Continuing Evaluation Of The Use Of Fluorides

Erling Johansen

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9780429727344
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Physics
• Index: Physics

This work addresses a variety of topics that are of interest in their own right and because they bear on the evaluation of the safety of fluoridation. The latter is important because the demonstration of "no effect" from the use of fluorides is very difficult and the available data need to be periodically reexamined to reduce the theoretical amount

1
Historical Perspectives

Reidar F. Sognnaes

This state, Colorado, and this organization, the American Association for the Advancement of Science, have done much to pioneer and publish the historical developments of fluoridation. Therefore, it is quite appropriate that we meet here to observe the 60th anniversary of the discovery of the so-called "Colorado brown stain" — later to become known as mottled teeth or dental fluorosis — and to update the publications on fluoridation through the forum of AAAS; and in retrospect, we must also pay tribute to some of the early observers who had stimulated interest in the subject many years before.

Some Pre-Colorado Observations

Even before the turn of the century, according to a dental research conference held in Germany, one observer (Kühns, 1888) had reported a darkish tooth mottling in an entire family which had lived in Durango, Mexico. Better known, in retrospect, is a publication at the turn of the century by Eager (1901; 1902), who attributed the unusual darkened color of the teeth of Italian immigrants to the drinking water contaminated from some volcanic source in their place of birth and youth. Though fluoride in the drinking water was not scientifically related to mottled enamel until 1931, it was suggested more than 100 years earlier by Berzelius (1822) that the fluoride which he had been able to demonstrate in teeth was probably brought there through drinking water, in which he had demonstrated the presence of over 1 part per million of fluoride. Before Berzelius, the demonstration of fluoride in dental hard tissues was actually made by Mori chi ni (1805), first in an elephant tusk, i.e., in ivory, and then in human dental enamel.

Even in terms of control of dental caries, the potential significance of fluoride was conceived as a possibility during the past century. For example, Crichton-Browne (1892) went so far as to suggest that dental caries was a sign of nutritional deficiency of fluoride. Also, on the basis of anti-caries experiments of 100 years ago, Erhardt (1874) suggested that children and women should eat fluoride-containing pills. A number of recent investigators have done sophisticated work on the fluoride content of teeth, normal and decayed. But before the turn of the century, two studies (Wrampelmeyer, 1893; Hempel and Scheffler, 1899) reported results suggesting a higher fluoride content in intact than in decay-susceptible teeth. Other authors of the same period speculated that the fluoride content of enamel had a caries-inhibitory effect. One writer, Michel (1897), even became so specific as to suggest that caries was related to a fluoride effect on the adjacent microflora of the tooth surface. And then, to complete this ante-fluoridation period, there was a European report by a fluoridation enthusiast of seventy years ago, Deninger (1907), who went beyond speculation. He adopted in a practical manner the idea of giving some of his patients tablets containing calcium fluoride in order to control their susceptibility to dental decay.

Earliest Colorado Observations

To obtain a proper perspective, it is necessary to make comparisons between the earliest and latest discoveries. Dental lesions comparable to the 1916 observations on "Colorado brown stain" have actually been alluded to under different names from various parts of the world prior to that time. Six years earlier, right here in Colorado, a report by Fynn (1910) indicated that a majority of children born and raised in Colorado Springs had mottled teeth; but he ruled out drinking water as a potential cause. Shortly thereafter, Rodriguez (1915), who worked as a dentist with the United States Indian Service, reported on brown stains of the enamel among the Pima Indians of Arizona, and he did conclude that the condition might be due to the nature of the water supply. According to that author, Dr. Fred McKay of Colorado evidently had visited the Pima reservation shortly before presenting the famous 1916 report on the subject in collaboration with Dr. G.V. Black. Their studies will be referred to under the next heading.

Early Research on Fluoride and Dental Caries in Man and Animals

Human Studies.

Black (1916) and McKay (1916) published the first detailed studies of mottled teeth, an endemic developmental imperfection of the enamel now more properly called dental fluorosis. Black's histological studies were continued by Williams (1923) and Beust (1925), who found that not only the enamel's interprismatic substance was affected, but also the enamel rods, as well as the dentin to some extent.

Black (1916) and McKay (1916, 1928, 1929), Bunting et al. (1928) early called attention to the fact that mottled teeth, in spite of their imperfect structure, were relatively resistant to dental caries. What in retrospect may have been one of Dr. McKay's most important, yet less well known, reports was written after he had moved his dental practice from Colorado to New York (McKay, 1926), when he openly implicated local water supplies as the probable cause for endemic mottling of teeth. There followed a flood of letters to the editor expressing a mixture of congratulations, concern and critiques, and commenting on a variety of chemical culprits potentially involved. Only one letter, written by a water plant chemist from Toronto, Ontario (Hannon, 1926), happened to allude to the possible role of water fluoride: "Of the mineral elements at present known to be common to both water and enamel, the chief are calcium, phosphorus, and fluorine... But when we consider fluorine, all is at present shrouded in obscurity... I must confess complete ignorance." But alas, the writer evidently did not think in terms of a fluoride overdose, but rather a deficiency: "... should the incriminated waters prove to be all alike fluorine-free, the case for fluorine deficiency will become strong; ...". In 1931, three independent studies by Smith, Lantz and Smith (June, 1931), Churchill (September, 1931) and Velu (November, 1931) pointed to fluorine as the cause of mottled enamel, findings that were subsequently confirmed by McKay (1933), Dean, McKay and Elvove (1938) with their successful prevention of mottled enamel by changing, in endemic areas, to a water supply containing less fluorine. Masaki (1931), Ainsworth (1933), Erasquin (1935), Arnim, Aberle and Pitney (1937), Dean (1938) and Dean et al (1939) added support for the contention that fluorosed teeth (or children in endemic areas) present a certain resistance to the attack of dental caries.

The last authors (Dean, 1938; Dean et al., 1939) particularly related this to the use of water with a relatively high fluorine concentration, and found that the caries resistance also holds true for those teeth which do not show clinical evidence of fluorosis.

Animal Studies.

In the early thirties Hoppert, Webber and Caniff (1931) - rather accidentally - produced a high frequency of experimental caries in white rats fed a coarse, presumably adequate, corn diet. This gave rise to a number of caries studies in rats, in the beginning especially related to the cause and nature of the lesions (Klein and McCollum, 1931; Rosebury, Karshan and Foley, 1933; Bibby and Sedwick, 1933; and King, 1935). Later Lilly (1938) obtained a considerable reduction in the rat caries when cas...

Table of contents

• Cover
• Half Title
• Series Page
• Title
• Copyright
• Contents
• List of Figures
• List of Tables
• Acknowledgment
• About the Editors and Authors
• Introduction
• 1 Historical Perspectives
• 2 Fluoride Supplements for Systemic Effects in Caries Prevention
• 3 Topical Fluorides in the Prevention and Arrest of Dental Caries
• 4 Fluoride in the Treatment of Osteoporosis
• 5 Inorganic and Organic Fluorine in Human Blood
• 6 Is Fluoride Intake in the United States Changing
• 7 Distribution of Fluoride Among Body Compartments
• 8 The Effect of Body Fluid pH on Fluoride Distribution, Toxicity, and Renal Clearance
• 9 Fluoride Resistance in Cell Cultures
• 10 Fluoride from Anesthetics and Its Consequences
• 11 The Safety of Fluoride Tablets or Drops
• 12 Fluoridation and Bone Disease in Renal Patients
• 13 Claims of Harm from Fluoridation