Re:How does it get below the gum line? (Score 1)

It sounds like the type of tooth decay that this treatment is trying to prevent is decay on enamel surfaces. Through ion replacement, the fluoride would strengthen the ion matrix in the enamel only. Cementum, which covers the tooth below the natural tooth's crown (under your original gumline) obtains its hardness from mineralized organic material rather than inorganic ion matrix, so theoretically, the treatment will not benefit these areas. You're right, anaerobes will still be an issue, and periodontal health will still be at risk without good oral hygiene.