In the typical sequence of a prophylaxis, what is the third step?

• A. Remove supra-gingival plaque and calculus.
• B. Polish tooth surfaces.
• C. Apply fluoride if indicated.
• D. Provide oral hygiene instructions.

Answer: (C)

The sequence is arranged so that the teeth are first freed of deposits, then the surfaces are smoothed, and finally a protective agent is applied to maximize benefit. Applying fluoride after removing plaque and calculus and after polishing ensures the enamel is clean and receptive; a smooth, plaque-free surface allows fluoride to contact and remineralize the enamel effectively, enhancing caries protection. If fluoride were applied earlier, it could be washed away or not penetrate as well, and polishing helps prepare the surface for optimal fluoride uptake. The remaining step, giving oral hygiene instructions, is best left for after the in-office procedures so the patient can implement guidance with a clean mouth.