All about topical fluorides, their sources, advantages and disadvantages of each, defluoridation and toxicity of fluorides

2. Topical Fluoride Therapy
 “The delivery of fluorides to the teeth topically in
order to prevent tooth decay”
OR
 “The use of systems containing relatively large
concentrations of fluoride that are applied locally to
erupted tooth surfaces to prevent the formation of
Dental Caries”

4.  At the time of eruption of teeth, the enamel is not yet
completely calcified & undergoes post eruptive
maturation period , approximately 2 years in length,
during which enamel mineralization & maturation
continues.

5.  Through out this period, fluoride as well as other
elements continues to accumulate in the superficial
surface of the enamel ( source– saliva, fluoridated
water & food).
 Most of the fluoride incorporated into developing
enamel occurs during pre eruptive period & post
eruptive period of enamel maturation.
 Highest concentration of fluoride is at the outer layer
of enamel, & the fluoride content decreases as one
progress towards dentine.

6. Mechanism of action of Fluorides
 Increase enamel resistance or Reduction in enamel
solubility
 Increased rate of post eruptive maturation
 Remineralization of incipient lesion
 Interference with plaque microorganisms
 Modification in tooth morphology

7. Mechanism Of Action
 The fluoride ions when substituted into hydroxy apatite
crystal, fit more perfectly into crystal than do hydroxyl
ions.
 This makes the apatite crystals more strong & compact.
 Such crystals are thereby more resistant to acid
dissolution.
 This effect is even more apparent when pH of the enamel
environment decreases & leads to loss of minute quantities
of fluoride from the dissolving enamel.
 This results in simultaneous re-precipitation as fluoridated
hydroxy apatite.

8. Fluoride & Hydroxyapatite crystals
 Fluoride act on the enamel crystal in two ways :
1. Decreasing solubility
2. Improving crystallinity

9. Decreasing solubility
Newly
erupted
tooth
Enamel
structure (
carbonate
apatite –
more soluble
in acid
Matured
tooth
Hydroxyapatite
( less soluble in
acid )
Matured
tooth
with
fluoride
Fluoroapatite (
least soluble in
acid )

10. Improving Crystallinity
 Fluoride ions are able to fill up the occasional voids
and replacing missing hydroxyl ions, thereby can
effectively stabilize the crystal structure by providing
additional and significantly stronger hydrogen bonds

11.  The presence of fluoride reduces, the solubility of
enamel by promoting the precipitation of
hydroxyapatite and phosphate mineral.

12. 2. Increased rate of post eruptive
maturation
 The greatest importance of fluorides to maturation
process lies in its ability to increase the rate of
mineralization of hypo mineralized areas.
 Newly erupted teeth have hypo mineralized areas that
are more prone to dental caries.
 In addition, the entire enamel surface is at its
maximum degree of susceptibility to caries as soon as
it appears in mouth.

13.  Fluoride increases the rate of mineralization, or post
eruptive maturation of these areas.
 Organic material is also deposited into the enamel
surface to further increase its resistance to dental
caries.
 Both mineral ions and organic material are deposited
from saliva.

14. 3. Re mineralization of Incipient
Lesion
 Remineralization , the deposition of minerals into
previously damaged areas of the tooth is a dynamic
process that results 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

15. Fluoride & Remineralization of
teeth

16. 4. Interference with
microorganisms
 Fluoride has been known to inhibit bacterial
enzymatic processes involved in carbohydrate
metabolism. Fluoride interferes with oral bacteria in
two ways :
1. In high concentrations, fluoride is bactericidal. This
is probably how fluoride helps reduces plaque
2. In lower concentrations, fluoride is bacteriostatic. It
helps control the growth of bacteria without
destroying them.

17. 5. Modification in Tooth
Morphology
 There is direct relationship between the amount of
fluoride ingested during tooth development and
incidence of dental caries.
 If fluoride is ingested during tooth development, there
is some evidence to suggest the formation of a more
caries resistant tooth slightly smaller with shallow
fissures.
 The diameters and cusp depths of teeth are smaller if
fluoride is present during tooth development.

18.  Such changes in morphology would tend to decrease
the caries susceptibility of teeth by making them more
self cleansing.

19.  Investigators indicated that primary reaction product
involved is calcium fluoride.
Ca10(PO4)(OH)2 + 20F 10CaF2 + 6 HPO4 + 2OH
 There is a net loss of phosphate ions from treated
enamel. Newer fluoride system incorporates a means
of preventing such loss of phosphate ions.

20.  The Calcium Fluoride which is precipitated when the
solubility product of CaF2 is exceeded could be a
source of fluoride ions to the plaque fluid & into the
porous underlying tooth substance during & after
cariogenic attacks.
 Because it is more soluble than hydroxy apatite or
fluoro apatite & because of its high fluoride content,
CaF2 seems to be an ideal component for the slow
release of fluoride ions at the appropriate times.

21.  The flouride will be released at the tooth surface,
becoming available to inhibit demineralization &
enhance re mineralization.

22. Indications For Topical Fluoride
 Caries active individuals
 Children shortly after periods of tooth eruption,
especially those who are not caries free
 Those who take medications that decrease salivary
flow ( Radiotherapy )
 Mentally or physically challenged individuals.

23. Classification
 Operator administered
- Fluoride solutions
sodium fluoride 2%
stannous fluoride 8%
- Fluoride gels
acidulated phosphate
fluoride 1.23%
-Fluoride varnishes
duraphat
fluorprotector
 Self administered
-Fluoride dentifrices
- Sodium fluoride
- Fluoride mouth rinses
- dentifrices containing
monofluorophosphate

24. Rationale For Using Topical fluoride
agents
 To speed the rate and increase the fluoride acquisition
above the level, which occurs naturally.
 Since immature and porous enamel acquires fluoride
rapidly and since the enamel surface of newly erupted
tooth undergoes rapid maturation, it follows that the
best time to apply topical fluoride is soon after
eruption.

25. Sodium Fluoride 2%
 Is prepared by dissolving 20 g of NaF powder in 1 litre of
distilled water in a plastic bottle ( or 2g of NaF powder
in 100ml of distilled water)
 If stored for long time in the glass containers, it can
react with silica of glass ion to form SiF2 thus reducing
the availability

26. Application ( Knutson Technique )
 Cleaning and polishing of teeth
 Isolation done with cotton rolls
 Teeth are dried
 NaF2 is applied with cotton applicators for upto 4 min
 Procedure is repeated for every quadrant
 After completion patient is instructed to avoid eating,
drinking and rinsing for 30 min
 This is to prolong the availability of ‘F’ ions to react with
tooth surface
 2nd ,3rd and 4th applications are done at weekly intervals

28. Recommended Ages
 Full series of 4 treatments is recommended at ages of
3, 7, 11 and 13
 As this coincides with the eruption of different groups
of primary & permanent teeth

29. Cont’d
 When in sufficient amount the CaF2 reacts with the
hydroxyapatite to form fluoridated hydroxyapatite
which increases the surface concentration of Fluoride
thus making the tooth surface:
- more stable
- less susceptible to dissolution by acids
- interferes with the plaque metabolism
- helps in the remineralization of initial
decalcified areas

30. Disadvantages
 The patient must take 4 visits to the dentist within a
relatively short time intervals.
 The caries reduction is not satisfactory 20-25 %.

31. Stannous Fluorides- 8%
 Preparation ( Muhlers Solution)
 Must be prepared freshly each time because it has no
shelf life
 0.8 g of stannous fluoride is dissolved in 10ml of
distilled water in a plastic container and shaken briefly
 Immediately applied to the teeth

32. Method of Application
 Tooth surface must be cleaned and polished
 Teeth are isolated and dried with air
 Freshly prepared 8% solution is applied to the teeth
with cotton applicators
 Applied for 4 min.

33. Recommended Frequency
 Once per year

34. Mechanism of Action
 When stannous fluoride reacts with the hydroxy
apatite following products are achieved :
- tin reacts with the hydroxyapatite to form
Stannous Tri- fluorophosphate which is more
resistant to decay
- tin hydroxyapatite
- calcium trifluorophosphate
- calcium fluoride

35. Cont……
 Required only once per year
 Must be prepared fresh each time
 Metallic taste

36. Acidulated Phosphate Fluoride
(1.23%)
 Prepared by dissolving 20 g of NaF in 1 litre of 0.1M
phosphoric acid
 To this Hydrofluoric acid 50 % is added to adjust pH at
3 and fluoride concentration at 1.23 %

37. Application
 Teeth are isolated and dried
 APF solution is continuously and repeatedly applied
with cotton applicators
 Kept moist for 4 min

38. Recommended Frequency
 Applied twice per year

39. Mechanism of Action
 When applied , it initially leads to dehydration and
shrinkage of hydroxyapatite crystals
 With further hydrolysis an intermediate product is
formed called Dicalcium Phosphate Dihydrate
(DCPD)
 This DCPD is highly reactive with “F” & leads to
formation of fluoroapatite “F”.

40. Properties
 No staining of structure
 Should be kept in polyethylene bottle
 Sour and bitter in taste
 Repeated applications are essential

41. Advantages
 Semiannual or annual application.
 Chemically stable & can be stored for ready to use.
 Does not produce staining of the enamel.
 They are available in different flavouring tastes.
 Expected caries reduction is 30-40 % better than NaF
& SnF2.

43. Fluoride Varnish
 Duraphat( NaF varnish)
 Fluoroprotector (silane fluoride)

44. Varnish
 Varnish is a transparent, hard, protective finish or film
primarily used in wood finishing but also for other
materials

45.  Rationale :
1. After topical fluoride application, there is substantial
leaching of absorbed fluoride from the surface enamel.
To prevent this immediate loss, fluoride has been
incorporated in varnishes that have ability to adhere to
enamel for long period & it is hypothesized that it will
slowly release fluoride to the teeth.
2. The retentive & possible slow release of fluoride
increase the exposure time of the fluorides by several
days without increasing chair side time & presumably
allow fluoride to be more permanently bound to teeth.

46. Composition
 Fluoroprotector:
- colourless
- Fluoride is in the form of Difluorosilane ethyl
difluorohydroxy silane
- active fluoride is available as 700ppm
 Duraphat:
-NaF varnish containing 22.6 mg F/ml suspended
in an alcoholic solution of the natural organic
varnishes
- active F is 22,600 ppm

47. Method of Application
 Isolate and dry the teeth
 Apply the varnish 1st on the lower arch and then on the
upper arch
 Apply with the single tufted brush
 Applied for 4 min
 Instruct the pt not to eat, drink or rinse for 1 hour, not
to eat solids but take liquids and semi solids only till
next morning
 Contact should be maintained for 18 hours for
prolonged interaction between fluoride and enamel

48. Mechanism of Action
 When applied, a reservoir of Fluoride ions gets build
up around the enamel of teeth
 Slow and continuous release of fluorides s deeper
penetration of the fluoride and formation of the
fluoroapatite

49. Recommended Dosage
 0.5 ml of duraphat for single application contains
11.3mg F
 0.5 ml of fluorprotector contains 3.1mg F

50. Fluoride Dentifrices
 Commonly used are :
Sodium mono fluorophosphates , NaF and SnF2
 Mono fluorophosphate dentifrices are more advantageous
than NaF and SnF2 because:
- neutral pH
- Greater stability to oxidation and hydrolysis
- more Shelf life
- More availability of Fluorides
- No staining of teeth

51. Indications
 Caries prevention
 In caries risk patients
 desensitization

52. Mechanism of Action
 Monofluorophosphate is deposited in the crystalline
lattice and in subsequent intracrystalline transposition
( Erricsson 1963)
 Anticariogenic activity is due to the
monofluorophosphates as such and it may exchange
with the phosphate groups in the apatite crystals

53. Preparations
 As gels & pastes

54. Procedures
 Select a fluoride containing dentifrice
 Place it on tooth brush
 Spread it over the teeth
 Proceed with the correct method for sulcular removal
of plaque

55. Fluoride Content
 Dentifrices contain usually around 800 to 1000 ppm,
while the available amount is 500 to 600 ppm

56. Recommendations for Usage
 Below 4 years: not recommended
 4-6 years: once a day
 6-10 years: twice with fluoridated paste once with
normal paste
 Above 10 years: brush 3 times with fluoridated paste

57. Fluoride Mouth Rinses
 Self application method
 Should not be used under children of 6 years age, with
orofacial defects

58. Preparation( house preparation)
 By dissolving 200 mg NaF tablet in 5 teaspoons of
fresh clear water (25 ml)
 Sufficient for daily mouth rinse of a family of 4
members

59. Method of Use
 Rinse daily with one teaspoon after brushing before
bed
 Swish between teeth with lips tightly closed for 60 sec

60. Benefits
 30 to 40 % reduction in the caries incidence is
reported

62. Controlled Released Fluoride
 Intra oral device for sustained release of fluoride
 Device consists of a central depot of NaF mixed with
plastic copolymer and surrounding by a rate
controlling membrane
 Device can release fluoride at a rate of from 0.02 to
1mg/day

64. Definition
 “Symptoms manifested as a result of over dosage of the
excessive administration of the fluorides”

65. Concentration and Effect
Concentration Medium Effect
1ppm water Caries reduction
2ppm Air Injury to vegetation
More than 2 water Mottled enamel
8 ppm Water 10% osteosclerosis
50 ppm Food/water Thyroid changes
100 ppm Food/water Growth retardation
< 125ppm Food/water Kidney changes
2.5-5 gm Acute dose death

66. Acute Fluoride Toxicity
 Due to single ingestion of large amount of fluorides
 Dose is about 5 gram
 The probable range is 2-10 grams
 Very rare occurring
 Usually reported in the suicide attempts

67. Certainly Lethal Dose (CLD)
 Amount of drug likely to cause death
 Adult………….34-64 mg F/kg

68. Safely Tolerated Dose (STD)
 STD = ¼ CLD

69. Symptoms of Acute Toxicity
 Vomiting , nausea , diarrhea
 Pain in abdomen and extremities
 Difficulty in speech
 Thirst
 Weak pulse
 Coma
 Convulsions
 Cardiac arrhythmias Death
 Death occurs within 4 hours

70. Pathological Changes
 Corrosive changes in GIT leading to hemorrhage

71. Treatment
 Large amount of Milk
 Lime water
 Al(OH)3
 Vomiting
 While in hospital…………
cardiac monitoring
gastric lavage
oral IV calcium gluconate
urinary output to be maintained

72. Chronic Fluoride Toxicity
 “ Due to long term ingestion of small amount of
Fluorides”
 Characterized by the minute white flecks, yellow or
brown spot areas, scattered irregularly over the tooth
surface
 Premolar is the most effected tooth
 Occurs symmetrically in the dental arches

73. Treatment of Mottled teeth
 Milder forms diminish with time
 Polishing
 Bleaching with H2O2
 Composite use
 Use of veneers

74. Radiographic Features
 Stage 1:
Spinal column and pelvis show the roughening and
blurring trabeculae
 Stage 2 :
Trabeculae merge together and bone has diffuse
structure less appearance
 Stage 3 :
Bone appear as marble white shadow

77. Definition
 “Methods of water treatment that reduce the
concentration of fluoride in the water, normally, in
order to make it safe for human consumption”

78. Methods
 Ideal method is to blend the excessively fluoridated
water with another water supply deficient in fluoride
 Only expenditure is the connecting of the pipes

79. Additive Methods
 Chemicals are added to precipitate the fluoride and
then the fluoride is passed through mixing basins,
flocculation units, setting basins and filtering beds
 The chemicals used are
- lime
- magnesium compounds
- aluminium sulfate

80. Adsorption Method
 Water is run over the contact beds, where fluoride is
removed by the ion exchange
 Chemicals used are:
synthetic hydroxyapatite
Ion exchange resin
Activated alumina
Polystyrene
Defluoron
Magnesia