AN EVALUATION OF THE EFFECTIVENESS AS A CARIES CONTROL MEASURE OF THE TOPICAL APPLICATION OF SOLUTIONS OF FLUORIDES

¹ DENTAL SECTION, STATES RELATIONS DIVISION, U. S. PUBLIC HEALTH SERVICE, WASHINGTON, D. C.

In summary review, chemical studies were conducted to test the effectiveness of different fluoride solutions. These studies indicated that there may be fluoride solutions more effective than sodium fluoride. I hope such solutions are found. However, until such solutions are tested clinically, it is strongly indicated from the results of the tests with lead fluoride that we consider the use of any other fluoride solutions than sodium fluoride as experimental.

Consideration has been given in the laboratory to the difference in pH level of the solutions used. The conclusion was reached by one group of investigators that a pH as low as 2.6 would be noninjurious to the tooth tissue. I, myself, am not ready to accept that conclusion. I think this matter deserves further study, particularly in view of the fact that it has been demonstrated that decalcification can occur and does occur at a pH of 5, and, certainly, definitely at a pH of 4. Studies are now being conducted that should shed additional light on pH very shortly. Some of these studies are concerned with tooth surface patterns or tooth surfaces as seen through the electron microscope. Until it has been verified, I do not think I would use a solution with a pH as low as 2.6. As a matter of fact, I do not think the pH should be varied in any way until verified by clinical studies.

There was great variation in the spacing of the applications. Some of the investigators gave three applications a year, spaced four months apart. In all our studies, we gave the applications at a minimum rate of one a week, and a maximum rate of two a week to whatever total number was desired. It is merely my impression that if four applications do give the most effective results and four are required to give the full effects of the topical fluoride that we elect to use, it seems to me that the earlier we get those on the teeth, the better. It is also very likely that if you do space the treatments far apart, it would be important to precede each application with a cleansing.

Concentration of the solutions used varied widely. Most of the work has been done with 2 per cent sodium fluoride solution. Indications are that a 1 per cent solution may be fully as effective, but again this concentration has not been tested as fully as the 2 per cent solution.

One concluding item of interest is the effect of topical fluorides on lactobacillus counts. When we treated children's teeth, that is, the full mouth, and studied the lactobacillus acidophilus counts, we got no reduction in the lactobacillus acidophilus counts. Now, that can be explained, I am quite sure, and really does not reflect on the effectiveness or the usefulness of lactobacillus acidophilus counts. In our first study on this particular phase, we had twenty-five children in each group, both control and experimental. We made lactobacillus acidophilus counts at intervals of three months, and there was no change during the year. We followed a similar procedure with another study of forty children in each group. Again, we made lactobacillus acidophilus counts, but at time intervals of one year, and for a period of two years we got no change in the counts.