Pharmacokinetics of fluoride in toddlers after application of 5% sodium fluoride dental varnish.
Level 4 - case-series / case-control
Small single-arm pharmacokinetic case series (n=6) with baseline comparator
PubMed 25136045 · doi:10.1542/peds.2013-3501
What was done
Researchers evaluated the pharmacokinetic safety of 5% sodium fluoride dental varnish in 6 toddlers aged 12 to 15 months. Fluoride excretion was measured from urine extracted from disposable diapers over a 5-hour period following varnish application and compared to baseline urine measurements taken on a separate day. Urinary measurements obtained by rapid diffusion were used to extrapolate plasma fluoride concentrations.
What was found
The mean estimated plasma fluoride concentration was 13 μg/L (SD, 9 μg/L) at baseline and 21 μg/L (SD, 8 μg/L) across the 5 hours post-application. The mean estimated peak plasma fluoride concentration post-treatment was 57 μg/L (SD, 22 μg/L). Average retained fluoride was 20 μg/kg (SD, 4 μg/L), which was 253 times below the acute toxic threshold of 5 mg/kg.
Why it matters
These findings provide preliminary pharmacokinetic evidence that routine application of 5% sodium fluoride varnish in toddlers according to pediatric guidelines is well below acute toxicity thresholds.
Limits
The study is limited by an extremely small sample size (n = 6) and a narrow age range (12–15 months). Plasma concentrations were not directly measured via blood sampling but were indirectly extrapolated from diaper urine extractions over a short 5-hour window, and long-term cumulative exposure or fluorosis risk was not assessed.
Cited by
- context Fluoride from professional fluoride varnish enters the bloodstream within 10 minutes of application.