1. Dental Structure and Fluoridation
Dr. Iyad ABOU RABII
DDS. OMFS. MRes. PhD

2. Dental Structure

3. Dental structure
(Enamel)
 The enamel is the most highly mineralized tissue in the
body consisting of
 95% hydroxyapatite (HAP)
 4.5% water
 0.5% organic matrix.

4. Dental structure
(Enamel)
 Enamel is the visibl white part of the crown.
 It contains calcium phosphate, fluorine, protein
and water.
 Thanks to this combination, the enamel optimally
protects the interior of each tooth from
temperature differences, bacteria and acids, as
well as from the pressure required to chew food.

5. Mineralization
• It is the change of physical stat of a substance
from liquid and semi-liquid status to solid
status through deposition of minerals
(calcium and phosphate) .

6. Mineralization

7. Mineralization
Localization of
mineral within
the collagen
fibril.

8. Hydroxy Apatite (HA)
and fibrillo-
carbonato-apatite

9. Hydroxyapatite Crystals
Samson
 Chemical formula is Ca10 (Po4). X2
 Hydroxyapatite Crystal has one longitudinal axis C and three
transversal axis a1, a2, a3
 the two axis a1,a2 are perpendicular with the axis C with an
angle of 120 between theses two axiss

10. Enamel rod Structure

11. Enamel rod Structure
Enamel.
A, Its rod structure as seen in ground sections with the
light microscope.
B, Electron micrography shows that enamel consists of a
mass of crystallites organized into rod and interrod
enamel.

12. Fluoridation

13. Contents
A. Goals of fluoride administration
B. Non-professional fluoride administration
1. Systemic
2. Topical gels
3. Rinses
4. Dentifrice
C. Professional administration
1. Topical
2. Varnish

14. GOALS OF FLUORIDE (F) ADMINISTRATION
1. Do no harm 3. Arrest active decay
F
Fluorosis or
toxicity
2. Prevent decay on in tact dental
surfaces 4. Remineralize decalcified teeth
F
F

15. TEXT
Do not harm the patient
1. Probable toxic dose (PTD):
• PTD is 5 mg F/kg body weight.
For a 20 kg 5 to 6 year old this would be 100 mg
for a 10 kg 2 year old, 50 mg.
F content of dental products or treatments may exceed these values for
young children. For example,
a gel tray containing 5 ml of APF contains 61.5mg F (F is absorbed
more quickly when in acidic form.),
100ml of 0.2 or 0.4% F mouth rinse contains 91 or 97mg F and a
tube of fluoridated toothpaste contains as much as 230mg F.

16. POTENTIAL HARM
Probable toxic dose:
5 mg F / kg body
weight 61.5
mg F/ 91-97 mg F/
ACT
5 ml container of F
mouthrinse
Topical F,
12,300 ppm F
pH= 3.5
20 kg 6 year old,
PTD= 100 mg F
Symptoms:
1. Vomiting
2. Excess salivary and
mucous discharge
230 mg F/ 3. Cold wet skin
tube 4. Convulsion at
10 kg 2 year old toothpaste higher dose
PTD = 50 mg F

17. TEXT
Do not harm the patient
1. Probable toxic dose (PTD):
Sub-lethal toxic symptoms are manifested quickly after the dose and
consists of
1. vomiting
2. excessive salivation
3. tearing
4. mucous discharge,
5. cold wet skin
6. convulsions

18. POTENTIAL HARM
A serious systemic Counter Measures:
consequence is binding of F
to Ca which needed for 1. Emetics
heart function. 2. 1% calcium
chloride
3. Calcium gluconate
F 4. milk
F F
Ca
F Ca
Divalent cations
like Ca cause Ca
Ca precipitation, of F
and prevent
absorbtion in the
F intestine. F
Ca Ca F Ca Ca F
F F Ca F F Ca
Ca Ca

19. TEXT
Do Not Harm the Patient
2. Fluorosis:
Fluorosis occurs when teeth are developing.
The most critical ages are from 0 to 6 years. After 8 years, risk of
fluorosis is essentially past.
During the critical ages F intake in excess of 0.1mg/kg body
weight/day can lead to fluorosis.
This is roughly 1mg/day for a 1 to 2 year old or 1.5 to 2 mg for a 5
year old.

20. POTENTIAL HARM
DMFT FLUOROSIS
10
9 severe
8
moderate
7
6
mild
5
4 slight
3
2 0.0 0.5 1.0 2.0 3.0 4.0
PPM F IN DRINKING WATER
F in excess of 0.1mg/ kg body
weight = fluorosis

21. FLUOROSIS
F
F
Enamel prism
Excess F affects
mineralization of
developing teeth
Up to age 6 is the critical age for fluorosis.
After age 8, risk is past.

22. TEXT
Do Not Harm the Patient
2. Fluorosis:
Remember that all forms of F intake comprise the daily
consumption.
This includes
1. water intake (up to 1.5mg/day)
2. Foods (0.3 to 1.0mg) and especially significant in young
children
3. Swallowed toothpaste. Children under 2 years swallow 50% of
toothpaste during tooth brushing and at 5years, 25%, both of
which may amount to 1mg F/day.

23. FLUOROSIS
Daily F intake of a 20 kg 4
year olds with different water F
Maxium safe dose
for a 2 year old = 1
mg F / day 1 2 3 4 mg F
0.5
ppm
water F
1.2
ppm
water F
supplements toothpaste
Maxium safe dose fluids food
for a 5 year old = 2
mg F / day DW Banting
JADA
F in excess of 0.1mg/ kg body
weight = fluorosis 123:86,1991

24. FLUOROSIS
5 year olds swallow 25%
of toothpaste Children under 2 years
swallow 50% of
toothpaste
1 to 3 grams
“pea” size amount (0.5g) is
Toothpaste = 1 mg F /
recommenred for fluorosis
gram (1000 ppmF)
susceptible children.

25. mild moderate
pitting
severe

26. Prevention of Caries: 1st theory
1st theory :Deposition of fluorapatite (FHA) in sound tooth structure:
•Caries protection results from FHA being more acid resistant than
pure hydroxyapatite (HA).
•Deposition takes place when F replaces hydroxyl groups in HA.
•This can occur pre- or post-eruption at neutral pH, or post-
eruptively at neutral or acidic pH. At low pH, HA dissolves, then
re-precipitates as new crystals which are larger and more acid-
resistant due to higher FHA and lower magnesium and carbonate
content.

27. Prevention of Caries: 1st theory
Deposition of fluorapatite (FHA) in sound tooth structure:
Deposition of FHA is accomplished both by
1. systemic intake of F during tooth development
2. topical F administration after eruption. Professional topical F
treatments with concentrated acidulated phosphate fluoride (APF)
gels (2.72% APF gel contains 12,300 ppm F), is the most efficient
way to accomplish this, especially when applied to newly erupted
teeth (i.e., age 2 for primary molars; age 6 to 8 for permanent first
molars and anterior teeth; age 11 to 14 for permanent premolars and
second molars).

28. MECHANISMS OF F PROTECTION
DEPOSITION
Saliva (S) F F F F F
Plaque (P) F
F F F FF F
Tooth (T)
Topical F is
the best
Theory:
method for
Increase FHA deposition.
levels maximally in intact
dental surfaces.

29. DEPOSITION OF F
F FHA is more acid resistant than HA
F F
F
F
FHA
Neutral pH
remineralization
H+ PO4 H+
F
PO4 F FHA
F HA
F CO3
Ca Ca
pH 5.0
Mg
F
H+ Mg and CO3 P
do not
H+ reprecipitate Ca
FHA

30. DEPOSITION OF F
Best F uptake is late pre-eruption
Surface and early post-eruption
F build-up of
F
F F
F F F F
F F
F
F
F
Mature
Drinking Permanent Primary
enamel
water teeth teeth
F F
Ename F
F
F 3000 900
l fluid F
F
F No F 2000 600
Young enamel
This has better F uptake due to
more porosity Maximal F levels of in outer 5 microns

31. DEPOSITION OF F
Fluoride uptake is higher in a decalcified
PPM Fluoride area
3000
2000
1000 5 um
3000 ppm F
1500 ppm F
outer 2 microns = 6000 ppm
fluoride (max. uptake)
F
F
F F
Ca Ca Ca Ca Ca
As fluoride reacts strongly with calcium it
does not penetrate far into the tooth.

32. DEPOSITION OF F: F
Maxium uptake can
not be exceeded.
(3000 to 4000 ppm F
in outer 5 um)
The F-rich surface can be abraded
away.

33. Prevention of Caries
Bioavailability of F: A second theory of caries prevention asserts that
F in the vicinity of carious activity (in enamel fluid) prevents
dissolution of HA crystals. Although this mechanism requires only
low levels of F (less than 100ppm to as low as 1ppm), F must be
present when the acid challenge takes place and therefore must be
supplied continually.
Examples of topical applications which ensure bioavailability are
fluoridated drinking water and fluoridated dentifrices. A major source
of bioavailable F is residual F in plaque and pellicle. F in plaque
minerals such as CaF2 or calculus or in protein complexes is released
during bacterial acid production.

34. MECHANISMS OF F PROTECTION
BIOAVAILABILITY
Water fluoridation
is an example of a
source.
S SUGAR
F
P F ACID
T F
Theory:
Provide continual low level of F to
enamel fluid. The benefit occurs at
the time of decalcification.

35. BIOAVAILABILITY OF F
Decalcification of enamel crystals:
SUGAR S
Low level of F F saliva
H+ S
S
plaque
F F
H+
Decalcifying HA F Plaque and
F
crystals H+ enamel fluid
H+
F
H+
Intact HA
crystals
J Arends. JDR
69(SI):601,199
0

36. BIOAVAILABILITY OF F
F from plaque J Arends. JDR
fluid 69(SI):601,199
0
ACID
F F
F F H+
F F F
F
F F
H+
F
F
F F Protection from
dissolution Loosely-bound F
will eventually
F Stable FHA become stable
Loosely bound or FHA.
F
adsorbed F

37. BIOAVAILABILITY OF F
H+ FHA with no
F
F
H+ H+ H+
F F H+
F F
PO4
F F F
PO4
F
H+ H+
H+ F Ca
H+
Ca
Protection only H+
where is
F
Incomplete protection
J Arends. JDR
69(SI):601,199
0

38. BIOAVAILABILITY OF F
Effect on bacteria:
F H+ S
S
F
F F
H+ H+
F H+
H+ F
MS
F
H+
F
The presence of H+
fluoride at the time of
glycolytic activity will also
inhibit of plaque
acidogenesis.

39. SOURCES OF BIOAVAILABLE F
1. saliva
AC
T
2. Fluoridated
water 3. Home care products
Topical F 4. RESIDUAL
F
F F F F F S
ppm F in saliva
after drinking P
0.08 F F F F T
0.02 CaF2 precipitates in
Calcium plaque during topical
1 3 5 h Fluoride F treatment

40. BIOAVAILABILITY VERSUS DEPOSITION OF F
Rodent studies:
LESIONS (mean)
30
No FHA
MS
plus 8 DEPOSITION
FHA
F F
5
No FHA
sugar BIOAVAILABILITY
10 ppm F
added to
Larson RH. Caries
drinking water
Res 10:321, 1976

41. BIOAVAILABILITY OF F
Research evidence:
Add F:
F
calcium loss
F
5
HA
4
3 pH 5.0
2
1 pH
0 phosphate
0.05 0.1 1 5 calcium
F ppm in solution
JM Ten Cate. JDR
69(SI):614,1990

42. Prevention of Caries
Summary of preventive F procedures and recommendations:
The older view of caries prevention was that FHA deposition in non-carious
dental surfaces should be maximized by systemic F administration during
tooth development, and post-eruptively by topical F treatments.
It was believed that increased FHA provided increased protection against
caries.
Although implementation of high FHA deposition has proved beneficial, it
does not afford as much protection as bioavailable F. Moreover, the high
doses of F required, systemically or topically (which often becomes
systemic intake) are partly responsible for the increasing incidence of
fluorosis.

43. Prevention of Caries
Summary of preventive F procedures and recommendations:
Current clinical recommendations for preventive F measures are
1) to determine total F intake per day from all sources in order to assess
over or under F exposure
2) determine caries risk
3) institute a regimen commensurate with individual caries risk status which
emphasizes bioavailability of post-eruptive topical F (e.g. regular use of F
dentifrice and other home products if indicated)
4) administer professional topical F treatments, the timing of which should
also be gauged to caries risk (This may not be needed in low risk
individuals) and
5) administer systemic topical F if indicated. (The latter is currently under
review. Present Academy of Pediatric Dentistry recommendations are
presented below.

44. FLUORIDE SUPPLEMENTS
F
F in drinking water
AGE <0.3ppm 0.3- >0.6ppm
0.6ppm
6m-3y 0.25 0 0
3-6y 0.5 0.25 0
6-16y 1.0 0.5 0
Academy of Pediatric Dentistry current
recommendations

45. SUMMARY OF PREVENTIVE F
1. Determine F intake
2. Determine caries risk
3. Devise personalized plan based on risk
level.
4. Stress bioavailability of F.
5. Monitor F intake of young patients in
an effort to prevent fluorosis.

47. Thank you

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Dr Iyad Abou Rabii
Iyad.abou.rabii@qudent.edu.sa