Fluoride gels

A very early study suggested that fluoride uptake was enhanced in a low pH environment [180]. Because of this, fluoride gels are often formulated to be quite acidic, typically of pH around 3. Typical products include an acidic phosphate fluoride gel that is 1.23% fluoride (equivalent to 12,300 ppm), an acidic sodium fluoride gel (0.5% fluoride, 5000 ppm) and a stannous fluoride gel (0.15% fluoride, 1000 ppm) [183]. All of these formulations are acidic, and are generally designed for use by dental professionals. There are also products for home use, which are also on the acid side of neutral, and which also contain high levels of fluoride [184]. 

Fluoride-containing varnishes are designed to be painted onto the teeth and retained for a few hours at least, during which they release fluoride close to the tooth surface [188], Like fluoride gels, they are intended for use by dental professionals, but have the advantage that they are considered to be easy to apply. They have an acceptable taste and contain lower amounts of fluoride than gels. They contain either sodium fluoride or difluorosilane as the active ingredient. 

Fluoride varnishes have, though, been shown to be effective in preventing caries in children [190,191]. Applied at six month intervals, these varnishes were found to be as effective as fluoride gel [191]. Some reports conclude that more frequent applications are desirable, for example, four times a year and there is also some evidence that three applications within a week, at yearly intervals might be beneficial [192,193]. However, overall the evidence is inconclusive. 

D.W. Johnston, D.W. Lewis, Three-year randomized trial of professionally applied topical fluoride gel comparing annual and biannual application with/without prior prophylaxis. Caries Res. 29 (1995) 331-336. 

L. Seppa, T. Leppanen, H. Hausen, Fluoride varnish versus acidulated phosphate fluoride gel A 3-year clinical trial. Caries Res. 29 (1995) 327-330. 

A number of studies have reported that topical fluoride application may reduce dental hypersensitivityJ ° These results have been found when concentrated dosage forms have been applied ranging from 8% stannous fluoride gels to 33.3% sodium fluoride paste. It has been shown that commercial dentifrices containing stannous fluoride may also decrease dental hypersensitivity. Also, a combination of stannous fluoride and potassium nitrate is marketed by one manufacturer to reduce sensitivity. Varnishes containing sodium fluoride have also been shown to reduce dental hypersensitivity. 

Ripa, L.W. Review of the anticaries effectiveness of professionally applied and self-applied topical fluoride gels. J. Public Health Dent. 1989, 49 (5), 297-309. 

Ripa, L.W. Leske, G.S. Sposato, A. Varma, A. Effect of prior toothcleaning on biannual professional APE topical fluoride gel-tray treatments. Results after two years. Clin. Prevent. Dent. 1983, 5 (4), 3-7. 

Fluoride can cause gastrointestinal damage (9). In 10 subjects, 3 g of a 0.42% fluoride gel caused mucosal petechiae and erosions in 7 cases there were histopatho-logical changes in nine cases, mostly affecting the surface epithehum (8). The authors advocated the use of a low concentration of fluoride gel instead of a 1.23% gel in small children, in order to avoid adverse gastric effects. 

Fluoride in therapeutic doses can cause atopic dermatitis (9). Two patients who used fluoride gel preparations apphed to the teeth developed papulonodular eruptions similar to halogenodermas (10). 

Spak CJ, Sjostedt S, Eleborg L, Veress B, Perbeck L, Ekstrand J. Studies of human gastric mucosa after application of 0.42% fluoride gel. J Dent Res 1990 69(2) 426-9. 

D Bohrer, Z Hirschfield and 1 Gedalia, Fluoride uptake in vitro by interproximal enamel fiom dental floss impregnated with amine fluoride gel , J. Dentistry 1983 11 271-273. 

A thorough review of the use of polymeric conductors as supports for fuel cell catalysts is provided along with recent results in Chapter 13 of diis volume. However, there have been a few other recent developments that are of interest For example, a novel polyvinylidene fluoride gel electrolyte membrane has been studied for use in lithium batteries. Its breakdown voltage has been found to approach 5 V and it exhibits a condcutivity on the order of 0.1 mS cm" (41),... 

Dental fluoride gels are normally acidic in order to obtain a better effect. However, when the salivary glands are damaged by radiation or chemotherapy, the acidic licensed preparations are often not tolerated, as they will be too irritant on the mucosa. A neutral dental fluoride gel, prepared in the pharmacy, would be the medicine of choice. Formulations containing ethanol can also irritate a damaged oral mucosa. 

Bottenberg P, Slop D, Remon JP, De Muynck C, Coomans D (1989) Influence of viscosity and surfactant on Assure penetration of dental fluoride gels in vitro. Int J Pharm 49 147-156... 

It is likely that most small children swallow some of the paste and this possibility should be considered when fluoride tablets are prescribed due to the dangers of an excessive dose (page 147). Topical application may also be carried out by dentists and dental auxiliaries using acidic phosphate-fluoride gels applied to the tooth surface for several minutes. A low pH value is needed to drive the reaction... 

Dejneka M., Snitzer E., Riman R.E. Spectroscopic characterization of Eu " "-doped inorganic and alkoxide sol-gel derived fluorozirconate glass and zirconium fluoride gels. J. Non-Cryst. Solids... 

Different spectroscopic, microscopic and diffraction methods like IR and Raman spectroscopy, TEM or XRD were applied to characterize educts, intermediates or products of the sol-gel process. For a detailed insight into the mechanism of the fluorolytic sol-gel process, however, the application of NMR spectroscopy is the method of choice. The NMR experiments, both in liquid and in solid state, allow direct observations of local structures and their changes even if the matrices suffer from a loss of lattice periodicity. For the fluorolytic so-gel process both liquid state NMR experiments were realized for the alkoxide solutions, sols and thin gels as well as solid state MAS NMR experiments for the alkoxide, dried alkoxide fluoride gels and high-surface fluorides including H,... 

Structure of Wet and Dry Aluminium Alkoxide Fluoride Gels AlF2.-iOiPrQ i -xiPrOH — A Comparison... 

Figure 1.16 3QMAS spectrum of the aluminium alkoxide fluoride gel (AI F— 1 3) acquired at 14.1 T (Reprinted with permission from [40] Copyright (2009) American Chemical Society.)... 

Table 2.3 Characteristics of the dry gel obtained by microwave treatment of an alkoxi-fluoride gel...

Adoption of a sol-gel method to optical fluoride materials started with inorganic fluoride glasses. At first, the sol-gel processing appeared rather challenging because fluoride gels were not known and little was known about the chemical reaction between fluorinating... 

Zhu, Y.S., Xiao, S.Y., Shi, Y, Yang, Y.Q., Wu, Y.P. 2013. A trilayer poly(vinylidene fluoride)/polyborate/poly(vinylidene fluoride) gel polymer electrolyte with good performance for lithium ion batteries. 1 7790-7797. 

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