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

Abstract

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.