Fluoride

Fluoride has long been known to influence the activity of various enzymes in vitro. Latterly it has been demonstrated that many effects primarily attributed to fluoride are caused by a synergistic action of fluoride plus aluminum. Fluorinated chemicals are of growing importance, with applications in medicine. Fluorine substitution has profound effects on the properties of organic compounds. The very high electronegativity of fluorine can modify electron distribution in the molecule, affecting its absorption, distribution and metabolism. Fluorine-containing drugs are used in medicine as anesthetics, antibiotics, anti-cancer and anti-inflammatory agents, psychopharmaceuticals, and in many other applications. The potential contribution of fluorinating pharmaceuticals to human fluoride exposure is discussed.

“A Bayesian survival analysis is presented to examine the effect of fluoride-intake on the time to caries development of the permanent first molars in children between 7 and 12 years of age using a longitudinal study conducted in Flanders. Three problems needed to be addressed. Firstly, since the emergence time of a tooth and the time it experiences caries were recorded yearly, the time to caries is doubly interval censored. Secondly, due to the setup of the study, many emergence times were left-censored. Thirdly, events on teeth of the same child are dependent. Our Bayesian analysis is a modified version of the intensity model of Härkänenet al. (2000, Scandinavian Journal of Statistics 27, 577–588). To tackle the problem of the large number of left-censored observations a similar Finnish data set was introduced. Our analysis shows no convincing effect of fluoride-intake on caries development. “

“Common environmental chemicals, drugs, or physical agents can adversely affect human teeth during their embryonic development and after their eruption into the oral cavity. One of the more common elemental toxicants is lead. Teeth are known to accumulate lead during their development. Both animal and human studies have shown that teeth with high lead levels are generally more susceptible to dental caries. Similarly, although inorganic fluorides have long been recognized for their potential to prevent dental caries, exposure to excessive amounts of fluoride when enamel is forming often leads to a type of enamel hypoplasia referred to as dental fluorosis or mottled enamel. Teratogenic agents, such as tetracyclines, a class of antibiotic drugs commonly administered to infants and children, will often result in the discoloration of tooth enamel when prescribed during tooth development. It has recently been suggested that childhood exposure to passive smoking increases the risk for dental caries. Environmental tobacco smoke has previously been linked to periodontal disease in adults. However, this is the first report of an association between passive tobacco smoke and increased susceptibility to dental caries. Last, an often-overlooked source of damage to teeth among all age groups after their eruption into the oral cavity is physical trauma from a variety of sources, especially sports-related injuries. Epidemiologic data suggest that up to one third of all dental injuries are sports related.”

Although potential toxic effects of sodium fluoride on early pro-genitor and stem cells have been reported previously, surprisingly few inves-tigations have examined the effects of fluoride on human leukemic cells. To address this need, four different human leukemic cell lines (HL-60, HEL, TF-1, and K562) were exposed to increasing levels (0, 0.24, and 1.19 mM F) of two forms of fluoride: sodium fluoride (NaF) and sodium hexafluorosilicate (Na2SiF6). Because of its widespread use in water fluoridation, Na2SiF6 was investigated in addition to NaF.  The early response effect of Na2SiF6 was greater, and in several cases significantly greater, than NaF on clonogenic growth and the induction of apoptosis in all four cell lines.  These findings show that human leukemic cells can be influenced and damaged by fluorine compounds.

The Intelligence Quotient (IQ) was measured in 512 children, aged 8–13 years, living in two villages in Sihong County, Jiangsu Province, China, differing in the level of fluoride in their drinking water. In the high-fluoride village of Wamiao (water fluoride: 2.47±0.79 mg/L; range: 0.57–4.50 mg/L), the mean IQ of 222 children was significantly lower (92.02±13.00; range: 54–126) than in the low-fluoride village of Xinhuai (water fluoride: 0.36±0.15 mg/L; range: 0.18–0.76 mg/L), where the mean IQ of 290 children was higher (100.41±13.21; range: 60–128). The children’s IQs were not related to urinary iodine, family income, or parent’s education level. Higher drinking water fluoride levels were significantly associated with higher rates of mental retardation (IQ <70) and borderline intelligence (IQ 70–79). The Benchmark Concentration (BMC) for the concentration-response relationship between IQ <80 and the drinking water fluoride level was 2.32 mg/L, and the lower-bound confidence limit (BMCL) of the BMC was 1.85 mg/L. Taking dental fluorosis and other sources of dietary fluoride into account, the reference value con-centration (RfC) for fluoride was calculated to be 0.925 mg/L, which is very close to the current national Chinese standard of <1.0 mg/L. In endemic fluo-rosis areas, drinking water fluoride levels greater than 1.0 mg/L may adversely affect the development of children’s intelligence.

“Fluoride is a well-known G protein activator. Activation of heterotrimeric GTP-binding proteins by fluoride requires trace amounts of Al3+ or Be2+ ions. AlFx mimics a γ-phosphate at its transition state in a Gα  protein and is therefore able to inhibit its GTPase activity. AlFx also forms complexes with small GTP-binding proteins in the presence of their GTPase-activating proteins (GAP). As phosphate analogs, AlFx or BeFx affect the activity of a variety of phosphoryl transfer enzymes. Most of these enzymes are fundamentally important in cell signal transduction or energy metabolism. Al3+ and F- tend to form stable complexes in aqueous solution. The exact structure and concentration of AlFx depend on the pH and the amount of F- and Al3+ in the solution. Humans are exposed to both F and Al. It is possible that Al-F complexes may be formed in vivo, or formed in vitro prior to their intake by humans. Al-F complexes may play physiological or pathological roles in bone biology, fluorosis, neurotoxicity, and oral diseases such as dental caries and periodontal disease. The aim of this review is to discuss the basic chemical, biochemical, and toxicological properties of metallic fluoride, to explore its potential physiological and clinical implications. “

“Social scientists who dismiss evolutionary psychology seem unaware that a revolution in neuroscience and other areas of biology has taken place over the last halfcentury. The estimate of 83 million Americans taking drugs like Prozac for depression and 11 million children on Ritalin for hyperactivity indicate it is time to reconsider the role of brain chemistry in social behavior and violent behavior. As evolutionary psychology demonstrates, aggressive impulses are an integral part of the primate behavioral repertoire. Since it is obvious that loss of impulse control can contribute to violent outbursts and evidence shows that some toxic chemicals (such as lead) can have this effect, it is time to consider neuroscientific evidence linking environmental toxins and rates of violent behavior.”

The quality of environment that human society had in the beginning of the twentieth century was far better than what has been handed over to the mankind of the first century of the new millennium. On account of ruthless development activities and over exploitation of natural resources, several animate and inanimate objects of the nature have either lost their quality or had perished. This has necessitated that people should learn more about the environment and educate themselves to protect it from further degradation and destruction, not only in terms of human health and welfare, but also in perspective of safety of other living and non-living constituents of the environment.

This study evaluated fluoride-release and recharging with the fluoride mouth rinsing technique on fluoridated materials. Three fluoride containing materials and one non-fluoride containing composite resin were used for this study. Samples for each material consisted of 15 discs, 9 mm diameter with a thickness of 1 mm. Initial fluoride release was assessed over a 60-day period. After that, 15 discs for each material were divided into 3 groups: distilled water group, 450-ppm and 900-ppm mouth rinsing groups. Fluoride release increased in combination with fluoride mouth rinse, and fluoride was higher in the 900-ppm group than the 450-ppm group. Moreover, S-PRG or F-PRG fillers materials released fluoride in higher than fluoroaluminosilicate glass fillers materials. In addition fluoride release from control samples was not observed. Therefore, only fluoride release material takes up fluoride. The findings of the present investigation suggest that the rate of fluoride release was different for each material, because they contained different function fillers. The results showed the importance of the fluoride mouth rinsing technique for fluoride-releasing restorative materials for the prevention of secondary caries.

One of the most important and exciting properties of recently introduced dental restorative materials is their ability to release fluoride ions, as this has several advantageous effects on tooth structures. They have been extensively used as fluoride-releasing filling and luting materials. Recently, fluoride-releasing adhesive resins and fluoride-releasing adhesive resin cement have been developed and introduced for clinical use. The purpose of this study was to evaluate the fluoride release from these adhesive resins and the fluoride uptake by both enamel and dentin, as well as the acid-resistance of these tooth structures. Based on our results, we conclude that fluoride-releasing adhesive resins and luting cements are useful for the prevention of initial or secondary caries, especially along the margins of restorations.