Individual Variability of Fluoride Bioavailability in Saliva and Plaque

Objectives: In contrast to traditional drug kinetics, the bioavailability of fluoride at teeth depends on exogenic influences. Therefore, it was the aim of this clinical study to assess the F ˉ content, provided by saliva soluble DENTTABS^® compared to dentifrice ELMEX^®, in saliva and plaque. Methods: Five trained volunteers brushed their teeth in the morning for 3 min. with one of the products, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva, plaque, and water after rinsing was measured, and the F ˉ content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using Mann-Whitney-U test and Spearman correlation. Results: Immediately after brushing the fluoride concentration in saliva was 165 ppm for DENTTABS^® (range 110 – 259 ppm) and 120 ppm for ELMEX^® (range 70-183 ppm), and in plaque was 382 ppm for DENTTABS^® (range 60-870 ppm) and 180 ppm for ELMEX^® (range 43-278 ppm), respectively. 3.4 – 11.6 ppm F ˉ were expectorated after rinsing, 47 – 233 ppm F ˉ left in brush slurry. All plaque F ˉ levels were elevated for 30 min. until 2 hours, decreasing after 6 hours to baseline (260 ppm for DENTTABS^®, 200 ppm for ELMEX^®). According to the highly individual kinetics profile of F ˉ in saliva and plaque, both levels of bioavailability correlate for the first 30 min., and in contrast to plaque levels, the F ˉ content of saliva is mainly back to baseline after 2 hours. Conclusion: Fluoride levels in saliva and plaque are interindividually highly variable. However, the F bioavailability of tooth brushing agent DENTTABS^®, suspended in saliva, was statistically significantly elevated (p= 0.008) compared to ELMEX^® dentifrice.