fluorosis and, with the exception of the group of forty-four individuals, there was no reason to suspect any unusual fluoride exposure. The ash in enamel averaged 95.8 per cent; in dentin, 79.8 per cent; and no differences were apparent between sound and carious teeth. The fluorine in enamel averaged .0100 per cent and in dentin .0233 per cent, and the differences between the enamel and the dentin of sound and various teeth were not significant. Fluorine in the ash of enamel averaged .0104 per cent and in the ash of dentin, .0292 per cent. Differences between results for sound and various teeth were not significant. A study of the teeth according to anatomic or functional type also did not reveal any significant differences in fluorine content.

An evaluation of the analytical data at present suggests that fluorine data for the individual teeth of a single dentition cannot be expected, as a general rule, to show consistently less fluorine in the enamel of the various teeth than in the enamel of the sound teeth. In some individuals, fluorine in the enamel of the sound teeth alone may differ as much as the fluorine in enamel of sound versus various teeth.

There is reason to believe that an unusual dietary (particularly water-fluoride) exposure during formative tooth life may increase the fluorine content of the entire dentition, including both dentin and enamel. An increase in fluorine in all the teeth may then account for an over-all reduction in the dental caries experience. Under this circumstance it may be said that an optimum quantity of fluorine in the dentin and the enamel of the entire dentition is associated with a reduced incidence of dental caries. At the present time, data are not available to demonstrate this later hypothesis, but such an investigation is under way.