In which scenario would a dental assistant apply topical fluoride?

Topical fluoride is primarily applied after cleaning and polishing teeth to enhance remineralization and strengthen the enamel. This application helps to protect against caries by providing a concentrated fluoride treatment that can penetrate the enamel and promote its resistance to decay. After a thorough cleaning, the surface of the teeth is free from plaque and debris, allowing for optimal absorption of the fluoride. This preventive measure is part of routine dental care, especially for patients with a higher risk of cavities.

In other scenarios, such as before taking radiographs, the application of topical fluoride would not be appropriate or beneficial, as the focus at that time is on obtaining clear images rather than treating the teeth. During a tooth extraction, the focus would be on managing the procedure rather than applying fluoride. Lastly, sealing the edges of a composite filling is not a circumstance where topical fluoride application would directly contribute to the effectiveness of the filling or the surrounding tooth structure. Thus, the application of topical fluoride after cleaning and polishing is the most appropriate and beneficial scenario.