Possible Relationship Between the Fluorine Content of Enamel and Resistance to Dental Caries

Abstract

of Minnesota, Minneapolis That the susceptibility and immunity of teeth to caries is to be accounted for, at least in part, by differences in composition is a hypothesis that has long been attractive. The evidence for the claims (7, 8) that such differences exist have failed of confirmation. We (3) found enamel and dentin fractions prepared from sound and carious teeth to possess compositions, with respect to the calcium, phosphorus, magnesium, and carbonate contents, which were not significantly different. LeFevre and Hodge (9) found whole tooth inorganic substance prepared from carious specimens to differ from that obtained from sound teeth only with respect to a slightly higher moisture content of carious tooth substance.2 Without regard to the data to be presented below, there is evidence that marked changes in some of the properties of enamel accompany changes in its fluorine content. The amount of fluorine in mottled enamel is relatively slight (4) in comparison to the total inorganic material; yet it produces, or is accompanied by, profound changes in the appearance and properties of the enamel. In this connection it is worthy of mention that it has not been demonstrated that mottling of enamel is due entirely to the effect of fluorine combined in the inorganic phase and is possible that the condition is produced, in part, by the operation of the fluoride ion on enzymes during the calcification of the enamel. The effect of fluorine added to the diet on the quality of the teeth of rats first observed by Schulz and Lamp (13) and independently (10) has since been noted by numerous workers. The hardness of the incisor teeth, which in the rat grow continuously throughout life, is augmented by increasing, within certain limits, the amount of fluorine in the diet so that they are not worn at the usual rate and therefore become much longer than those of normally fed animals. Such teeth may be regarded as possessing some superior qualities even though they may not be adapted to an efficient use by the rat and in spite of the fact that the calcification of the enamel and dentin may be abnormal. Armstrong (1) fed an adequate diet to rats to which was added during alternate three week periods 0.1 per cent sodium fluoride. Alternating transverse bands of mottled and normal enamel were thus produced across the incisor teeth. These teeth after attaining a considerably increased length frequently fractured, but the fracture line was usually transversely situated through a band of normal enamel. It thus appears that the hardness and strength of the incisor teeth of rats is improved by a moderately increased fluorine content of the mineral phase or by some change produced in the structure of the tooth which occurs during the formation of the enamel and dentin under the influence of a higher than normal concentration of fluorine.The literature (11) contains occasional statements to the effect that moderately mottled human teeth are apparently more resistant to caries than normal teeth. Every dental clinician interviewed by u...

The Relationship between Fluoride Concentration and the Caries Frequency of Different Tooth Surfaces in a High Fluoride Area

“…This hy pothesis had been suggested by two groups of observations: (1) according to some authors [Armstrong, 1938;Bibby and V an Kestern, 1940;Po lice, 1960;Benagiano, Moschella and Sacca, 1962, in contrast with McClure, 1956 andT empestini, 1966] sound enamel from sound teeth contains more fluoride than sound enamel from carious teeth; (2) accord ing to Backer D irks [1963,1967], the effect of fluoridation in reducing dental caries is not the same for different surfaces of the tooth; in the Tiel-Culemborg experiment the caries protective action of fluoride, ex pressed as percentage reduction in caries, was found by Backer D irks to be greater on the approximal, buccal and lingual surfaces than on the oc clusal surfaces, and greater on the incisors than on the posterior teeth. In an earlier investigation Marci and Scavizzi [1967] examined, in a clini cal caries study, the teeth of residents of a low fluoride area (Rieti).…”

The Effect of Fluorine on Mouth Bacteria

“…of fluorine in enamel and dentin respectively (14), have a greatly enhanced resistance to caries, concentrations of fluorine between 1 and 400 p.p.m. should produce any of the effects on bacteria which might be responsible for the reduced activity of caries.…”

Systemic versus Topical Fluoride

“…While some could demonstrate that the solubility of enamel originating from residents of a fluoridated region was low, the others could not confirm these results and no direct correlation between fluorapatite in enamel and caries levels in populations could be demonstrated [Armstrong and Brekhus, 1938;Mellberg and Ripa, 1983]. Moreover, it was reported that even shortly after eruption the surface enamel is partly abraded physiologically and fluoride-rich enamel is lost [Aasenden, 1975].…”