Topical Fluorides

1. Topical Fluorides

2. Definition Topical fluorides describe those delivery systems which provide fluoride for a local chemical reaction to exposed surfaces of the erupted dentition Professionally applied- 5000-19000 ppm Self applied- 200- 1000 ppm

3. Indications High caries risk past caries experience, incidence, number of initial smooth surface lesions, dietary, microbiological, salivary and tooth factors, age. Assessment of knowledge, attitude and practice of the oral hygiene.

4. Rationale for using topical fluorides Speed the rate and increase the concentration of fluoride above the level which occurs naturally. Best to apply fluoride soon after the eruption of the tooth Apply on an incipient lesion.

5. Fluoride vehicles Aqueous solutions and gels Thixotropic solution Fluoridated prophylactic paste Foam

6. Aqueous solutions and gels Principal vehicle Both are equally effective Solution application is time consuming and expensive Gel is an aqueous suspension of organic or inorganic molecules that are arranged in a weak three dimensional network producing a thickening or gelling of the entire network. Agent used is hydroxyethyl cellulose

7. Advantages of the gel Adheres to teeth for considerable time. Possible to treat three or four quadrants at the same time Less chances of accidentally ingesting a large dose Eliminates the need for continuous wetting

8. Thixotropic solutions They are not gels but are viscous solutions High viscosity under storage but become fluid under high stress and shearing force. More stable at lower ph and do not run off the tray as conventional gels.

9. Fluoridated prophylactic paste Cleaning and fluoride application in one step Sodium fluoride or stannous fluoride used First marketed paste contained stannous fluoride as agent and zirconium silicate as the abrasive. Prophylaxis alone removes fluoride rich layer on the surface which is compensated by the use of fluoridated prophylactic paste

10. Foam Minimize the risk of overdosage Maintain the efficacy of topical fluoride treatment Much lighter than gel and hence only small amount needed for topical application (4 g for gel; 1g for foam) Surfactant has cleansing action lowering surface tension and facilitate penetration in interproximal surfaces where need is most For young and disabled children as suctioning is not required.

11. Method of application Paint on technique Tray technique Paint on technique Rinse- isolation- saliva absorbers, saliva ejectors, dried- aqueous solution applied for 4 minutes, floss soaked with fluoride passed interproximally. Tray technique Wax or paper trays with foam inserts

12. Fluoride varnish Increases the contact time with the tooth Reduces the chances of leaching away of fluoride representing unreacted fluoride ion and calcium fluoride. Schmidt 1964, developed method in which teeth coated with lacquer containing fluoride Duraphat (NaF with 2.26% F in organic lacquer) Fluorprotector (silane fluoride with 0.7%F)

13. Composition Fluorprotector- colorless polyurethane lacquer . fluoride compound is difluorosilane (3 methoxy-4 hydroxy-cyclohexyl)-ethyl-difluorohydroxy silane. Fluoride content is 7000 ppm. Duraphat is sodium fluoride in varnish form containing 22.6 mg F/ ml or 22, 600 ppm of active fluoride suspended in an alcoholic solution of natural organic varnishes.

14. Mechanism of action Applied in neutral ph. Reservoir gets build up around the enamel of teeth. 10Ca5 (PO4)3OH+ 10 F- = 6Ca5(PO4)3F + 2CaF2 + 6 Ca3(PO4)2 = 10OH- 2Ca5 (PO4)3OH + CaF2 = 2Ca5 (PO4)3F + Ca(OH)2

15. Fluorprotector R-SiF2OH + H2O = R-Si (OH)3 + 2HF Fluorprotector , high viscosity varnish penetrates the porosities of enamel forming tags 0.5 – 1.0 um long which act as a fluoride reservoir accounting for more F deposition in enamel On the other hand these tags further block the pathways for F and do not let the remineralization of initial lesions occur explaining the less caries inhibition

16. Technique Teeth dried, isolated (not with cotton rolls as varnish stick to cotton). 0.3 to 0.5 ml of varnish equivalent to 6.9- 11.5 mg is used to cover full dentition. First on lower arch and then on upper arch Applied for four minutes Not to rinse or drink anything for one hour and not eat anything solid till next morning.

17. Safety of varnish Plasma fluoride level was found to be 270 ng/ml after 0.5 ml of application of Duraphat much les than the nephrotoxic threshold level of 850 ng/ml in plasma.

18. Techniques Knutson’s technique (four weekly interval application at 3, 7 ,11, 13 years) Szwejda Knutson technique (multiple chairs used) Muhler’s technique (teeth kept moist for 4 minutes; done every six months) Mercer and Muhler technique (teeth kept moist for 30 seconds) Dubbing and Muhler technique (4 minutes application preceded by prophylaxis with stannous fluoride and passing unwaxed floss interproximally) Englander technique ( 3 minutes application 3 times a week using special mouthpieces made of thermoplastic vinyl resin)

19. Neutral Sodium Fluoride First topically applied fluoride 40% reduction in caries by four topical applications at weekly intervals Method of preparation Dissolve 20 g of NaF in 1000 ml of distilled water in plastic bottle. 2% NaF Contains 9040 ppm of fluoride

20. Method of application Cleaning, isolation, teeth dried, applied with cotton applicator tips, allowed to dried for 3- 4 min Applied at weekly intervals but not preceded by prophylaxis Recommended ages 3, 7 ,11, 13 years

21. Advantages Relatively stable Taste well accepted Non irritating to gingiva and does not cause discoloration No need for annual or semi annual applications Disadvantages Four visits are required

22. Mechanism of action Ca10(PO4)3 (OH)2+ 20 F- = 10CaF2 + 6 PO + 2OH- 2Ca5 (PO4)3OH + CaF2 = 2Ca5 (PO4)3F + Ca(OH)2 “choking off” of reaction

23. Stannous Fluoride (Muhler’s solution) Second topical fluoride agent to gain importance More effective than sodium fluoride 8%solution used for children and 10% for adults Method of preparation freshly prepared as it is not stable and soon after mixinig become cloudy due to the formation of tin hydroxide

24. Technique of application Tooth surface cleaned , unwaxed floss passed through interproximal area, painted on tooth surface with continuous application every 15- 30 seconds for four minutes. Applied once per year

25. Advantages Frequency of application conforms to the practicing dentists usual patient recall system. Disadvantages Not stable Disagreeable in taste Reversible tissue irritation manifested by gingival bleaching. Pigmentation of teeth (light brown color).

26. Mechanism of action At low concentration Ca5(PO4)3 (OH)2+ 2SnF2 = 2CaF2 + 2Sn2(OH)PO4 + Ca3 (PO4)2 at high concentration Ca5 (PO4)3OH + 16SnF2 = 2CaF2 + 2Sn3F3PO4 + Sn2 (OH)PO4 + 4CaF2(SnF3)2

27. Acidulated phosphate fluorideBrudevold’s Solution 1.23% fluoride as sodium fluoride buffered to a pH of 3-4 in a 0.1 M phosphoric acid. Dissolving 20 g of sodium fluoride in 1 litre of 0.1 M phosphoric acid and 50% hydrofluoric acid is added to adjust the pH at 3.0 and fluoride ion concentration at 1.23%. Gelling agent methylcellulose or hydroxyethyl cellulose is added to adjust the pH at 4-5.

28. Technique of application Tray technique for gel and paint on technique for solution 6 or 12 months intervals Reapplied every 15- 30 seconds. total application time is 4 minutes. Not to eat drink or rinse mouth for 30 minutes.

29. Mechanism of action Initial application leads to dehydration and shrinkage in the volume of hydroxyapatite crystals which further on hydrolysis forms an intermediate product called dicalcium phosphate dihydrate (DCPD). DCPD is highly reactive and forms immediately.

30. The amount and depth of fluoride deposited is dependent on amount and depth at which DCPD is formed. Because of this APF is applied at every 30 seconds and tooth is kept wet for 4 minutes. Ca5(PO4)3 (OH)2+ 4H+ = 2Ca++ + 3HPO4- + H20- + 0H- Ca++ + HPO4- = Ca.HPO4.2H2O 5Ca.HPO4.2H2O = Ca (PO4)3F + 2HPO4-

31. Advantages Requires only 2 applications in a year and is thus suited for most dental offices routine. Can be self applied and thus cost of application gets reduced. Able to deposit fluoride at a deeper depth than neutral sodium fluoride or stannous fluoride. Need not be freshly prepared.

32. Disadvantages Repeated application for four minutes is done so necessitates the use of suction It is acidic, sour and bitter in taste. It cannot be stored in glass bottles. Repeated application or exposure to porcelain and composite can result in loss of materials, surface roughening and possible cosmetic changes.

35. Amine fluoride Found by Muhlemann (1957) that certain organic fluorides were superior to inorganic fluoride due to combination of chemical protection by fluoride and physicochemical protection by organic part. Contain a mixture of two long chain alipahtic amine hydrofluorides at pH 4.5

36. Advantages Reduce enamel solubility Act as surface agents Antibacterial properties Reduced plaque formation and antiglycolytic activity Reduction of enamel solubility better than SnF2 or APF.

37. Calcium fluoride is formed although the calcium fluoride precipitate is different from those formed by sodium fluoride because of adsorption of amine moiety. Mechanism of action

38. Enhancing fluoride fixation in enamel Increase in frequency of application and time exposure Pretreatment of enamel surfaces (0.05 M phosphoric acid) By acidified saturated solution of dicalcium phosphate dihydrate Use of complexing agents (iron, tin titanium, beryllium)

39. Recommendations for topical application of high potency fluoride products No more than 2g of gel per tray or 40%of tray capacity should be dispensed. Saliva ejector should be used Expectorate for 30 seconds to 1 minute after 4 minutes application. 5- 10 drops of product per tray should be used in custom individually fitted trays.

40. Recommendations for use of topical fluorides Caries active individuals Children shortly after periods of tooth eruption On medication that decrease salivary flow Receiving radiation of head and neck After periodontal surgery when roots of neck have been exposed Patients with fixed or removable prosthesis After placement or replacement of restorations Eating disorder or undergoing a change in lifestyle Mentally or physically challenged individual