Basil G. Bibby

A Test of the Effect of Fluoride-Containing Dentifrices on Dental Caries

An analysis (1) of available information on the mode of action of fluorine in reducing the activity of dental caries suggested to us that this effect was largely the result of a reaction between the dilute solution of fluorides contained in the drinking water and the external surfaces of the teeth. Strong support for this hypothesis was given by our demonstration (2) that dental caries in school children could be considerably reduced by making as few as 3 applications a year of a more concentrated fluoride solution. This immediately suggested the possibility that more frequent applications of fluorides to the teeth, such as could be brought about by the use of fluoride-containing dentifrices, should produce like effects even if mixtures of a much lower fluoride content were used. This paper reports the results of a 2 year clinical study of the subject. In September 1942, 4 groups of test subjects were organized from amongst the residents of 2 Catholic Orphanages and the students of Tufts College Dental School. These patients were examined by a dentist using a mirror and probe and all dental defects, fillings and absent teeth recorded. On the basis of the dental conditions of the patients each group was divided into subgroups. These were set up to contain almost identical numbers of persons showing average, more than average and less than average activity of dental decay. This resulted in each experimental subgroup having approximately the same total number of non-carious tooth surfaces at the beginning of the experiment. These various subgroups of patients were then placed on experimental and control dentifrices. Table I shows the composition of various groups at the beginning of the experimental regimes. The test dentifrices were supplied by the Proctor and Gamble Company, and prepared by adding sodium fluoride to a liquid dentifrice similar to their commercial product and to a specially prepared paste. The concentration in the various dentifrices was as follows: paste 3702, 0.01%; liquid 3724, no fluoride; liquid 3725, 0.01%; paste 4211, 0.1%; liquid 4213, 0.1%0 at approximately pH 4.0. To ensure proper use of dentifrices, orphanage patients were instructed to use them daily and arrangements were made to provide supervision of all study groups. At St. Vincents Orphanage the supervising dental hygienist met groups of children and gave instruction in the procedure of tooth brushing and supplied each child with a tooth brush. Thereafter she visited the orphanage regularly

The Effects of Various Ions on Enamel Solubility

Several reports in the literature indicate that the solubility of enamel in acids can be changed by the action of various ions. Miller (1) using silver nitrate was unable to show retardation in enamel decalcification. The research work of Rickert (2) contradicted this and led him to believe that increased resistance to decalcification of silver nitrate-treated enamel was due to the clogging of tooth substance with reduced silver which prevented the penetration of acids. Hill and Arnold (3) studied the effects of silver nitrate on powdered enamel and found that after treatment, the solubility of enamel was significantly reduced. Difference in enamel solubility in acetate and maleate buffers was attributed by Benedict and Kanthak (4) to the formation of calcium maleate which acted as a protective coating over the enamel particles. Volker (5) and Bibby (6) investigated the effect of fluorides on enamel and concluded that the fluorine ion produced marked reduction in solubility. Because little or no consideration has been given to the effects of other ions on the solubility of enamel, it seemed to us worthwhile to investigate the matter. The choice of the ions used in the experiments was determined by a consideration of the mechanisms whereby the phenomenon of reduced solubility might occur. In order to better understand these, an examination of the chemical nature of enamel is necessary. This will be limited to facts relevant to the adequate understanding of certain assumptions which are made in this paper. Tooth enamel is a crystalline substance showing a characteristic x-ray diffraction pattern. Moreover, this pattern is practically identical with that given by bone, dentin and certain synthetic or natural inorganic materials, such as fluorapatite. On the basis of these x-ray findings these substances have been included in the general class of apatites. It should be remembered that this apatite classification refers only to a particular atomic pattern or arrangement in the crystal lattice and not to any constancy of chemical composition. For instance, McConnell (7, 8) has pointed out that a large number of substitutions are possible in the general apatite pattern. If X10(ZO4)6. (F20H2C12) represents the general formula for the apatites, then X may be calcium, lead, manganese, potassium, strontium and cesium or in lesser amounts yttrium, lanthanum, titanium, iron, aluminum and magnesium; Z may be chromium, phosphorous, arsenic, vanadium, silicon, and carbon. Further evidence of the complex and variable nature of the apatites is obtained from the work of Eisenberger, Lehrman and Turner (9). In their critical review of the literature on the system

Preliminary Reports on the Effect on Dental Caries of the Use of Sodium Fluoride in a Prophylactic Cleaning Mixture and in a Mouthwash

Previous reports (1, 2) have shown that the activity of dental caries can be reduced by bringing aqueous solutions of sodium fluoride into contact with the freshly cleaned tooth surfaces of children. Unfortunately, the methods so far employed for this purpose are somewhat time-consuming and require the employment of techniques not usually used by dentists or dental hygienists. Therefore it seemed desirable to determine whether alternative and simpler methods of topical treatments with fluoride solutions might not bring about comparable reductions in caries activity. For this reason it was decided to study the effects of: 1. Incorporating sodium fluoride in a cleaning mixture which could be used in a routine way by dental hygienists giving oral prophylaxes, and 2. The use of a mouthwash containing sodium fluoride. Because it had been shown (3) that fluoride solutions buffered to an acidity of pH 4 reduce the solubility of enamel and dentin much more than do ordinary aqueous fluoride solutions, it seemed advantageous to use such acidulated preparations in these studies.

Penicillin and Caries Activity

To test for interference with carbohydrate fermentation, the following procedure was used: 4 cc. of pooled stimulated saliva added to 1 cc. of a 20% glucose solution were incubated at 370 C. for 4 hours. At the end of this period, the pH of the saliva-glucose mixtures was determined electrometrically. As a control, 4 cc. of the saliva were incubated with 1 cc. of distilled water. The test agents were added in various concentrations to the saliva-glucose mixtures before incubation. Results typical of 20 tests are shown in Table I. Pooled saliva and glucose alone produces a pH of 4.0 after 4 hours incubation. However, when 10 units of penicillin are present, no acid is formed.