John W. Knutson

Studies on mass control of dental caries through fluoridation of the public water supply.

Numerous epidemiological studies (1) conducted in widely separated parts of the world clearly demonstrate that the use of fluoride drinking water during the formative period of the teeth is associated with a 60to 65-percent reduction in dental caries experience. This inverse relationship between dental caries prevalence and fluorides in drinking water approaches its maximum at a fluoride (F) concentration of 1.0 to 1.5 ppm., a concentration which Dean (2) established as the minimum threshold concentration of mottled enamel or endemic fluorosis. These findings led to the proposal that optimum amounts of fluorides be -added to the drinking water supply as a partial caries-control measure. The proposal engendered extensive field and laboratory studies on the physiological effects of fluoride ingestion (1). The results of these studies indicated that not only was 1.0 ppm. in the drinking water an optimal concentration for caries control but well within the limits of safety. In 1945, three studies to determine the caries prophylactic value of artificially fluoridated drinking water were started in the United States and Canada. A number of additional study projects have been initiated in the United States since that time. One of the studies started in 1945, that in Grand Rapids, Mich., serves as the basis for this preliminary report.

The Effect of topically applied Fluorides on Dental Caries Experience. V. Report of Findings with Two, Four and Six Applications of Sodium Fluoride and of Lead Fluoride.

Previous reports (1, 2, 3, 4) in this series on the effect of topically applied fluorides on dental caries experience indicated: (1) Approximately 40 percent reduction in dental caries incidence is effected when the initial application of a 2-percent sodium fluoride solution to the teeth is preceded by dental prophylaxis and subsequent applications are made at the rate of one or two per week to a minimum of 7 and a maximum of 15. (2) The caries prophylactic effect of 15 applications is not greater than that obtained with 8 applications. (3) Two, four and six applications of a 2-percent sodium fluoride solution effect 9, 20 and 21 percent reductions, respectively, when the initial application is not preceded by dental prophylaxis. Jordan and his associates, using a 2-percent sodium fluoride solution and the same technique of application described here, reported 5, 10, and 21 percent reductions in caries incidence respectively following one, two and three applications (5). It is the purpose of this report to present the results of additional studies designed to determine the minimum number of applications of 2-percent sodium fluoride required to achieve maximum caries reduction, and to test the comparative effectiveness of lead fluoride. The results of laboratory investigations have suggested that lead fluoride might be more effective than sodium flouride as a topical agent for the prevention of dental caries (6, 7). Briefly, the results of the study indicate that four applications of a 2-percent solution of sodium fluoride, applied as described in the section on materials and methods, and preceded by dental prophylaxis, are the minimum number required to give maximum reduction in caries incidence. Two applications of sodium fluoride resulted in 21.7 percent less initial caries in treated teeth than in untreated teeth, four treatments reduced initial caries in treated teeth by 40.7 percent, and six resulted in a 41.0-percent reduction. No significant reduction was shown with two, four, or six applications of a saturated lead fluoride solution.

Simplified Procedure for the Collection of Basic Data for Dental Program Planning and Appraisal

1. Demonstrations now in progress which hold great promise for the early development of positive methods of preventing specific dental diseases. 2. Widespread endorsement by members of the dental profession of a program to increase dental research facilities and activities, to facilitate education of the public in matters relating to dental health, and to make dental health services available to all. 3. The initiation and sponsorship of legislation which would provide specific financial support for a broader program of research, education, and service. 4. Current dental surveys containing specific. provisions for thd collection of basic data for community program planning, their use heretofore having been largely limited to epidemiological studies on dental diseases.