Effectiveness of different concentrations and frequencies of sodium fluoride mouthrinse

The effect of different concentrations and frequencies of use of a sodium fluoride mouthrinse was tested within the same study population of 2,014 students in Polk County, FL. Five study groups were assigned as follows: a daily .05% mouthrinse, a daily .2% mouthrinse, a weekly .05% mouthrinse, a weekly .2% mouthrinse, or a weekly placebo mouthrinse. After two years, there was a significant difference in mean incremental DMFS between the daily .05% group and the control. There was also a significant difference in mean incremental proximal surfaces between both the weekly .2% and daily .05% with the control. When the study groups were combined by similar frequency or concentration, there were significant differences for all groups from the control. No ctifferences were found between different concentrations at the same frequency or between different frequencies at the same concentration. School based caries preventive programs involving the use of a weekly 0.2% neutral sodium fluoride mouthrinse have been rapidly gaining acceptance with public health and school officials. The use of a self-administered mouthrinse vehicle offers a convenient approach to the provision of topical fluoride to large groups of students in areas where the water supply lacks adequate fluoride. The two mouthrinse procedures most used have been the 0.2% NaF (0.09%F) weekly regimen and the 0.05% NaF (0.02%F) daily regimen. 1’2 There have been at least two studies which have shown caries reductions of 27-36% resulting from daily school use of a mouthrinse containing 0.02-0.0225% of fluoride ion. a’4 Four or more studies have shown 16-44% caries reductions from the weekly school use of a mouthrinse containing 0.09-0.3% fluoride ion. ~-8 Other trials have shown beneficial results from the biweekly use of 0.045-0.225% concentrations of fluoride ion. °’1° Thus, it becomes apparent that studies testing different frequencies and concentrations within the same study population are necessary to establish the most effective procedure. A.J. Conti, DMD, MPH S. Lotzkar, DDS, MPH There is some evidence that a more frequent rinse may be more effective. Moreira and Tumang compared three times weekly, weekly, and biweekly frequency use of a 0.045% fluoride ion rinse and found a greater reduction in DMFS with the three times weekly rinse than with either the weekly or biweekly frequencies. There was a 22-24% greater reduction in DMFS with the more frequent rinse. 9 Two other studies also have been reported which indicate that frequency of rinsing may be of more importance than concentration. 11’12 The purpose of this study was to compare the relative effectiveness of daily and weekly rinses at concentrations of 0.02% and 0.09% fluoride ion. This report presents interim findings after 18 months. Methods and Materials The study was conducted in eight Polk County, FL, junior high schools located in the neighboring towns of Winter Haven, Lakeland, Haines City, Bartow, and Lake Wales where water fluoride level was less than 0.3 ppm. Baseline examinations were conducted by two examiners on 2,014 seventh graders who averaged 12.5 years of age. The participants (who had signed parental permission) were then allocated to study groups by random permutations of five after stratification by sex and race within each school as follows: Group D.05 rinsed daily with a 0.05% NaF solution (0.02%F), Group D.2 rinsed daily with a 0.2% NaF solution (0.09%F), Group W.05 rinsed weekly with a 0.05% NaF solution, Group W.2 rinsed weekly with a 0.2% NaF solution, and Group C rinsed weekly with a placebo solution containing 0.1% NaC1. The rinses were dispensed in 10 ml aliquots, and delivered to the classrooms by aides. The one-minute rinsing procedure was then supervised by the teachers. The study coordinator or her assistants monitored the rinsing procedure in the classrooms on a regular rotating basis. Participation records were maintained by the classroom teachers. Most of the students who remained in the study after 18 months missed less than 15% of the maximum number of rinses possible. PEDIATRIC DENTISTRY: Volume 4, Number 4 305 The follow-up examinations to determine caries increments were conducted by the same two examiners on the same students examined by each at the baseline. The examiners were not aware of group assignments and did not consult baseline findings during the incremental exam.