Fluoride ions

Fluoride is well known to form protective CaF2-layers on teeth, leading to increased protection from caries and to a lower extent also from erosion (Wiegand & Attin 2003).

The effect of fluoride ions in mild to moderate conditions:
  • Under acidic conditions, the dissociation of fluoride ions is enhanced, thus creating a higher concentration of protective fluoride ions compared to pH neutral fluoride solutions (Ganss et al. 2008).
  • Long term and regular application of highly concentrated fluoride products has been shown to be beneficial to preventing erosion in vitro (Ganss et al. 2001b).
  • Furthermore, regular intensive fluoridation with toothpaste, dental rinse and gel was more effective in protecting enamel and dentine from erosion than regular application of fluoride toothpaste alone or no fluoridation at all (Ganss et al. 2004).

The effect of fluoride ions in harsh conditions:
  • Although being low-soluble in the caries relevant pH-range, CaF2-layers are relatively easily soluble when exposed to severe erosive attacks and show, particularly in vitro, only low stability against acid impacts.
  • Therefore, the effect of sodium fluoride as an erosion protective agent in enamel in vitro is limited.
  • More recent studies demonstrated that the efficacy of fluorides with regard to erosion inhibition is largely determined by the type of fluoride compound. Particularly when used in combination with stannous (or other polyvalent metal) ions, fluorides show good erosion inhibiting effects (Ganss et al. 2009, Hove et al. 2008).

The effect of fluoride ions on dentine:
  • Topical fluoridation leads to considerable amounts of retained fluoride, even in deeper layers (ten Cate et al. 1995, Hellwig et al. 1992), thus making dentine less prone to acidic challenges, at least as long as the outermost demineralised collagen-rich layer is not removed (Ganss et al. 2001b, Ganss et al. 2004).
  • The protective effect of fluoride—especially amine fluoride (Lussi et al. 2004)—on exposed dentine will also reduce hypersensitivity by forming a dense CaF2-layer and thus reducing a patient's symptoms (Mordan et al. 2000).

Other uses of fluoride ions for erosion prevention:
  • Soft drinks supplemented with tooth minerals (fluoride, calcium), as opposed to ordinary soft drinks, have been tested for protection against erosion with mixed results (Amaechi & Higham 2005).
According to some erosion experts, the prevention of erosion by adding fluoride to soft drinks is limited, while the addition of calcium to reduce the erosive potential of acidic drinks looks promising (Lussi & Jaeggi 2009). Many calcium-fortified drinks, such as orange juice, are available on the market today.