1. Anti-Erosion

Anti-Erosion

Dental erosion is prevalent in children and adults globally, with some researchers finding it present in approximately half of adolescents (Al-Dlaigan et al. 2001; McGuire et al. 2009). Estimated prevalence in some locations can be found in Figure 6.

Estimated prevalence of dental erosion among youth

Figure 6. Estimated prevalence of dental erosion among youth

(Nayak et al. 2010; Hou et al. 2009; Wiegand et al. 2006; Deery et al. 2000; Kazoullis et al. 2007; Wang et al. 2010; Manaf et al. 2012; Mantonanaki et al. 2013; Nahás et al. 2011)

Dental erosion occurs primarily due to the excessive presence of non-bacterial extrinsic acids (especially dietary acids such as acidic drinks), as well as intrinsic gastric acid associated with gastroesophageal reflux disease (GERD) and bulimia (Moazzez et al. 2004; Bouqot & Seime 1997). Dental erosion involves the demineralization and softening of the tooth surface, which once softened, is highly susceptible to abrasion and attrition (Figure 7). A diagnosis of erosion can be made based on the pattern of surface loss of enamel and/or dentin (Figures 8a,b)

Figure 7. Demineralization associated with dental erosion

Demineralization associated with dental erosion
Generalized erosion
Severe palatal erosion and loss of Courtesy of Prof. Ian Meyers tooth structure

Figure 8a. Generalized erosion
Courtesy of Prof. Ian Meyers

Figure 8b. Severe palatal erosion and loss of tooth structure.
Courtesy of Prof. Ian Meyers

Unlike dental caries where demineralization is initially mainly subsurface and is also reversible in its early stages, dental erosion involves repeated demineralization of the surface with subsequent surface loss and this process is irreversible (Figures 9a, b).

Dental caries process

Figure 9a. Dental caries process

Reversible
Enamel crystals are weakened, but remain structurally intact. The early caries process is reversible

Dental erosion process

Figure 9b. Dental erosion process

Irreversible
Enamel crystals are damaged structurally from the surface down into the tooth. The erosive process is irreversible

Mechanism of action for anti-erosion effect of stabilized stannous fluoride

The deposition of stannous ions at the tooth surface helps protect it against dental erosion (Faller & Eversole 2014):

  • Deposition of stannous fluorophosphate or stannous oxide layers onto enamel surfaces has been reported after stannous fluoride treatment
  • Deposition occurs primarily as a result of the attachment of the stannous ion to free phosphate sites on the surface of enamel
  • Stannous forms a protective layer on the surface that is highly resistant to acids

A recent in vitro study compared the ability of various fluoride toothpastes to form a protective barrier layer (Faller & Eversole 2014). The toothpastes evaluated included 1,100 ppm stannous fluoride, 1,100 ppm sodium fluoride, 1,000 ppm sodium monofluorophosphate and 1,400 ppm amine fluoride. The study involved exposing etched samples to toothpaste-saliva slurries, rinsing them, and then exposing them to 2% alizarin Red-S. Dye deposition was assessed using a 5-point scale, with 0 being no dye deposition and 4 being complete dye coverage. A low score indicates a barrier layer is present, preventing the deposition of dye. Thestannous fluoride toothpaste had the lowest score, 0.25. At the other extreme, amine fluoride resulted in a score of 3.7 (Figure 10). This in vitro test confirmed the ability of stannous to form a protective barrier layer, and demonstrated that stannous fluoride is a preferred fluoride for delivering an enamel protection benefit via a barrier mechanism to erosive acids.

Figure 10. Degree of dye deposition on enamel samples following exposure to toothpaste slurry followed by dye

* Average deposition of stain (based on the 5-point scale)

Degree of dye deposition on enamel samples following exposure to toothpaste slurry followed by dye

Other in vitro tests have also demonstrated the superior protective effect of stannous fluoride-treated enamel slabs in comparison to sodium fluoride-treated enamel slabs during an erosive challenge (Figure 11; Faller 2012). Exposure to dietary acid in an erosion cycling model resulted in surface demineralization and surface loss for the slabs treated with sodium fluoride toothpaste slurry while minimal demineralization or surface loss occurred with the slabs treated with stannous fluoride toothpaste slurry.

Stannous fluoride vs. sodium fluoride in in vitro treated enamel slabs

Figure 11. Stannous fluoride vs. sodium fluoride in in vitro treated enamel slabs

Stannous fluoride protects against erosion
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