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  1. 1. 1 | P a g e Chapter 1: Introduction Fluorine is a common element that does not occur in the elemental state in nature because of its high reactivity. It accounts for about 0.3 g/kg of the Earth’s crust and exists in the form of fluorides in a number of minerals, of which fluorspar, cryolite Physicochemical properties Hydrogen fluoride (HF) is a colourless, pungent liquid or gas with a boiling point of 19.5 °C. It is highly soluble in water, in which it forms hydrofluoric acid. Sodium fluoride (NaF) is a colourless to white solid that is moderately soluble in water. Fluorosilicic acid (H2SiF6), which is also known as hexafluorosilicic acid, is a colourless solid that is highly soluble in water. And fluorapatite are the most common. The oxidation state of the fluoride ion is -1. Major uses Inorganic fluorine compounds are used in industry for a wide range of purposes. They are used in aluminium production and as a flux in the steel and glass fibre industries. They can also be released to the environment during the production of phosphate fertilizers (which contain an average of 3.8% fluorine), bricks, tiles and ceramics. Fluorosilicic acid, sodium hexafluorosilicate and sodium fluoride are used in municipal water fluoridation schemes also sodium monoflourophosphate are used in manufacturing of toothpaste. In the human body, fluoride is mainly associated with bones and teeth. It plays an important role in the prevention of dental caries. Although the primary mechanism
  2. 2. 2 | P a g e of action of fluoride in preventing dental caries is topical, systemic mechanisms are also important. Fluoride acts in the following ways to prevent dental caries: 1. It enhances remineralization of the tooth enamel. This is the most important effect of fluoride in caries prevention. 2. It inhibits demineralization of the tooth enamel. Mineral structure of the tooth that includes fluoride (fluorapatite) is more resistant to demineralization than one without fluoride (hydroxyapatite). 3. It makes cariogenic bacteria less able to produce acid from carbohydrates. Fluoride Facts Fluoride has been available in the United States since the mid-1940. In 2008, 64.3% of the population served by public water systems received optimally fluoridated water. Public water fluoridation practice varies by city and state. Water fluoridation was recognized by the Centers for Disease Control and Prevention (CDC) as one of the 10 greatest public health achievements of the 20th century. There is strong evidence that community water fluoridation is effective in preventing dental caries. The recommended concentration of fluoride in drinking water was decreased in 2011 from 0.7-1.2 mg/L to 0.7 mg/L.Clinicians should balance the benefits of fluoride against the risk of fluorosis when deciding whether to fluoridate water. Water filters may decrease the fluoride content of community water. Activated charcoal filters and cellulose filters have a negligible effect; reverse osmosis filters and water distillation remove almost all fluoride from water.
  3. 3. 3 | P a g e Chapter 2: Occurrence and sources Many fluoride minerals are known, but of paramount commercial importance is fluorite. It is composed of calcium fluoride, with small impurities. The soft, colorful mineral is found worldwide and is common. In seawater, fluoride concentration averages 1.3 parts per million (ppm). For comparison, chloride concentration in seawater is about 19,000 ppm. The low concentration of fluoride reflects the insolubility of the alkaline earth fluorides, e.g., CaF2. Fluorite crystals Sources of fluoride Systemic Sources of Fluoride Fluoride can be ingested through Drinking water Traces of fluorides are present in many waters; higher concentrations are often associated with underground sources. In seawater, a total fluoride concentration of 1.3 mg/litre has been reported (Slooff et al., 1988). In areas rich in fluoride containing minerals, well water may contain up to about 10 mg of fluoride per litre. The highest natural level reported is 2800 mg/litre. Fluorides may also enter a
  4. 4. 4 | P a g e river as a result of industrial discharges (Slooff et al., 1988). In groundwater, fluoride concentrations vary with the type of rock the water flows through but do not usually exceed 10 mg/litre. In bottled water, no one source exists to tell consumers the fluoride content in bottled waters. The US Food and Drug Administration (FDA) does not require that fluoride content be listed on the labels of bottled waters. It is appropriate to assume that children whose only source of water is bottled are not receiving adequate amounts of fluoride from that source. Food Virtually all foodstuffs contain at least traces of fluorine. All vegetation contains some fluoride, which is absorbed from soil and water. The highest levels in field grown vegetables are found in curly kale (up to 40 mg/kg fresh weight) and endive (0.3–2.8 mg/kg fresh weight). Other foods containing high levels include fish (0.1– 30 mg/kg) and tea. High concentrations in tea can be caused by high natural concentrations in tea plants or by the use of additives during growth or fermentation. Levels in dry tea can be 3–300 mg/kg (average 100 mg/kg), so 2–3 cups of tea contain approximately 0.4–0.8 mg. In areas where water with high fluoride content is used to prepare tea, the intake via tea can be several times greater. Infant nutrition. Human breast milk contains almost no fluoride, even when the nursing mother drinks fluoridated water. Powdered infant formula contains little or no fluoride, unless mixed with fluoridated water. The amount of fluoride ingested will depend on the volume of fluoridated water mixed with the formula.
  5. 5. 5 | P a g e Fluoride Supplements Supplements should be considered especially for patients at high risk for dental caries whose community water source is suboptimal. Supplements are available in liquid, tablet, or lozenge form. N.B: 0.25–1 mg per tablet; The 2010 ADA guideline recommends fluoride supplements be prescribed only to children at high risk for caries development. The United States Preventive Services Task Force recommends fluoride supplementation be prescribed at recommended doses to children older than 6 months whose primary water source is deficient in fluoride Topical Sources of Fluoride Toothpaste Toothpaste is the most recognizable source of topical fluoride. The addition of fluoride to toothpaste began in the 1950s. Brushing with fluoridated toothpaste is associated with a 24% reduction in decayed, missing, and filled tooth surfaces. A recent review by the Cochrane Collaboration concluded that regular use of fluoridated toothpaste is associated with a “clear reduction in caries increment.” Fluoride Mouthrinses Mouthrinses containing fluoride are recommended in a “swish and spit” manner.
  6. 6. 6 | P a g e Mouthrinses are available over the counter. Frequency of use ranges from daily to weekly. According to the Cochrane Collaboration, regular fluoride mouthrinses use reduces tooth decay in children, regardless of other fluoride sources, with an average 26% reduction in decayed, missing, and filled tooth surfaces. Fluoride mouthrinse programs are sometimes utilized in schools. Fluoride Gels Fluoride gels are professionally applied or prescribed for home use under professional supervision. They are typically recommended for use twice per year. The gel is placed in two trays (one tray for the upper teeth, and one tray for the bottom teeth), which are then placed in the patient’s mouth. The patient is then asked to bite down on the trays for 4 minutes. Due to the high acidity of the gel (pH 3.5), saliva flow is markedly increased during the course of the treatment, thus increasing the percentage of the gel that is ingested. The high acidity also enables the fluoride to cross directly through the gum membrane When scientists discovered in the 1980s the enormous spikes in blood fluoride levels that occur after fluoride gel treatment (see below), the dental community implemented measures to reduce the amount of fluoride ingested from the gel
  7. 7. 7 | P a g e These measures include: A. ensuring that the patient is sitting upright B. reducing the amount of gel used for young children; C. placing a suction device in the mouth during the course of the treatment to vacuum out the excess saliva; and D. encouraging the patient to spit (i.e., expectorate) for up to one minute when the trays are removed from the mouth Fluoride Varnish Varnishes are a professionally applied, sticky resin of highly concentrated fluoride (up to 22,600 ppm). In the United States, fluoride varnish has been approved by the FDA for use as a cavity liner and root desensitizer, but not specifically as an anti-caries agent. For caries prevention, fluoride varnish is an “off label” product. Varnishes have been used extensively in Europe, Scandinavia, and Canada as preventive intervention for dental caries. Application frequency for fluoride varnish ranges from 2 to 6 times per year. The use of fluoride varnish leads to a 33% reduction in decayed, missing, and filled tooth surfaces in the primary teeth and a 46% reduction in the permanent teeth.
  8. 8. 8 | P a g e Chapter 3: Community Water Fluoridation and Deflouridation. The goal of community water fluoridation is to maximize dental caries prevention while minimizing the frequency of enamel fluorosis. A 1994 World Health Organization expert committee suggested a level of fluoride from 0.5 to 1.0 mg/L (milligrams per litre), depending on climate. Bottled water typically has unknown fluoride levels, and some domestic water filters remove some or all fluoride. Defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits especially for our country which reported to have exceeded amount. Common methods of Defluoridation are  Synthetic ion exchange  reverse osmosis and  Nalgonda Technique Nalgonda Technique This technique most used in our country for deflouridation. The Nalgonda technique is a means of fluoride removal that depends on the flocculation, sedimentation, and filtration of fluoride with the addition of aluminum sulfate and lime. This technique was developed by the National Environmental Engineering Research Institute in India in 1975 in response to fluorosis concerns. Aluminum sulfate (Al2 (SO4)318H2O) is added to the water to acts as a flocculent. Though aluminum sulfate is commonly used in general water treatment as a flocculent, the amounts used in defluoridation are much higher (150 mg/mgF or 1000mg/L or 20 times normal). As is typical with flocculation processes, the water must be thoroughly stirred to ensure dispersal of the flocculating agent. Because the reaction results in an excess of H+ ions, Lime (Ca (OH)2) is added to the water during the process to help maintain a neutral pH and hasten the settling of the sediment. The amount of lime added is typically 5% (by mass) of the aluminum sulfate added though some sources say significantly more (20-50% of alum by mass) should be added. The chemical processes, though admittedly are not fully understood
  9. 9. 9 | P a g e A possible home set up for implementing the Nalgonda technique. Reverse Osmosis Reverse osmosis is a technology that has been used more successfully in the developed world than the developing world. This process is achieved by applying high pressure to water against a semi permeable membrane that is capable of rejecting undesired ions from passing through. A variation of this process is known as electrodialysis that relies on DC potential to remove specific ions. In fact, reverse osmosis can be used to remove a variety of undesired quantities from the water depending on the nature of the membrane used. Being a purely physical process, it eliminates many of the problems seen with other defluoridation techniques, like pH balancing and the need for regeneration. Reverse Osmosis has been shown to successfully treat water with fluoride concentrations up to 12 mg/L. Unfortunately, reverse osmosis has not been successfully implemented in the developing world for a number of reasons. The primary being that it is a very costly defluoridation option. Additionally, reverse osmosis requires much electrical power to operate. Also, 20-40% of water is lost in this treatment process, possibly much more. Technological improvements in materials and larger scale operations may someday make this technology affordable to more people in need of defluoridation technology
  10. 10. 10 | P a g e Synthetic ion exchange. There are a number of strong base anion exchangers that are able to perform an ion exchange process to remove fluoride from water, typically exchanging for chloride ions. Many of these are not specifically designed for use in removing fluoride, but rather all anions. Thus because they are not specifically designed for removing fluoride, their actually fluoride removal capacities are relatively low. Though able to be regenerated with the use of chloride salts, they are not necessarily the most economical and available in areas where they are not produced, and thus, at this point, are not able to really be considered an alternative in the developing world
  11. 11. 11 | P a g e Chapter 4: KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS After oral uptake, water-soluble fluorides are rapidly and almost completely absorbed in the gastrointestinal tract. Absorbed fluoride is transported via the blood; with prolonged intake of fluoride from drinking-water, concentrations in the blood are the same as those in drinking-water, a relationship that remains valid up to a concentration in drinking-water of 10 mg/litre. Distribution of fluoride is a rapid process. It is incorporated into teeth and bones; there is virtually no storage in in soft tissues. Incorporation into teeth and skeletal tissues is reversible: after cessation of exposure, mobilization from these tissues takes place. Fluoride is excreted via urine, faeces and sweat (IPCS, 1984; US EPA, 1985a; Janssen et al., 1988). Fluoride in inhaled particles is also absorbed, the extent of absorption depending on the size of the particles and the solubility of fluoride compounds present. Hazardous Fluorosis There are numerous fluoride “belts” throughout the world where groundwater contain unsafe levels of fluoride. These belts span over 14 countries in Africa, 8 countries in Asia, and 6 countries in the Americas that all having water considered unsafe by the World Health Organization (WHO) this may result in fluorosis .And fluorosis is caused by an increased intake of fluoride. There are general two categories which are:
  12. 12. 12 | P a g e Dental Fluorosis Dental fluorosis is by far the most common manifestation of over-consumption of fluoride. It is visible by white, yellow, and brown streaks on the teeth, characteristic of the hypoplasia and hypocalcification. This damage is more than cosmetic, as it tends to be associated with painful "cavity-like" feelings. Additionally, there are social stigmas against those suffering from fluorosis. It had once been postulated that men were more disposed to suffering from dental fluorosis than women, however, it is now believed that this inference was incorrect, and that women are more likely to try to hide the effects of fluorosis. While all teeth are affected, the incisors (especially the maxillary incisors) and permanenet molars are often the teeth most affected by fluorosis. It is speculated that this is because these are the first teeth to develop. Normally dental fluorosis described as: check photograph bellow Mild forms of fluorosis appear as chalk-like, lacy markings on the tooth’s enamel. Moderate form of dental fluorosis, a white opacity can be seen on more than 50% of the tooth. Severe fluorosis results in brown, pitted, brittle enameluorosis
  13. 13. 13 | P a g e Skeletal Fluorosis Though it generally takes far more time, and higher concentrations (typically over 10mg/l) to develop, skeletal fluorosis is far more severe than its dental counterpart. Though not initially obvious to diagnose, skeletal fluorosis can be detected early on radiologically. Skeletal fluorosis is characterized by deformation of bone structure. Movement of the spine, pelvis, and joints become increasing arduous as fluoride deposits collect on ligaments and tendons and within the bones themselves. Skeletal fluorosis to the point of crippling is not uncommon. Skeletal fluorosis is non-curable, thus efforts should be directed toward prevention and attempting to alleviate some of the symptoms Neurological complications There are increasing accounts of the neurological affects that fluoride can have on the body. It is suspected that these complications are caused by fluorides effects on the spine and compression on the spinal cord. Studies have shown that high levels of fluoride can cause headaches, insomnia, and reductions in the IQs of children. Fluorosis has significant economic impacts in the developing world. In addition to fluorosis removing people from the workforce, water supply programs have thrown away significant finances while providing costly boreholes that become useless upon the discovery of the toxic levels of fluoride that they contain. Conclusion: Perceptions and Education on Fluoride and Fluorosis Because fluoride does not cause water to have any abnormal, taste, and odor, it is difficult to determine if water has significant fluoride concentrations. Because of this and the cumulative nature of fluoride as a toxin (that is, the results of
  14. 14. 14 | P a g e consumption are not immediate), many peoples do not automatically connect water consumption to fluorosis. The effects of the disease have been attributed to a wide range of sources by different peoples including genetics, infection, and diet. (One people group in Kenya believes that fluorosis is caused by eating of potatoes that are too hot.) Therefore, there is a great need for education on and awareness of fluorosis in fluorotic areas and to connect water consumption to the symptoms of fluorosis. In many of these areas, little priority is given to water defluoridation because water sources are scarce enough that peoples are not concerned with water quality. And because fluoride consumption has no immediate health effects and defluoridation methods are generally more time and money intensive than other water treatment types, there is generally a lack of motivation on the part of the people to be concerned with defluoridation. Even when defluoridation methods are used, the lack of immediate results is a hindrance in encouraging the continued use of defluoridation. References 1. American Academy of Pediatric Dentistry. Guideline on Infant Oral Health Care. Council on Clinical Affairs. Reference Manual 2011. 33(6): 124-128. 2. American Academy of Pediatric Dentistry. Policy on Early Childhood Caries (ECC): Classifications, Consequences, and Preventive Strategies. Pediatr Dent 2011, 33(6): 47-49. 3. American Dental Association Council on Scientific Affairs. Professionally applied topical fluoride. Evidence-based clinical recommendations. JADA. August 1, 2006. 137(8): 1151-1159. 4. Berg J, Gerweck C, Hujoel PP, et al. Evidence-Based Clinical Recommendations Regarding Fluoride Intake from Reconstituted Infant Formula and Enamel Fluorosis. A Report of the American Dental Association Council on Scientific Affairs. JAMA. January 2011 vol. 142(1): 79-87. 5. Centers for Disease Control and Prevention. Recommendations for using fluoride to prevent and control dental caries in the United States. MMWR. 2001; 50(RR-14): 1-42.