What effect does fluoride have at high concentrations?

Fluoride at high concentrations is known to have a bactericidal effect. This means that it can actively kill bacteria, especially those that are responsible for dental caries. High levels of fluoride can disrupt enzyme activity within the bacteria, inhibit nutrient metabolism, and interfere with the bacteria's ability to maintain its cell membrane potential. This ultimately leads to the death of the bacterial cells.

It's important to recognize that while fluoride has protective effects against caries at lower concentrations, its bactericidal properties emerge largely at higher concentrations. This distinction is critical in both therapeutic and preventive dental contexts, where the right concentration can maximize benefits while minimizing risks.