Final answer:
Fluoride is the best agent for remineralizing tooth surfaces because it forms a more acid-resistant fluorapatite layer, enhances enamel uptake of minerals, and has bacteriostatic effects.
Step-by-step explanation:
The best agent for remineralizing tooth surfaces is fluoride. Fluoride aids in the remineralization process by reacting with hydroxyapatite in tooth enamel to form fluorapatite, which is more resistant to acid attacks and less soluble, thus providing better protection against tooth decay. Additionally, fluoride enhances the uptake of calcium and phosphate ions into the enamel and has bacteriostatic properties, which help reduce plaque-forming bacteria and prevent cavities. While calcium and phosphorus are important components of tooth enamel, and potassium may play a role in reducing sensitivity, fluoride is specifically beneficial for the remineralization and protection of tooth surfaces.