Professionally applied fluorides are usually high concentration neutral Fluorides (e.g. 2 % NaF) that can be easily dispensed in disposable trays as either gels or foams (Table 9.1). Although foams require less material than gels to supply the same amount of fluoride, much of the fluoride benefit from these high concentrations is limited by the concentration and availability of calcium and phosphate.

Traditional prophylaxis of teeth before application of these products is not recommended and application of fluoride should occur after the biofilm is allowed to form. Late afternoon appointments, or preferably asking the patient not to brush on the day of the appointment, have benefits. However, asking patients not to brush should occur with selected, dentally aware patients otherwise the wrong message will be sent about oral hygiene and oral health.

Directions for fluoride gels and foams:

Operators must be aware not to exceed the ‘probable toxic dose’ measure of 5 mg/kg for fluoride of body weight per day, and age recommendations must be adhered to. High concentration gels are not recommended for children younger than 10 years of age because of the potential of ingestion.

Acidulated Phosphate Fluoride (APF) gels are also high concentration fluorides (1.23 % fluoride) that are recommended by some clinicians (Table 9.1). In vitro studies have shown that APF provides more protection than high concentration NaF gels in both endogenous erosion and particularly in wine tasters erosion where the acidic challenge is extreme [11, 15]. For example, the use of APF with professional wine tasters has shown a high degree of protection especially when biofilm is allowed to establish for at least 24 hours before a wine tasting event. Professional application of APF the day before the tasting and supplemented periodically by patient-applied home preventive care is very effective. In addition, acidified fluoride gels over erosion lesions seem to show higher abrasion resistance than neutral fluorides [16].

Although the pH of APF is about 3.0–3.5 and may not seem appropriate for erosive cases, there are some benefits when saliva is compromised. Here, the low pH of the APF demineralizes the tooth surface, allowing calcium ions from the tooth to be used with the phosphate and fluoride ions in the APF for remineralization. Again, close-fitting-trays are recommended and post-application instructions are similar to those described above. However, the low pH of the product is contra-indicated in patients who have teeth restored with glass ionomer cements and with indirect ceramic restorations.

Directions for APF:

In vitro studies have consistently shown that bivalent metal-ion fluorides, such as Stannous Fluoride (SnF ₂ ) (Table 9.1), can protect tooth surfaces from acid attack. Although it has been attributed to the remineralization effects of fluoride, in reality these products provide their effect by the deposition of stannous fluorophosphate (and stannous oxide) precipitate on the tooth surface that is highly insoluble to acid. This occurs when stannous attaches to free phosphate sites on the enamel surface. This precipitate is also effective in obturating patent dentinal tubules, thereby eliminating hypersensitivity.

Where the stannous products are presented as toothpastes (e.g. ProHealth products), they can be used professionally as prophylaxis pastes, and where they are available as gels (e.g. Gel-Kam) they can be used professionally (similar to the gels described above) in closely fitting trays to ensure complete coverage (even though most gels are applied with a finger or toothbrush during home application).

Extending the physical presence of fluoride can also occur when the fluoride is used as a varnish (Table 9.1). Varnishes are high-concentration fluorides (e.g. 5 %) that provide more effective remineralization because of superior ‘contact time’, allowing more calcium and phosphate from saliva to be utilized due to a longer period of salivary flow. Unused or excess fluoride is still discarded by swallowing. There are differences of opinion about the use of fluoride varnish. Professionally directed spot application onto very active and affected areas, supplemented with home fluoride use, seems a common approach, while other operators recommend complete coverage. Although the positive effects of these fluorides are based on research with high caries risk patients, evidence on their effects on erosion is slowly becoming clearer. Within an erosive environment, varnishes on their own are effective in erosive wear (i.e. combination of acid and mechanical action) [17]; however their long-term effect seems uncertain and should be supplemented with a home preventive program.

Directions for varnish application:

Although the fluoride content of varnishes is traditionally high, the amount ingested when compared to high concentration gels and foams is comparatively low because of the slow fluoride release, making it preferable for younger children below 10 years of age.

One group of products that include calcium and phosphate for remineralization are those with the Recaldent technology (i.e. CPP-ACP: casein phosphopeptide – amorphous calcium phosphate). Here the calcium is stabilized by the protein CPP, preventing precipitation during storage within the dispensing tube. After application, when the oral pH drops during an acid challenge, the calcium is released from the CPP providing supersaturated conditions and therefore remineralization [18