Which of the following is NOT part of the SDF application protocol?

• A. Rinse with water after application
• B. Isolate tooth with cotton rolls
• C. Moisten lesion with the smallest amount of SDF using a microbrush
• D. Avoid touching intra- or extraoral soft tissues

Answer: (A)

The concept tested is how to apply silver diamine fluoride (SDF) effectively and safely. The protocol aims to localize SDF on the lesion, keep the field dry, and minimize contact with soft tissues so the solution can act without dilution or irritation.

Rinsing with water after application is not part of the protocol because it would wash away the SDF and reduce its effectiveness. After carefully isolating the tooth, drying the lesion, and applying a tiny amount of SDF with a microbrush, you want the solution to remain in contact with the lesion to interact with the demineralized tissue. Blotting away any excess with a cotton roll or gauze is appropriate, but rinsing with water would undermine the treatment.

By contrast, isolating the tooth with cotton rolls, applying the smallest amount with a microbrush, and avoiding contact with intra- or extraoral soft tissues are all steps intended to maximize retention of the SDF at the lesion site and minimize unintended staining or irritation.