Dental Public Health Al Azhar University Gaza Lama k El Banna

2. College of Dentistry
Dental Public Health
03Prevention of Dental Caries
Dr. Hazem El Ajrami
Master Degree in Orthodontic & Pedodontic

3. The only topical method with real effect in
caries control is the topical application of fluoride
in one way or the other.
Prevention of dental caries with fluoride:

4.  What is fluoride?
 It is one of the halogens.
 It is the most active element of this group. It is
not present in the free form.
 Fluoride is the combined form of the free
element. It is difficult to obtain a sample of
calcium compound from a natural source in a
completely fluoride free condition.
 It is present in soil, seawater, rainwater,
seafood, etc.
 Fluoride is the only proved diet substance to be
of anti-cariogenic benefit for humans.

6.  Fluoride can be used to control dental caries
either by:
 Systemic route, i.e. by ingesting fluoride.
 Topical application.

7.  Mode of action of fluoride:
The role played by fluoride in the control of
dental caries is mainly as
follows:
1) Ionic exchange of fluoride with the hydroxyl
group of calcium hydroxyapetite in the surface
layers of enamel changing it into fluoroapetite,
which is less soluble in acids.
2) Enzymatic inhibition interfering with the
breakdown of glucose to lactic and pyruvic acid.
Both phosphatase and anulase enzymes are
inhibited by fluoride.

8. 3) Bacterial inhibition, fluoride has a direct
inhibitory effect on the bacteria of the dental
plaque.
4) Fluoride has the ability to precipitate minerals
from saturated solutions. As saliva is saturated
by minerals, fluoride favors the precipitation of
the calcium phosphate on the surface of enamel,
so it aids in remineralization of partially
demineralized enamel in early caries.

10. 5) Fluoride lowers free surface energy. This will
decrease the plaque accumulation on the treated
enamel surface.
6) Action on tooth size and morphology: in
communities with fluoridated water supply,
there is a trend towards shallower fissures and
lower cusp height and smaller tooth size. This
will decrease caries susceptibility.

11.  Sources of fluoride:
 Humans obtained fluoride from three sources:
water, foods and air. Two of them, water and
food, may contribute significant amounts to the
daily intake.
 Water from deep wells and artesian wells
usually provide high natural fluoride
concentration.
 Most vegetables, fruits and dairy products
contain low amount of fluoride.
 Meat also contain little fluoride but seafoods
(fish sp. salmon and sardines, shrimp, crab, etc)
may contain 2.5 ppm.

12.  Most beverages contain amounts of fluoride
especially tea.
 Fruit juices and soft drinks are generally low in
fluoride, but the fluoride content of the water used
in the preparation of such beverages or in the
cooking of food will be reflected in the fluoride
concentration of the final product.
 The total amount of fluoride consumed daily will
depend upon both the concentration of the fluoride
in the water and food as well as the amount
consumed.

13.  The recommended optimal fluoride doses for
community water supplies vary with the annual
mean of the maximum daily temperature (0.7 to
1.2 ppm).
 The average diet provides 0.2-0.3 mg of fluoride
daily.

14.  Fluoride content of enamel:
 Tooth enamel is composed mainly of hydroxyapatite
and a little proportion of calcium carbonate. Traces
from other elements present either incorporated in the
structure of the crystals or concentrated on the enamel
surface.
 It was noticed that there is an inverse relationship
between fluoride and carbonate concentrations in
enamel.
 Fluoride is concentrated at the surface and decreases
towards the DEJ junction.
 Its concentration in surface enamel reaches 2000-3000
ppm in water-fluoridated areas.

15.  Uptake of fluoride by the teeth:
Fluoride is incorporated in enamel and dentine in
two stages:
I. Before eruption:
During calcification, traces of fluoride incorporated
into the crystalline structure of appetite lattice.
Further amounts of fluoride are taken up by the
external enamel surface from the surrounding tissue
fluids before eruption.

16. II. After eruption:
Enamel surface continues to pick up fluoride
derived from diet, water and saliva. The post-
eruptive acquisition of fluoride continues
throughout life and is directly proportional to the
concentration in food and water ingested.

17.  Toxicity of fluoride:
 High doses of fluoride are toxic and may be
lethal. Fortunately, this is rare and only few
accidental cases are reported. The severity
depends upon the amount ingested and the
duration of intake.
 Chronic fluorosis results in skeletal or dental
changes.
 If fluoride was ingested during the tooth
developmental period at levels injurious to the
ameloblasts.

18.  Mottled enamel may result with various degrees
of severity when water fluoride concentration is
(6-8 ppm).
 Later in life, the ingestion of high levels of
fluoride may result in bony deformities, joint
fixation and calcification of the ligaments.

20.  Methods of providing fluoride:
This can be achieved either by ingesting
calculated amount of fluoride to be incorporated
in the developing teeth, or topically applying
fluoride preparations on exposed tooth surfaces to
increase their resistance to cariogenic processes.

21. A. Systemic fluoride:
1. Water fluoridation:
There is an inverse relationship between the
fluoride level in drinking water supplies and the
incidence of dental caries. There is also a direct
relationship between fluoride level and the
number of caries free individuals in the
community. This beneficial effect continues
associated with increased fluoride levels of about
1-1.5 ppm. It should be noticed that there is also a
direct relationship between fluoride level and the
incidence of mottled enamel. A fluoride
concentration of 1 ppm was found to be optimum
regards effective anti-caries effect and lower
mottled enamel.

24.  In areas of communal water supply with less
than 1 ppm fluoride, the concentration of
fluoride is adjusted to reach this level. Later
fluoridation is the most economical way for
combating dental caries at the community level.
 It is recommended that optimal dose of fluoride
ingested daily in children from 0.5-1.0 mg
fluoride (WHO).

25.  So this 1 ppm fluoride concentration is suitable
for countries with cold weather whereas in
countries with hot weather the concentration of
fluoride in public water supplies should be lower
and this depends on the daily water consumption
which is usually double or triple them that of cold
weather.
 In Egypt the fluoride concentration of Nile water
is about 0.36 ppm in which is considered
optimum.

26. 2. Fluoridation of school water supply:
Where fluoridation of communal water supply is
not possible fluoridation of school water supply
can be approached. School children are exposed
to the benefit of fluoridation only during school
days and hours. In this case higher fluoride
concentration up to 5 ppm have been tested and
proved effective in caries control. The decrease
in DMFS is about 40% with no evidence of
dental fluorosis.

27. 3. Fluoride supplements:
When fluoridation of water supply is not feasible
or possible, fluoride supplements can be resorted
to. This can be in the form of fluoride tablets,
drops or syrups. Studies have shown
considerable reduction in dental caries in
deciduous and permanent dentition when
consumption of fluoride has been started early
enough. The usual dose is 0.5 mg F/day for
children up to 3 years of age and 1.0 mg F/day
for children over 3 years of age.

29. The fluoride tablets usually contain 1.0 mg F,
to be crushed in water or fruit juices. Fluoride
administration should continue until the age of
complete crown formation of the second permanent
molar, i.e. about the age of 10 years. Fluoride
preparations should be kept out of reach of children
to avoid over dosage. Fluoride tablets disguised as
sweets are not advised.

30. 4. Fluoride incorporation in various foods:
To make fluoride administration, a personal
choice, incorporation of fluoride in certain
foods of common use such as salt, milk, bread,
rice, etc, the fluoride enriched foods are usually
available on request. It is difficult to adjust
fluoride concentration to satisfy the individual
personal intake as the consumption of these
foods may vary significantly from one person to
another. A careful regulation of the prescribed
daily dose and a constant cooperation by the
parents is required.

31. B. Topically applied fluorides:
The topical application of fluoride can be carried
out either by the patient himself or by members
of the dental profession.
1) Self administered fluoride applications.
2) Professionally applied fluoride.

32. 1) Self administered fluoride applications:
A. Fluoride tooth pastes (dentifrices): (Discussed
before).
B. Brushing or rinsing with fluoride solution:
Studies have shown that regular rinsing or
brushing (every week) with 0.2% sodium
fluoride will reduce dental caries incidence. The
principle to be noted is the frequent rinsing with
very dilute fluoride solution. This is to be done
after the routine tooth brushing to obtain clean
tooth surface and direct access to the enamel
surface.

33. • Highly diluted solution (0.02%) can be used
daily for patients showing high caries
susceptibility. Studies on supervised month
rinsing can be carried out in schools and
evidence of substantial success has been
obtained.

34. C. Fluoride gel:
This is usually commercially available product
containing 1.23% fluoride. It is widely used. The
gel has added flavours. It has to be loaded in a
special applicator to hold the gel in place for
about 4 minutes. With some applicators, the
whole mouth can be treated at once.
D. Fluoride dental floss:
Dental floss (unwaxed) impregnated with
fluoride is a valuable topical fluoride vehicle.
Flossing will result in a significant uptake of
fluoride and a reduction in the colonies of
microorganisms on the proximal tooth surfaces.

37. 2) Professionally applied fluoride:
It is very beneficial in reducing dental caries
particularly for children who live in area with
low fluoride concentration in the drinking water.
Different forms of fluorides have been utilized
for the topical use.
I. Sodium fluoride:
The recommended procedure of 4 applications of
a 2% sodium fluoride solution, one week interval,
between every application result in an 40%
reduction in dental caries incidence. These 4
applications are considered a single application
and have to be applied every year.

38. II. Stannous fluoride:
Single annual application of 8% stannous
fluoride gives about 65% reduction in caries
incidence. Stannous fluoride solution is
unstable. It has a short shelf life, so it has to be
prepared freshly for each application by
dissolving 0.8 gm. of stannous fluoride in 10 ml
distilled water. The solution has a disagreeable
astringent taste, and it discolors decalcified
enamel.

39. III.Acidulated phosphate fluoride:
Combination of sodium fluoride with
phosphoric acid; 1.23% sodium fluoride in 0.1
M orthophosphoric acid produces an acidulated
phosphate fluoride mixture which when applied
topically to the teeth of children on an annual
basis has decreased caries from 50-70%. This
agent is stable, so it does not have to be
prepared freshly for every treatment as in cases
of stannous fluoride; also, not discolor
decalcified enamel.

40.  Procedure for applying fluorides
topically:
1) Stannous fluoride:
A. A thorough prophylaxis should be performed;
each available tooth surface should be cleaned
and polished with pumice and rubber cup. It is
preferable to add one drop of 8% stannous
fluoride solution to the polishing paste.
B. The upper and lower teeth on one side are
isolated at a time, this is achieved with a long
cotton roll in the upper and lower buccal sulci
and a short roll in the lingual area. A saliva
ejector helps to keep the area dry. The teeth are
then air-dried.

41. C. An 8% stannous fluoride solution is freshly
prepared and applied to all surfaces of the dried
teeth with a cotton applicator. The teeth are kept
moist with the solution for 4 mn. by applying it
every 15 to 30 sec.

42. 2) Acidulated phosphate fluoride:
The same technique as for stannous fluoride.
3) Sodium fluoride:
 A thorough prophylaxis is performed.
 Teeth on one side are isolated as mentioned
before.
 Teeth are then dried and the 2% sodium
fluoride solution applied to each tooth surface
including the interproximal surfaces with a
cotton applicator. The solution is allowed to
dry on the teeth for 3 to 5 mn.

43.  On 3 subsequent visits, usually one week apart,
the same procedure is repeated with the
exception that prophylaxis is omitted and these 4
times are considered one application. The teeth
have to be treated every year.

44. Sodium fluoride has a good shelf life; the
solution can be kept for a long period of time
without deterioration. For those children to whom it
is difficult to apply fluorides every year; it is
customary to treat the teeth with topical fluorides at
3,7,10 and 13 years of age. This is to insure that all
the primary teeth and most of the permanent ones
receive the beneficial effect of fluorides just after
their eruption.

45. 4) Prophylactic paste:
The routine use of prophylactic pastes
containing fluoride in the dental office is
expected to increase the fluoride content of
surface enamel and consequently, its resistance
to add attack. This will be advantageous when
carried out every six months as part of the
regular dental examination. The most recently
available are stannous fluoride - zirconium
silicate paste and an acidulated phosphate
fluoride - silicone dioxide paste.