FLUORIDATION BASIS AND ITS EFFECT ON ENAMEL

FLUORIDATION BASIS AND ITS EFFECT ON ENAMEL

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  FLUORIDATION BASIS ANDITS EFFECT ON ENAMEL A. Bilski April 19, 2019 Title: Fluoridation basis and its effect on enamel. Author: Adam Bilski, 2nd year of Dentistry, [email protected]
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  Keywords: Dentistry, teeth,fluoride, enamel, oral health, dental tissues, hydroxyapatite, fluorapatite, Fluorine is a chemical element with atomic number 9, symbolized as F. It is the most electronegative element of Mendeleev’s table of elements, which means that it attracts shared electrons the strongest, therefore is commonly considered as the most reactive element in the periodic table. Fluorine’s first registry reaches 1529, when it was described by a German mineralogist Georgius Agricola, a scientist, also called a “father of mineralogy”, who called it an additive lowering melting point of metals during smelting. He pinned it with the Latin name fluorés, however fluorine’s symbol F comes from a New Latin name fluorum. The element’s isolation was a great unsolved problem of inorganic chemistry for long, until it finally had place in 1886, when a French chemist Henri Moissan electrolyzed a solution of potassium hydrogen fluoride in hydrogen fluoride, and for that he received a Nobel Prize in chemistry in 1906, 2 months before his death. In 1986 a new method of isolating fluorine was shown at a conference, celebrating 100 years after Moissan’s discovery. It was shown by Dr. Karl O. Christe, and it was evolving fluorine at high yield and atmospheric pressure, and its reactions were: 2 KMnO4 + 2 KF + 10 HF + 3 H2O2 → 2 K2MnF6 + 8 H2O + 3 O2↑ 2 K2MnF6 + 4 SbF5 → 4 KSbF6 + 2 MnF3 + F2↑ Use of fluorine in dentistry is commonly named as use of fluoride, which is an inorganic, monoatomic ion symbolized as 𝐹− , as it is usually found as a part of other compounds, like fluoride salts and hydrofluoric acid, and not in its elementary form. Our exposure to these compounds can happen through dietary intake, respiration and fluoride supplements, although most commonly and related to multiple controversies – through fluoridated water. Thanks to all the discoveries connected with this element in 20th century we were able to observe a massive increase in dental health, because of more exposure to fluoride and its anti-cariogenic effect, by influencing the process of remineralization of enamel. Enamel is the hardest tissue in human body, present in teeth as the outermost layer, defining limits of the crown, derived from ectoderm. It varies in thickness, hardness and color in each individual. Having no blood nor nerve supply, its structure
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  is of crystallitesgathered in bundles, called prisms (or rods), that are approx. 6 μm in diameter, radiating from dentinoenamel junction (DEJ), having its origin in ameloblasts present there. Enamel’s chemical composition is roughly 96% inorganic, 4% organic and less than 1% water – if we were to describe it in a non-stoichiometric model, at constant value of partial CO2, pressure, 25, its formula would be: (Ca)4,56(Mg)0,03(Na)0,11(HPO4)0,10(CO3)0,23(PO4)2,66(OH,F)0,65 with Ks = 8,5 (0,9) x 10-49 (Aoba T, Oral Diseases 10, 249-257 (2004)) The inorganic part of enamel is composed of calcium and phosphate ions, making up hydroxyapatite crystals (Ca10(PO4)6(OH)2), placed on fibrous structures, formed by amelogenin and enamelin proteins, which act as matrices for crystallization of hydroxyapatite. These crystals, making up most of the enamel as well as other hard tissues of human organism, are the main target of fluoridation. The process of fluoridation dates back to 1909, when a research on “something” staining teeth brown, but also improving their resistance to dental caries, started by Frederick McKay, later joined by Dr G. V. Black and H.V. Churchill. In January, 1931 this “something” turned out to be fluoride, and that discovery became a great step forward for modern preventive dentistry. Nowadays research on fluoride has already proven its mechanism of reducing dental decay, by inhibiting demineralization and promoting remineralization of affected enamel. Fluoride is present in our everyday lives, mainly in dental products like toothpaste, but also in our diet, in foods like black tea (3-5 mg/L) or chips (0,7 mg/L) (tab. 1). Its application can be either topical (directly on teeth in dental office or home) or systemic (digested in diet or as pills). Fluoride’s presence in water is also an important factor (systemic) as it is present there naturally, but can also be specifically enriched in fluoride in certain countries for the cause of lowering the community average caries development. When it comes to fluoride coming from diet – after consumption around 90% of fluoride is absorbed in the gastrointestinal tract and 10% is lost with fecies. After around 20-60 minutes the concentration of fluoride ions in blood is at its most (max. 0,06 ppm in physiological conditions), having bounded to plasma protein. Retention of fluoride is around 36% in adults and around 50% in children, bringing us to the conclusion of how important it is to receive this element in early years of life.
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  The mechanism offluoridation is theoretically simple – in hydroxyapatite crystals hydroxide ions are substituted by more electronegative, more reactive element – fluoride, thus hydroxyapatite becomes fluorapatite, which is stronger and more resistant to acidic conditions, created by bacteria of caries lesions. Fluoride’s effectiveness is visible during longer periods of its presence in oral cavity, longer than teeth brushing time, therefore the goal of dental products (for both topical and systemic fluoridation methods) is to place it in the oral cavity for a briefly undefined time, enough for it to be deposited and released over a certain period. Compounds containing fluoride, present in dental products are usually amine fluoride, sodium monofluorophosphate (Na2PO3F), stannous fluoride (SnF2) and olaflur (an organic salt) and most commonly – sodium fluoride (NaF). As it can be visible under an Energy-Dispersive-X-Ray-Spectroscopy (EDS/EDX) - fluoride from these molecules, along with calcium present in saliva, forms calcium fluoride (CaF2), which slowly releases fluoride, which then reacts with superficial layer of hydroxyapatite crystals present on demineralized enamel surface, created because of hypersaturation of Ca and P ions on the surface, that came from dissolution of the crystals during the decay process of caries lesion. To explain the basis to the process above - pH of oral cavity environment (saliva) is lowered by lactic acid being produced by bacteria such as S. Mutans, as a result of their sugar metabolism. Critical level of pH of hydroxyapatite is 5,5 and when pH of oral cavity is lower – demineralization process starts. If it’s caught in its early, reversible stage (for example by fluoride ions bounded to proteins in dental plaque), it will be stopped from enamel crystals dissolution, and when the pH rises again above 5,5 – process of remineralization will take place. What is interesting is that if the process above repeats, the new layer of remineralized enamel will be more resistant to acidic pH, as critical level of pH of the newly formed crystals can reach as low as even 4,5. Potential fluoride toxicity comes from the possibility of easy ingestion of fluoride-rich products like toothpaste (the most frequent source – 68% of cases), but also mouth washes (17%) and supplements (15%) (data collected by the American Association of Poison Control – AAPC). 80% of cases of the toxicity was reported by children up to 9 years old, because of their not fully developed gag reflex as well as their voluntary swallowing of the dental products based on their appealing taste.
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  Table 2. presentssummary of the important doses of fluoride and table 3 - summary of treatment protocol for fluoride overdose. As svíčková sauce has to go with knedliky, healthy teeth have to be associated with fluoride, and have been for hundreds of years already. Although we have to remember its deficiency does not cause caries and its presence does not reverse its development, its positive effect has been proven well enough for humans to know that this field is a necessity for the future of preventive dentistry and with modern technology of medicine and biochemistry we can work to eliminate the possible risks of the easy accessibility to ingest toxic quantities of this enamel- improving ion. References: 1. T. Aoba, 17 August 2004, “Solubility properties of human tooth mineral and pathogenesis of dental caries”, Oral Diseases, Volume 10, Number 5, September 2004, pp. 249-257(9) 2. Anonymous, https://en.wikipedia.org/wiki/Fluorine#History, 2019, read 27.03.2019 3. Anonymous, https://en.wikipedia.org/wiki/Fluoride, 2019, read 3.04.2019 4. Anonymous, https://en.wikipedia.org/wiki/Toothpaste#Fluorides, 2019, read 3.04.2019 5. Anonymous, https://www.nidcr.nih.gov/health-info/fluoride/the-story-of- fluoridation, July 2018, read 27.03.2019 6. W. H. Arnold, A. Dorow, S. Langenhorst, Z Gintner, J. Bánóczy and P. Gaengler, (2006), “Effect of fluoride toothpastes on enamel demineralization”, BMC Oral Health 2006 6: 8. 7. K. Christe, S. Schneider, https://www.britannica.com/science/fluorine, 1998, read 27.03.2019 The Editors of Encyclopedia Britannica, https://www.britannica.com/science/enamel-tooth, 1998, read 27.03.2019 8. J. Emsley, “The Elements”, 3rd edition. Oxford: Clarendon Press, 1998 9. D. Kanduti, P. Šterbenk, B. Artnik, (2016), “FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH”, Mater Sociomed, 28(2): 133-137 10.MOCA Author, https://carta.anthropogeny.org/moca/topics/enamel-structure- and-enamel-thickness,
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  Table 1. Fluorideconcentrations for different types of food. Source: United States Agriculture Department (USDA), 2005 Table 2. Summary of the important doses of fluoride. Important doses of fluoride Optimal dose of fluoride (for children & adults) 0.05 - 0.07 mg F/kg body weight Toxic dose of fluoride (for children & adults) 5 mg F/kg body weight Lethal dose of fluoride (children) 16 mg F/kg body weight
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  Important doses offluoride Lethal dose of fluoride (adults) 32 mg F/kg body weight Sources for Table 2.: Martínez-Mier EA. Fluoride:its metabolism, toxicity, and role in dental health. J Evid Based Complement Alternat Med. World Health Organization. Basic methods for assessment of renal fluoride excretion in community prevention programmes for oral health. Geneva: World Health Organization; 2014. Fluoride intake of children: considerations for dental caries and dental fluorosis. Buzalaf MA, Levy SM Monogr Oral Sci. 2011; 22():1-19. Table 3. Summary of treatment protocol for fluoride overdose. Fluoride/kilogram body weight* Treatment < 5.0 mg/kg 1.Oral administration of soluble calcium (milk) to relieve GIT symptoms 2.Observe for a few hours 3.Induced vomiting not required
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  Fluoride/kilogram body weight* Treatment > 5mg/kg 1.Require hospital admission 2.Use emetic to empty the stomach. However, if the patient has depressed gag reflex for instance in the case of babies (<6 months old), Down’s syndrome, or mental retardation, endotracheal intubation should be performed before gastric lavage. 3.Oral administration of soluble calcium (e.g. milk, calcium lactate, or gluconate solution). 4. Keep under observation for a few hours.
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  Fluoride/kilogram body weight* Treatment >15 mg/kg 1.Immediatehospital admission 2.Immediate stomach emptying and gastric lavage 3.Begin cardiac monitoring and be prepared for cardiac arrhythmias 4.Intravenous administration of 10% calcium gluconate solution 5.Electrolytes (calcium and potassium) should be monitored and corrected as required 6.Maintenance of adequate urine output by diuretics if required 7.General supportive measures for shock Source for the table 3: Diagnosis and treatment of acute fluoride toxicity. Bayless JM, Tinanoff N J Am Dent Assoc. 1985 Feb; 110(2):209-11.