Fluoride retention

I. Zipkin, F.J. McClure, Complex fluorides, caries reduction and fluoride retention in bones and teeth of white rats. Public Health Rep. 66 (1951) 1523-1532. 

Duckworth RM, Morgan SN Oral fluoride retention after use of fluoride dentifrices. Caries Res 1991 25 123-129. 

Zero DT, Raubertas RF, Pedersen AM, Fu J, Hayes AL, Featherstone JDB Studies of fluoride retention by oral soft tissues after the application of home-use topical fluorides. J Dent Res 1992 71 1546-1552. 

Kalo K, Nakagaki H, Arai K, Pearce EIF The influence of salivary variables on fluoride retention in dental plaque exposed to a mineral-enriching solution. Caries Res 2002 36 58-63. 

Vogel GL, Zhang Z, Chow LC, Schumacher GE Changes in lactate and other ions in plaque and saliva after a fluoride rinse and subsequent sucrose administration. Caries Res 2002 36 44-52. Duckworth RM, Morgan SN Oral fluoride retention after use of fluoride dentifrices. Caries Res 1991 25 123-129. 

An exact quantification of fluoride is possible if the advantage of simultaneous analysis is eliminated, and if the chromatographic conditions are changed in the way that fluoride is separated from the carbonate and bicarbonate traveling with the mobile phase. An increase in fluoride retention is achieved by using an eluent of lower elution strength. A dilute solution of sodium tetraborate is particularly suited in this respect. 

Salivary clearance from different regions of the mouth. 2) Salivary clearance in children with complete paimaiy dentitions. 3) Influence of the location of the parotid duct orifice on oral clearance. 4) Effect of saUvaiy flow rate on fluoride retention in the mouth. 5) Estimation of the velocity of the saUvaiy film at different locations in the mouth. 

Effect of salivary flow rate on fluoride retention in the mouth 2.4.1 Aim... 

Salivary clearance rates in different parts of the mouth are known to vary. The clearance half-times on the buccal surfaces of the upper anterior teeth were the longest of any site in the mouth. These show that the saliva secreted into the oral cavity is not perfectly mixed. Weatherell et al (1986) reports the difference by the fluoride distribution in the mouth after fluoride rinsing. Duckworth and Morgan (1991) and Heath et al. (2001) have also reported oral fluoride retention after use of fluoride rinse. These researches demonstrate the mechanism of the salivary clearance reported by Dawes (1983). According to Lear et al (1965), the salivary flow rate in the sleep is almost similar to the zero, but there are few reports the clearance of the fluoride in the sleep. 

Table 3 showed the comparison of the mean volume of fluoride retention at 6 30 am when the subjects had been sleeping. The fluoride concentrations were expressed as a percentage of that of the initial agarose which did not expose to saliva in the mouth. The values in LAL were also lowest, and UAB were highest. There were significant differences between the LAL and UAB (p<0.05) and between the LAL and UPB (p<0.05). 

Table 3. The mean volume (%) of fluoride retention at 6 30 a.m. when the subject had been sleeping...

Caries inhibition resulting from daily administration of chewable tablets or mouth rinses may be due to incorporation of absorbable fluoride into the developing enamel teeth surfaces. The retention of fluoride following oral rinses [311, 315, 336] or tablet chewing [336] has been followed by analysing the fluoride of the oral expectorates. The anti-caries effect of ionic fluoride might then be evaluated in relation to fluoride retention [311]. Perkins found oral retentions of 41, 20 and 7 per cent of the fluoride dose, respectively, administered as... 

The enrichment program followed in the United States is (/) the enrichment of flour, bread, and degerminated and white rice using thiamin [59-43-8] C 2H y N O S, riboflavin [83-88-5] C2yH2QN4Na02P, niacin [59-67-6] CgH N02, and iron [7439-89-6]-, (2) the retention or restoration of thiamin, riboflavin, niacin, and iron in processed food cereals (J) the addition of vitamin D [67-97-0] to milk, fluid skimmed milk, and nonfat dry milk (4) the addition of vitamin A [68-26-8], C2qH2qO, to margarine, fluid skimmed milk, and nonfat dry milk (5) the addition of iodine [7553-56-2] to table salt and (6) the addition of fluoride [16984-48-8] to areas in which the water supply has a low fluoride content (74). 

Calculate the daily fluoride intake of a dairy animal from (a) air and (b) food and water, based on the conditions below and assuming 100% retention of the fluoride ... 

During electrochemical fluorination retention of important functional groups or atoms in molecules is essential. Acyl fluorides and chlorides, but not carboxylic acids and anhydrides (which decarboxylate), survive perfluorination to the perfluorinated acid fluorides, albeit with some cyclization in longer chain (>C4) species [73]. Electrochemical fluorination of acetyl fluoride produces perfluoro-acetyl fluoride in 36-45% yields [85]. Electrochemical fluorination of octanoyl chloride results in perfluorinated cyclic ethers as well as perfluorinated octanoyl fluonde. Cyclization decreases as initial substrate concentration increases and has been linked to hydrogen-bonded onium polycations [73]. Cyclization is a common phenomenon involving longer (>C4) and branched chains. a-Alkyl-substituted carboxylic acid chlorides, fluorides, and methyl esters produce both the perfluorinated cyclic five- and six-membered ring ethers as well as the perfluorinated acid... 

From 3-0-acetyl-5-deoxy-5-iodo-1,2-0-isopropylidene-/ -l-ara-binofuranose (38). Treating 100 mg. of (38) in pyridine (1 ml.), with anhydrous silver fluoride (200 mg.) for 4 hours and isolating the product as described above afforded crystalline 34 in 87% yield. Pure material had m.p. 31°-33°C. and [ ]D24 — 6.5° (c, 4 in acetone). Both samples had identical infrared spectra and had the same g.l.c. retention time at 100°C. 

The reactions of a-methyl-branched acylsilanes with 2-propenylmagnesium bromide exhibit surprisingly high diastereoselectivilies, although further improvement is accomplished by application of allyltrimethylsilane/ titanium(IV) chloride (> 100 I)27. The fluoride-induced desilylation proceeds with retention of configuration. 

This excellent method of oxidative cleavage (/) of carbon-silicon bonds requires that the silane carry an electronegative substituent (2), such as alkoxy or fluoro. Either hydrogen peroxide or mcpba may be used as oxidant, and the alcohol is produced with retention of configuration (3). Fluoride ion is normally a mandatory additive in what is believed to be a fluoride ion-assisted rearrangement of a silyl peroxide, as shown below ... 

Halide exchange, sometimes call the Finkelstein reaction, is an equilibrium process, but it is often possible to shift the equilibrium." The reaction is most often applied to the preparation of iodides and fluorides. Iodides can be prepared from chlorides or bromides by taking advantage of the fact that sodium iodide, but not the bromide or chloride, is soluble in acetone. When an alkyl chloride or bromide is treated with a solution of sodium iodide in acetone, the equilibrium is shifted by the precipitation of sodium chloride or bromide. Since the mechanism is Sn2, the reaction is much more successful for primary halides than for secondary or tertiary halides sodium iodide in acetone can be used as a test for primary bromides or chlorides. Tertiary chlorides can be converted to iodides by treatment with excess Nal in CS2, with ZnCl2 as catalyst. " Vinylic bromides give vinylic iodides with retention of configuration when treated with KI and a nickel bromide-zinc catalyst," or with KI and Cul in hot HMPA." ... 

Fluorination with retention of configuration (such as in 327) has often been attributed to steric crowding on the opposite side of the hydroxyl group, hindering the back side of the fluoride ion for Sn2 attack. However, a possible Sn/ mechanism by loss of an OSp2NEt2 fragment to give a car-bonium cation, followed by front-side attack of fluoride ion, should be... 

They react with a wide range of aliphatic and aromatic aldehydes in the presence of catalytic amounts of tetrabutylammonium fluoride (TBAF) to give the trialkylsilyl ethers of P-nitro alcohols with high anti-selectivity (98%). The diastereoselective Henry reaction is summarized in Table 3.2. The products are reduced to P-amino alcohols using Raney Ni-H2 with retention of the configuration of P-nitro alcohols (Scheme 3.12). 

In sharp contrast to the above mentioned conversions of 73a, its reaction with 0-ethyl thiophosphate is nonstereoselective (90% inversion and 10% retention). Moreover, with a fluoride anion, complete loss of stereochemistry was observed [60], An efficient synthesis of diastereomerically pure vinyl phosphonates lOOa-e was... 

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