Mechanisam of action of Fluorides

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Maitrey    on Jul 19, 2012 Says :

Thanks khusbu
Khushbu    on Jul 19, 2012 Says :

great presentaion. well presented slides.
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Slide 1 : Mechanism of action of Fluorides BY: Dr Maitrey G Bhalodia
Slide 2 : Contents: Introduction. Theories of Mechanism of action of fluorides. Schematic illustration fluoride action. Methods of Fluoride Applications. References
Slide 3 : Introduction Dental Caries:It is an infectious, microbiological disease of teeth that results in localized dissolution and destruction of the calcified tissue. It is one of the most common chronic disease of the modern time. Dental caries is an multifactorial in etiology with bacteria, susceptible tooth surface, and diet playing a major role. It has a wide range of the clinical feature affecting all age of the group and all surface of the teeth.
Slide 4 : The last few decades have witnessed a major decline in the prevalence of caries in the developed countries. This is due to widespread use of fluorides and other preventive measures. The present trend in treating the dental caries is directed more towards prevention and minimal intervention rather than the traditional “ DRILL AND FILL” dentistry
Slide 5 : Caries continues to be a major problem Need an improved approach to prevention & therapy Major contributor to reductions in decay during the last 20 years by the universal use of fluoride (F) products.(Featherstone JD, 1999)
Slide 6 : The use of fluorides for dental purposes began in the nineteenth century(1892) Sir James Crichton Browne emphasized the importance of fluoride Florine is the most electronegative element and therefore highly reactive. It does not occur in the elemental state (F2) in nature but is widespread in nature, occurring in fresh water, vegetables, blood, milk and organic compounds.
Slide 7 : Increased enamel resistance or Reduction in enamel solubility Remineralization of incipient lesions Increased rate of post eruptive maturation Interference with plaque microorganisms Modification in tooth morphology Since fluoride can affect both the inorganic tooth structure & the bacterial metabolism in plaque, several mechanism of action have been proposed. Theories of Mechanism of action Of fluorides
Slide 8 : Increased enamel resistance or Reduction in enamel solubility Enamel structure
Slide 9 : It has been well established that dental caries involves dissolution of enamel by acids from bacterial plaque and that dissolution is inhibited by the presence of fluoride. Fluorides acts by 2 ways: Decreasing solubility Improving Crystallinity
Slide 10 : Because fluoride form fluorapatite, which is less soluble mineral ,it has been thought that anticaries effect of fluoride is the result of reduced solubility. When enamel is exposed to a pH about 5.5 or lower, it will dissolve. Ca10(PO4)6(OH)2+8H=10Ca + 6HPO4+2H2O Calcium and fluoride ions released from the apatite during initial dissolution forms Calcium Fluoride (CaF2) on the surface of the fluorapatite hence reducing it solubility. Decreasing solubility:
Slide 11 : When the hydroxyapatite is exposed to low fluoride concentration a layer of fluorapatite forms on the hydroxyapatite crystals. The thin layer governs the rate of dissolution. VOID theory: hydroxyapatite crystals in dental enamel are small and contain several impurities.prescence of fluoride ion in law concentration also effectively increase the Crystallinity of the hydroxyapatite. This is based on void theory Improving Crystallinity:
Slide 12 : It concerns with association of the hydroxyl ion with the calcium ion in the unit cell, fluoride ions are able to fill up this voids and replacing the missing hydroxyl ions, Thereby can effectively stabilize the crystal structure by providing additional and significantly stronger hydrogen bonds.
Slide 13 : Remineralization of incipient lesions Fluorides and Remineralisation Remineralisation Demineralization Fluorides
Slide :
Slide 15 : Remineralization, the deposition of the minerals into previously damaged areas of the tooth is a dynamic process that result in reduced enamel solubility. This increase in enamel resistance is achieved through the growth of the crystals which become larger than those in either demineralized or sound enamel .this larger crystals are more resistance to acid attack. The most effective remineralizing solution contain fluorides in combination with calcium and phosphate ions.
Slide 16 : Fluorides enhance the remineralization process by accelerating the growth of the enamel crystals that have demineralization. Hydroxyapatite crystals and Fluorides: When it exposed to low concentration of fluoride, will form fluorapatite crystals. When it exposed to High concentration of fluoride, there is a formation of calcium fluorides. That calcium fluoride further breakdown into the calcium and fluoride.
Slide 17 : That fluoride is highly reactive and acts commandos. They come back to the teeth and reacts with the hydroxyapatite crystals and lead to the formation of the fluoridated hydroxyapatite(FHA) .later FHA on exposure of fluoride on longer period of time leads to formation of fluorapatite. Thus calcium fluoride act as a reservoir
Slide 18 : Increased rate of post eruptive maturation Fluorides has ability to increase the rate of mineralization of hypomineralized area. Newly erupted teeth often have hypomineralizesd area that are prone to dental caries. and entire enamel surface is at maximum degree of susceptibility to caries as soon as it appears in the mouth, fluorides increase the rate of mineralization of this area. Organic material is also deposited into the enamel surface to further increase to its resistance to dental caries and it is deposited from the saliva.
Slide 19 : Interference with plaque microorganisms Fluoride interferes with oral bacteria in two ways In high concentrations, fluoride is bactericidal. it affect the growth and metabolism, It inhibit bacterial enzymatic process involved in carbohydrate metabolism. It acts on enolase enzyme thus prevents the conversion of glucose to lactic acids.
Slide 20 : In lower concentrations its bacteriostatic. It inhibit the acid formation. It helps the control the growth of the bacteria without destroying them. Fluoride lodge in plaque and inhibit the bacterial enzymes responsible for acid metabolism. Plaque fluid contain fluoride. decreased pH--fluoride level increased.
Slide 21 : Modification in tooth morphology Fluoride administered during tooth formation may result in shallower and wider fissures, More rounded cusps thus reducing the number and size of sites where food and plaque could accumulate. Fluoride affects the morphology of the teeth making them more self-cleansing
Slide 22 : Schematic illustration fluoride action
Slide 23 : Methods of Fluoride Applications Topical Systemic Professionally applied: -Community water fluoridation -Sodium fluoride-2% solution -Salt Fluoridation -stannous fluoride-8% solution -School water fluoridation -Acidulated phosphate gel(APF gel)-1.23% -Milk Fluoridation -Fluoride varnish -Fluoride Supplements -DURAPHAT-22600 ppm -FLUOR PROTECTOR-7000 ppm -Fluoride Paste(1000 ppm) Self applied: -Fluoride dentifrices(1000 ppm) -Fluoride Mouthwashes 0.2%Naf -900 ppm for weekly use 0.05%Naf-225 ppm for daily use
Slide 24 : References: Essential of preventive and community dentistry-Sober Peter. Textbook of preventive and community dentistry- Hiremath Internet(www.ncbi.nlm.nih.gov), (www.fluoridealert.org )
Slide 25 : Thank you BY:Dr Maitrey g Bhalodia

 


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Add as Friend sweetu_maitrey     10 Months ago.
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this seminar is about MOA of Fluorides in dentisry..comment it and rate it
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