Systemic fluoride dr.huda


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fluoride mechanism and type of application

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Systemic fluoride dr.huda

  1. 1. Systemic FluorideIn prevention of dental cariesSystemic fluoride was used to prevent dental caries back toas early as 1874. Fluoride ions convert to [hydrofluoric acid](HF) at pH 1.0-2.0 in the gut and are rapidly absorbed. Nearlyall (99%) of retained Fluoride is incorporated into developingbones and teeth in the mineral, making the enamel crystalslarger and more stable&affecting the crown morphologymaking the pits and fissures shallower and hence less likelyto create stagnation areasBYDr.Marwa Laith Faris2/20/2011
  2. 2. Systemic FluoridesI ntroductionThe use of fluorides date back to as early as 1874 when the GermanErharde suggested the use of potassium fluoridetablets for expectantmothers and children in order to strengthen teeth. This recommendationwas without any scientific evidence. What we now know to be dentalfluorosis (mottling) was noted by dentists long ago, who reported on„Colorado Stain‟ without the etiology of the tooth defect beingestablished.M etabolism and absorptionFluoride ions convert to [hydrofluoric acid] (HF) at pH 1.0-2.0 in thegut and are rapidly absorbed. Approximately 50% of ingested Fluorideis excreted in the urine. A small amount is excreted in the feces, salivaand sweat. Serum Fluoride levels peak within 1 hour of ingestion andreturn to normal after approximately 3 to 5 hours. Fluoride accumulatesin patients with impaired kidney function and its retention is affected bythe acid-base balance: a diet rich in meat protein will producean acidicrenal filtrate and cause more Fluoride to be retained. Nearly all (99%) 1
  3. 3. of retained Fluoride is incorporated into developing bones and teeth inthe mineral.Fluoride exchanges with the hydroxyl groups of existing hydroxyapatitecrystals in bone to form fluorapatite (FA), which is less soluble in acid.Tooth enamel with more FA is more resistant to acid erosion fromdietary acids and the weak acids produced by oral bacteria that causedental decay. Similarly, FA in bone makes it more resistant toosteoclasts, which use protons to dissolve the mineral.M echanisms of Action of FluorideThe action of fluoride can give the following results:*It has an effect during tooth formation making the enamel crystalslarger and more stable;*It inhibits plaque bacteria by blocking the enzyme enolase duringglycolysis;*It inhibits demineralization when in solution;*It enhances remineralization by forming fluorapatite when in solution;*It affects the crown morphology making the pits and fissures shallowerand hence less likely to create stagnation areas. 2
  4. 4. The most important of these mechanisms is that, when fluoride ispresent in the oral environment at the time of the acid attack, it inhibitsdemineralization and promotes remineralization.The critical pH forapatite is 5.5 and below this the calcium and phosphate ions pass out ofthe enamel (demineralization). At pH = 7.0, apatite remineralizes and iffluoride is present at this time fluorapatite forms (remineralization).Fluorapatite is resistant to acid attack until the pH drops to 3.5.Therefore, it is most important to have an intra-oral source of fluoridewhen remineralization is taking place.In the past it was thought that thesystemic action of fluoride was important for caries prevention. Thisview has completelychanged and it is now known that it is the topicalaction of fluoride that is essential for caries prevention.It is the presence of fluoridein the liquid phase at the plaque-enamelinterface that is of most importance.Studieshave shown that evenlowlevels of fluoride (0.01 ppm) wereeffective in preventing thedissolutionof enamel. It has been stated that it isthe activity of thefluoride ion in the oralfluid that is important in reducing thesolubility ofthe enamel rather than ahigh content of fluoride in the enamel.Saliva, the fluid that bathes the teeth,has been extensively studied. Thelevelof fluoride in saliva is thought to beimportant for caries preventionand ithas been shown that subjectssusceptible to caries had salivary fluoride 3
  5. 5. levels of <0.02 ppm, whereascaries resistant subjects had levels of>0.04ppm.There are a vast number of fluorideproducts that are available forsystemicand topical use. Systemic fluoride can be described as follows:A -Water FluoridationThis is a systemic method of providingfluoride on a community basis. Over300million people worldwide receivenaturally or artificiallyfluoridatedwater. In 1942, Dean et al.showed 1.0ppm fluoride to be theoptimum level.This was in a pre-fluoride era andperhaps the optimum levelneeds to bereviewed. There have been 113 studies in 23 countries over thelast 50 years13showing that dental caries is reduced by50%. It is cheap andcost-effective but there are opponents to its use. In some countries schoolwater has been fluoridated, but a concentration of 5ppm is required to offsetthe less frequent intake.B - Fluoride SupplementsThese are in the form of:I-Tablets anddrops.Caries reductions vary from 20 - 80%.There isusually very poor patientcompliance, especially for high caries-riskgroups. A „Catch 22‟ situation is thecase in which those patients that 4
  6. 6. arecompliant do not need supplements,whereas those that will benefitwill nottake them.The doses vary worldwide and are being increasingly heldresponsiblefor the rise in fluorosis. Thefluoride supplement doses depend on theage of the patient and the level offluoride in the drinking water.Nosupplements should be prescribed if the water fluoride level isgreater than 0.7 ppm.The tablets should be allowed todissolve slowly in the mouth,thusproviding a topical application offluoride to the teeth. There are ofcourse other systemic methods for providingfluoride to the community.These are:II-Salt;50% reductions in Switzerland and Hungary;III-Milk;15–65% reductions;IV-Mineral Water;46% reductions in Bulgaria.The fluoride levels ofbottled waters vary considerably, from 0.0-2.0 ppm mainly, but can beas high as 10.0-13.0 ppm in some countries.V- Sugar;Luoma showed decreased caries levels in animals andhumans when fluoride was added to sugar. 5
  7. 7. There are, therefore, a number of sources of fluoride that we and ourpatients may be exposed to:*Water1.0 mg/day*Supplements1.0 mg/day*Diet0.5 mg/day*Toothpaste0.25 mg/day (in children)A dverse effect and toxicityC hronic ToxicityBefore prescribing fluoride supplements we must first determine thefluoride level of the patient‟s drinking water, the infant may be atincreased risk of developing dental fluorosis. The maxillary permanentcentral incisors are most susceptible to fluorosis at about 2 years of age.Dental fluorosis is a health condition caused by a child receiving toomuch fluoride during tooth development. The critical period ofexposure is between 1 and 4 years old; children over age 8 are not atrisk. In its mild form, which is the most common, fluorosis appears astiny white streaks or specks that are often unnoticeable. In its severest 6
  8. 8. form, which is also called mottling of dental enamel; it is characterizedby black and brown stains, as well as cracking and pitting of the teeth. Fig. 1; A mild case of dental fluorosis (the white streaks on the subjects upper right central incisor) observed in dental practice Fig 2; A severe case of dental fluorosis, or "mottled dental enamel." 7
  9. 9. The „Halo Effect‟ is the term used to describe the ingestion of fluoridefrom hidden sources. For example, fizzy drinks like Pepsi or Coca- colamay contain fluoride if the bottling plant is in a fluoridated area andtherefore uses fluoridated water.Other than dental fluorosis there are no known adverse effects ofingesting fluoride on chronic basis at levels that are associated withdrinking water of concentrations of 4 ppm or less. These levels of intakeinclude fluoride not only in water but also in diet and in fluoride-containg dental products.Studies have shown that fluoride causes various histologicalstructurechanges of the kidney, including extensive induction of cell apoptosis,resulting in impairment of renal function and metabolism, Fluorideinterferes with the formation of normal collagen, the protein cementwhich holds body structures together.Total collagen is increased, as much as 50% in one study, but thecollagen is imperfect. Structures heavily dependent upon collageninclude tooth enamel and dentin, bone, cartilage, and muscle and skin.Finally signs of skeletal fluorosis may appear with high levels withfluoride intake (8-10 ppm or higher in drinking water) forapproximately 10 years or more. 8
  10. 10. A cute ToxicityThe Probably Toxic Dose (PTD) was defined by Whitford as theminimum amount of fluoride ingestion that requires action, and is5mg/Kg body PTD for 1-2 year old child, ~ 10 kg (22 lb) = 50 mg F PTD for 5-6 year old child, ~ 20 kg (44 lb) = 100 mg F PTD for adult, ~ 60 kg (130 lb) = 3000 mg F (3 g) The most popular unit: ppm = part per million (wt/wt ; vol/vol) Water with 1 ppm F = 1 mg/L 9
  11. 11. At higher concentration, usually use %(F-containing products) 1 % = 10,000 ppm 0.1 % = 1,000 ppm 0.05 % = 500 ppmA mounts of dental products required to constitute thePTD for a 5-year-old child100 ml of an adult toothpaste (1000 ppm F)440 ml of a daily F rinse (225 ppm F)110 ml of a weekly F rinse (900 ppm F)8 ml APF gel (12,300 ppm F)4.4 ml F varnish (22,600 ppm F) 10
  12. 12. S igns and symptoms of acute fluoride toxicityNauseaVomitingHypersalivationAbdominal painDiarrhoeaConvulsions (due to fall in plasma calcium)Respiratory failureCardiac failureDeathT reatment of acute fluoride toxicity*Induce vomiting (to remove F)*Give milk or 1% calcium gluconate orally toslow F absorption*Advise hospital of acute F poisoningR EFERENCES 11
  13. 13. 1. K. Jack Toumba, Jinous F. Tahmassebi, RichardBalmer. Paediatric Dentistry in the New Millennium:5. Clinical Prevention: The Role of the General Dental Practitioner2. Zhan X-A, Wang M, Xu Z-R, Li J-X. Toxic effects of F on kidney function and histology in youngpigs. Research report Fluoride 39(1)22–26 January-March 20063.Yiamouyiannis, John, “Water Fluoridation and Tooth Decay: Results from the 1986-1987 NationalSurvey of U.S. Schoolchildren,” Fluoride, Journal of the International Society for Fluoride Research,vol. 23, No. 2; April 1990; p. 55, pp. 28 33.4. Murray JJ. Efficacy of preventive agents for dental caries. Systemic fluorides: water fluoridation.Caries Res 1993; 27(Suppl. 1): 2–8.5. Leverett D, Adair S, Shields C. Relationship between salivary and plaque fluoride levels and dentalcaries experience in fluoridated and non-fluoridated communities. Caries Res 1987; 21: 179 (abstr. 57).6. Fejerskov O, Thylstrup A, Larsen MJ. Rational use of fluorides in cariesprevention.ActaOdontolScand1981; 39: 241–249.7. Martin J. Wagner. Absorption of Fluoride by the Gastric Mucosa in the Rat. J DENT RES 1962 41:6678. Dean HT, Arnold FA, Elvove E. Domestic water and dental caries. Public Health Report (US) 1942;57: 1155–1179.9. Angus C Cameron, Richard P Widmer. Handbook Of Pediatric Dentistry, first edition, 1997, chapter3; Fluoride modalities. Thank You 12