Determining the Size of a SDF Drop and the Margin of Safety on Young Children

Background: In the United States, Elevate Oral Care 38% Silver Diamine Fluoride (SDF) Advantage Arrest is approved by Food and Drug Administration (FDA) as a devise for dentin desensitization in adults, and used off-label for arresting caries lesions on primary teeth. Manufacturer’s indications are to use 1-2 drops on adults. Current guidelines for use in children, recommend using 1 drop. Clinical trials in more than 4000 children indicate safety (absence of acute toxicity symptoms), but little is known about the effects of repeated exposures.

Objective: To investigate the size of a SDF droplet dispensed from the bottle and its relation to EPA reported toxic levels of silver and fluoride.

Methods: A single drop of each SDF sample weighed in a small disposable weigh dish (Fisher Scientific, USA). For volume measurement a single drop of each SDF sample was placed in a micro vial and measured by a micropipette. Measurement of the weight and volume were acquired from two separate drops. Expected size of a drop was 25 µL.

Results: Mean volume of a drop was 32.55 (±1.89) µL and mean weight was 40 (±4) mg. As reported by other studies, this average drop would have approximately 1.64 to 1.76 mg of fluoride, and 8.71 to 8.08 mg of silver. Using 6 µL (less than 1/5 of a drop) on an adult, the fluoride exposure would be below the EPA oral reference dose but silver exposure would exceed the EPA oral reference dose for cumulative daily exposure over a lifetime.

Conclusion: SDF is an additional tool as part of a comprehensive caries management plan. Minimal exposure and occasional use should pose no danger of long-term toxicity. As with all other products used on young children, a careful evaluation of risk/benefits and alternative options for treatment should be discussed with the parents.