MECHANISM OF ACTION OF FLUORIDE

PEDAGOGY SLIDES

1. MECHANISM OF ACTION OF FLUORIDES SHABNA.G.S FIRST YEAR MDS DEPARTMENT OF PUBLIC HEALTH DENTISTRY GOVERNMENT DENTAL COLLEGE,KOTTAYAM 1

2. LESSON PLAN NAME OF THE PRESENTER : SHABNA.G.S SUBJECT : PUBLIC HEALTH DENTISTRY TOPIC : MECHANISM OF ACTION OF FLUORIDES DATE : 27-02-2019 DURATION :1 HOUR TARGET AUDIENCE : III YEAR B.D.S. STUDENTS 2

3. TEACHING LEARNING METHOD: LECTURE TEACHING LEARNING MEDIA: AUDIOVISUAL AID, LCD PROJECTOR, WHITE BOARD 3

4. EVALUATION DURING THE CLASS : OBSERVATION OF STUDENTS RESPONSE TO QUESTIONS AT THE END OF THE CLASS : THROUGH ASKING QUESTIONS 4

5. MECHANISM OF ACTION OF FLUORIDES 5 GENERAL OBJECTIVE

6. BASIC INFORMATION ON ELEMENT FLUORINE BASIC INFORMATION ON STRUCTURE OF HYDROXYAPATITE ‘POOLS’ OF FLUORIDE IN THE ORAL ENVIRONMENT 6 SPECIFIC OBJECTIVE

7. PROPOSED MECHANISMS Increase enamel resistance/ Reduction enamel solubility Increased rate of post eruptive maturation Remineralisation of incipient lesions Interference with plaque microorganisms Modification in tooth morphology 7 SPECIFIC OBJECTIVE

8. FLUORINE 8

9. FLUORINE 9

10. FLUORINE ATOMIC NO. 9 ATOMIC WT. 19 HALOGEN FAMILY MOST ELECTRONEGATIVE ELEMENT 10

11. CHEMICAL STRUCTURE OF ENAMEL 11

12. CHEMICAL STRUCTURE OF ENAMEL 12

13. UNIT CELL OF HYDROXYAPATITE 13 PHOSPHATE CALCIUM HYDROXYL ION Ca10 (PO4)6 (OH)2

14. 14 CARBONATES MAGNESIUM FLUORIDE UNIT CELL OF HYDROXYAPATITE

15. CARIES RELATED EXTRANEOUS IONS 15

16. CORE OF THE CRYSTALS 16 DISRUPTIVE FOR CRYSTAL STRUCTURE LESS STABLE MORE SOLUBLE IN ACIDS MAGNESIUM AND CARBONATES

17. 17 HYDROXYAPATITE CRYSTAL SHOWING REPLACEMENT OF ONE HYDROXYL BY A FLUORIDE ION FLUORIDE HYDROXYL COLUMN

18. Newly erupted tooth Matured tooth Matured tooth With fluoride 18 Enamel structure (carbonated apatite- more soluble in acid) Hydroxyapatite (less soluble in acid) Fluorapatite (least soluble in acid) Fluoride uptake FIRMLY BOUND DIFFERENT LEVELS OF ENAMEL SOLUBILITY IN ACIDS

19. LOW CONCENTRATION OF FLUORIDE 19 Hydroxyapatite Low concentration of Fluoride [Systemic fluorides] Fluorhydroxyapatite Fluoride Fluorapatite + Ca 10 (PO 4 ) 6 (OH) 2 + 2F - Ca 10 (PO 4 ) 6 F 2 + 2OH – (HYDROXYAPATITE) (FLUOROAPATITE) +

20. Hydroxyapatite + high conc. of fluoride [Topical fluorides] CaF 2 + Po 4 + Hydroxyapatite HIGH CONCENTRATION OF FLUORIDE Hydroxyapatite + CaF 2 Fluoridated hydroxyapatite ( FHA) Fluorapatite Repeated exposure to fluoride over long period of time CaF 2 Ca ++ and F F - + LOOSELY BOUND FLUORIDE 20

21. Ca 10 (PO 4 ) 6 (OH) 2 + 20F - 10CaF 2 + 4PO 4 3- + 2OH – (Hydroxyapatite ) (calcium fluoride) 21

22. CRITICAL PH The critical pH is the pH at which saliva and plaque fluid cease to be saturated with calcium and phosphate, thereby permitting the hydroxyapatite in dental enamel to dissolve Critical pH for Hydroxyapatite is around 5.5 Fluorhydroxyapatite is around 4.5 22

23. DENTAL MINERAL DYNAMICS Enamel exposed to a pH 5.5 or lower, it will dissolve Ca10(PO4)2(OH)2 + 8H+ 10 Ca++ + 6HPO- + 2H2O 23 The Stephan Curve

24. DENTAL MINERAL DYNAMICS concentration of calcium, phosphate and other ions in the solution Plaque stops producing acid pH rises and precipitation of mineral cyclic phenomenon 24

25. ‘POOLS’ OF FLUORIDE IN THE ORAL ENVIRONMENT 25

26. MECHANISM OF ACTION 26 Increase enamel resistance/ Reduction enamel solubility Increased rate of post eruptive maturation Remineralisation of incipient lesions Interference with plaque microorganisms Modification in tooth morphology

27. INCREASE ENAMEL RESISTANCE/ REDUCTION ENAMEL SOLUBILITY 27 FLUORIDE IN PLAQUE FLUID AC I D I C ENV I RONMENT PENETRATE AT THE SUBSURFACE ADSORB TO THE CRYSTAL SURFACE PROTECTS CRYSTALS FROM DISSOLUTION ACIDS

28. 28 INCREASE ENAMEL RESISTANCE/ REDUCTION ENAMEL SOLUBILITY

29. INCREASED RATE OF POST- ERUPTIVE MATURATION Hypo mineralized areas ( very common in newly erupted teeth: prone to dental caries) Fluoride RATE OF MINERALIZATION Post-eruptive maturation and remineralisation are similar process but maturation occurs in hypo mineralized areas while remineralisation occurs in demineralised areas ( incipient caries) 29

30. REMINERALIZATION OF INCIPIENT LESIONS 30

31. INTERFERENCE WITH PLAQUE MICROORGANISMS 31 FLUORIDE HIGH CONCENTRATION LOW CONCENTRATION BACTERICIDAL BACTERIOSTATIC

32. INTERFERENCE WITH PLAQUE MICROORGANISMS 32

33. INTERFERENCE WITH PLAQUE MICROORGANISMS 33 FLUORIDE INHIBITS

34. MODIFICATION IN TOOTH MORPHOLOGY 34 FLUORIDE INGESTED DURING TOOTH DEVELOPMENT SHALLOW FISSURES DECREASED DIAMETER SMALLER CUSP TIPS

35. SUMMARY 35 The use of fluoride in dentistry the most successful preventive health measures in the history of dental care Enamel exposed to fluoride exhibited Denser crystal Greater total mineral density Higher degree of crystallinity More fluoride and less carbonate contents

36. Proposed mechanisms are- 36 Increase enamel resistance/ Reduction enamel solubility Increased rate of post eruptive maturation Remineralisation of incipient lesions Interference with plaque microorganisms Modification in tooth morphology

37. 37 Understanding the mode of action of fluoride has an essential role in the further development of products and programmes for caries prevention

38. QUESTIONS 38 ATOMIC NUMBER OF FLUORINE----------------------------------- CHEMICAL FORMULA FOR HYDROXYAPATITE-------------------------------------- TYPE OF BOND BETWEEN FLOURIDE AND HYDROXYL ION------------------------------ EXTRANEOUS IONS THAT FACILITATE DEMINERALISATION-------------------------- CRITICAL PH FOR HYDROXYAPATITE AND FLUORHYDROXYAPATITE ARE---------- EXPOSURE OF HYDROXYAPATITE TO HIGH CONCENTRATION OF FLUORIDE PRODUCE-------- NAME DIFFERENT MECHANISM OF ACTION OF FLUORIDE---------------------------

39. BIBLIOGRAPHY Buzalaf , M.A.R. ( ed ) (2011): Fluoride and the Oral Environment. In: Monograph in Oral Science 22. Basel: Karger Fejerskov O, Kidd EA, Nyvad B, Baelum V: Defining the disease: an introduction. Fejerskov O, Kidd E: Dental Caries The Disease and its Clinical Management 2Oxford, Blackwell Munksgaard , 2008 Robinson C (2009). Fluoride and the caries lesion: Interactions and mechanism of action European Archives of Paediatric Dentistry 10(3) 136-140 39

40. BIBLIOGRAPHY Peter S. 2nd ed. NewDelhi : Arya ( Medi ) Publishing House; 2004. Essentials of Preventive an Community Dentistry Rošin-Grget K, Peroš K, Sutej I: The cariostatic mechanisms of fluoride. Acta Med Acad 2013;42:179-188 Rosin- Grget K, Lincir I: Current concept on the anticaries fluoride mechanism of action. Coll Anthropol 25:703–712, 2001 . 40

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