Lec. 4-5-prevention

1. Preventive Dentistry
(Systemic fluoridation)
Observational studies revealed that fluoride taken during period of tooth
formation, and following eruption of teeth greatly reduces dental caries.
Systemic fluoridation can occur naturally ( by taking F from water and
environment ) or it may be applied artificially ( by adding of F to the water or
by using drugs ).
Dental fluorosis:
It is a developmental hypoplastic defect caused by excessive fluoridation
during the period of tooth formation. It is the 1st sign of chronic toxicity
appears clinically as a white spots or lines involving incisal edge or cusps of
posterior teeth or as a white opaque or brown area, in sever cases a corroded
appearance will occur.
Changes in human enamel have been examined using light and electron
microscopy. In principle increased exposure to F during period of tooth
formation leads to increase enamel porosity. In sever cases the fluorotic teeth
are highly porous because of increase of inter crystalline spaces; these spaces
are occupied by water and protein more than enamel.
The fluorosed teeth contain more immature protein. In more sever condition
changes involve enamel as well as dentin. After eruption of teeth, although the
surface layer is well mineralized it is susceptible to mechanical trauma leading
to break down of the outer enamel surfaces.
The exact cause of this hypoplasia is not clear it may be attributed to:
1- Altered metabolism in any or all phase of the enamel formation.
2- Altered ameloplastic activity.
3- Interference with crystal nucleation or growth.
4- Faulty enzymatic factor.
Factors affecting severity of dental fluorosis:
1- Fluoride concentration in drinking water: A direct relation ship is present
between dental fluorosis and level of F ingested.
2- Total amount of fluoride ingested: F ingested from water, food, inhalation
because of pollution all affect severity of dental fluorosis. The total amount of
water in take is affected by temperature. In hot water there is an increase
ingestion of F due to increase intake of water thus increasing the risk of dental
fluorosis, the opposite is true in cold area.
3- Duration of exposure to fluoride: Excessive intake of F for a long time as
eight years during the period of tooth formation may increase the severity of

2. dental fluorosis. Teeth mineralized early in life develop less dental fluorosis,
thus posterior are affected more than anterior. Also primary teeth are affected
less severely compared to permanent teeth, due to shorter maturation period. In
addition enamel maturation and calcification of primary teeth take place in the
intra uterine life, studies showed that the placenta do regulated the amount of F
reaching the fetus, also F concentrated in bones of the mother and the fetus
more than teeth.
4- Others: Dental fluorosis was found to increase among children with mal
nourishment. The exact cause for this is not clear.
The optimal level of fluoride:
Dean conducted his study among 7257, 12 – 14 year- old in seven cities in
USA. This was to explore the association between F level in drinking water and
severity of both dental caries and dental fluorosis. In measuring dental fluorosis
a special index was applied called Community Index of Dental fluorosis,
dividing the condition in to different categories according to severity by weight
(normal, questionable, very mild, mild, moderate and sever). While the DMF
index was applied for recording dental caries. Results showed a maximum
reduction of dental caries at a level of F of (1 ppm), at this level dental fluorosis
will involve 10 % of the population, but it is of the very mild type with no
practical aesthetic significance. Increasing F level in drinking water will cause a
dramatic increase in dental fluorosis but with no further reduction of dental
caries. Thus the optimal level is (the level of F in drinking water causing
maximum reduction of dental caries but with no clinical signs of dental
fluorosis).
Epidemiological and observational studies however showed that a more sever
dental fluorosis do develop some times in certain area of hot climate at one part
per million, thus the optimal level of fluoride was changed to 0.6 – 1.2 ppm
according to the temperature. In winter is 1.2 ppm and in summer is 0.6 ppm.
Communal water fluoridation:
It is the controlled or artificial adjustment of the level of F in a communal
water supply to achieve maximum reduction of dental caries and clinically no
significant level of fluorosis. Fluoride was 1st added to water supply in 1945 in
Grand Rapids (Michigan) while Muskegon was the control. Caries reduction
was reported to be 55%.
In USA, now more than 126000,000 people are receiving systemic
fluoridation. It is also applied in Europe and other countries.
Chemicals used are sodium fluoride, hydro fluoro silicic acid, sodium silico
fluoride etc. These materials are added to water by an automatic feeding
apparatus and concentration of F is continuously adjusted.

3. From different epidemiological observational studies, concerning water
fluoridation it was concluded that:
1- Artificial water fluoridation is effective in caries reduction in similarity to
naturally fluoridated area.
2- Caries reduction involved primary, permanent teeth as well as root caries.
The reduction is more in permanent teeth compared to primary because of their
shorter maturation period.
3- Communal water fluoridation is a public health measure. All people in the
community can gain the benefits from water fluoridation. No effort is needed by
recipients to prevent caries.
4- It is a cheap and successful measure of prevention.
5- A reduction in periodontal disease was also reported in fluoridated area.
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Alternative to Systemic Water Fluoridation
The communal water fluoridation is a successful method for the prevention
of dental caries. In presence of objection against this method or there is no
piped water supply as in rural area, there are alternative methods to provide
systemically. These are alternatives as:
1- School water fluoridation (or home water fluoridation).
2- Dietary fluoride supplements by:
A- Fluoridated tablets (drops or lozenges).
B- Fluoridated salt.
C- Fluoridated milk (or juice).
School Water fluoridation:
This method was first applied in USA, 1954, in which the F content of the water
supply was adjusted for the prevention of dental caries. The optimal level of F
here is about 4.5 times the optimal amount in the community.
This is because:
- Children spend only a part of their total waking hours in schools.
- They enter the school at 6- year of age, thus the incisors are no longer at risk
of dental fluorosis.
- Only a part of daily water intake is consumed.

4. For all of the above and to compensate for the part exposure to F, the level of
fluoride in school water supply increased.
Special equipment can be used for the addition of F, which should be adjusted
continuously by well trained employee.
Advantages of school water fluoridation:
- Technically feasible.
- Low in cost.
- No effort is needed by the recipients.
A maximum benefit of systemic water fluoridation is by early intake of F
from the first years of life till 13-15 yeas of age.
The home water fluoridation is also of beneficial in caries prevention; however
the level of water is in similarity to communal water fluoridation.
Fluoridated supplements:
1- Tablets, drops and / or lozenges:
This is especially prescribed for children with high risk to dental caries,
handicapped children, or those with serious illness as blood disorder.
This method is an effective measure to prevent or reduce dental caries
provided to taken daily from birth, or the first years of life till 13- 15 years,
caries reduction can reach 50 -80%. A variety of supplements are present in
form of NaF
- Liquid form for infants and young children, concentrations are 0.125 mg F/
drop, 0.25 mg F/ drop, and 0.5 mg F/ drop.
- Liquid form with vitamins as A, D, C, E, E, B1, B3, B6, B12 and Iron,
prescribed to mal nourished children only.
- Tablets with or without vitamins, it can chewed then swallowed.
- For school children more than 6 years of age a mouth wash fluoride of 5 ml
can be used. The child is asked to rinse his mouth first for one minute then
swallow to have a topical and systemic effect.
Note: Supplements should be given daily, Not with milk
In prescription of F tablets several important factors should be taken in
consideration.
- F content of the water supply, (communal or bottled water). Applied only in
non F area or those with low F level.

5. - Age of the child.
- Co operation of parents.
Fluoridated tablets (drops ). as NaF :
Age Conc.
0-2 yr. 0.25 mg
2-4 yr. 0.5 mg
4- yr. 1.0 mg
Another Program:
- Started at 3 years of age give 0.5 mg/day till 13 – 15 years.
- In presence of dental caries (0.25 mg/day till 3 years) then 0.5 mg/ day till 13-
15 years.
Instructions:
1- Given daily (once or twice).
2- Tablets crushed between teeth.
3- Each bottle contains not more than 264 tablets, to avoid acute toxicity after
the accidental ingestion of fluoride tablets.
4- Dentifrices used should be without F, or with a low concentration.
2- Fluoridated Salt:
It was introduced first in Switzerland, 1955. It is considered next to water
fluoridation regarding caries reduction. F is added to salt inform of NaF or
CaF2 in different doses, 200, 250, 350 mg F/ kg of salt for domestic use or
bakeries. Advantages of salt fluoridation are;
- low cost
- ease of implementation
- no personal efforts is needed.
- Effective in caries reduction for permanent as well deciduous teeth
Disadvantage; children would start to use salt too late in life, or they used to
take small amount of salt.

6. 3-Fluoridated milk:
Human and bovine milk contain a low level of F about, 0.03 ppm. Milk is a
good food for infant and children, it is a suitable vehicle for supplementary F to
children, it is an excellent source for calcium and phosphorous in addition to
vitamin D. Milk is essential for development of bones and teeth.
Fluoridated milk can be used in home and school programs, with caries
reduction of 70%.
The disadvantages of milk fluoridation are the high cost. Some children dislike
milk, for them a fluoridated juice can be used.
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Topical fluoride therapy:
This term refers to the use of systems containing relatively large concentration
of fluoride applied locally or topically to erupted tooth surfaces in order to
prevent or arrest dental caries. The primary reactions product involved the
transformation of surfaces hydroxyapatite to calcium fluoride.
Calcium fluoride is a loosely bound fluoride, dissolved rapidly and there for to
increase fixation of fluoride it needs to be applied frequently and continuously.
The use of topical fluoridation started in 1940, to control dental caries. The best
time of application of topical agents is in the post eruptive maturation period
that is the two years after eruption. Ionic exchanges continue between the oral
environment and outer enamel surface.
Topical fluoride therapy involves:
1- Self – applied fluoride.
A relatively low concentration of fluoride applied by individuals themselves.
The concentration of fluoride is about 1000 ppm. This system includes:
- Dentifrices
- Mouth rinses
- Fluoridated gel
Agents can be used once or twice a day, and a combination of two types can be
applied.
2- Professionally applied fluoride.
It is the periodic application of a high concentration of fluoride to the erupted
teeth by dentists or dental hygienist every 3, 6, or 12 months. The
concentrations of fluoride are 9000 – 19000 ppm, it may reach for some agents

7. to 23000 ppm. Agents can be applied inform of solutions, gel, varnishes,
prophylactic pastes or pumice.
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Self – applied fluoride:
1) Fluoridated dentifrices
The first clinical trail of fluoridated dentifrices initiated by Bibby 1942, the
active agent was sodium fluoride, and the abrasive was dicalcium phosphate
(DCP). The general functions of these dentifrices are:
1- Physico – mechanical function; that is by the action of the abrasive materials
and the toothbrush.
2- Chemical function; that is by the reaction of fluoride with the outer enamel
surface and the antimicrobial effect.
Types of fluoridated agents in dentifrices include;
- Sodium fluoride (NaF).
- Stannous fluoride (SnF2)
- Sodium monofluorophosphate (MPF)
- Amine fluoride
- Combination of NaF and MPF
The range of fluoride concentrations in these agents is 525 – 1450 ppm. The
content of fluoride in dentifrices will decrease with the increase in the time
of storage i.e six months or more. The type of fluoride agent used must be
compatible with the constituents of the tooth paste especially the abrasive
systems.
Following brushing there will be retention of fluoride in the oral fluid and
dental plaque. Fluoride ions released gradually in the saliva and there by
maintains a degree of protections against caries.
The increase in the frequency of brushing will increase the benefits of fluoride.
Studies recorded caries reduction by using fluoridated dentifrices about 25 –
30%.
2) Fluoridated mouth rinses
It was started in the early 60,s of the last century. It can be used in the
following conditions:
- Primary preventive programs for children and adults

8. - In subjects with high risk to dental caries.
- Patients with rampant caries.
- Patients with hyposalivations or xerostomia.
- Patients with sensitive teeth due to tooth wear as (abrasion, attrition, erosion)
or because of exposed root.
- Patients with periodontits and root caries.
- Patients with orthodontic appliance.
Types of agents used:
1- Sodium fluoride, it is the main type used in neutral or acidified forms in a
water vehicle.
Concentrations 0.2% (900 ppm F) applied once a week.
0.05% (225 ppm) applied daily.
2- Stannous fluoride Concentration 100, 200, 300 ppm.
3- Amine fluoride or ammonium fluoride.
A 10 ml of rinse used by forcefully swishing of liquid around the mouth for one
minute then expectorate.
Fluoridated mouth rinse should not be given
1- To children under six years of age, as they cannot control muscles of
swallowing.
2- Children living in fluoridated area or receiving fluoride supplements.
Studies reported a caries reduction about 30%.
Note: Fluoridated mouth rinses should not substitute fluoridated dentifrices,
rinses is usually supplement toothpaste.
3) Fluoridated Gel
It is used in home programs.
Types of agents:
- Sodium fluoride or acidulated phosphate fluoride (concentration 5000 ppm).
- Stannous fluoride (0.4%).

9. These can be applied using special tray or applied directly to teeth by
toothbrush. Applied for 1- 5 minutes, then expectorate. Patients advised not to
rinse by water or eat or drink for at least 30 minutes.
Indications for use:
- Patients with rampant caries.
- Patients with xerostomia.
- Patients with sensitive teeth due to tooth wear as (abrasion, attrition, erosion)
or because of exposed root.
- Root caries.
It can be used for four weeks course, when the onset of the disease is stopped
the patient can switch back to mouth rinse.
Fluoridated gel is not recommended for children under 6-years of age.
Note: It is used in combination with dentifrice, and not preferable to be used
with mouth rinse.
Professionally applied fluoride.
Medicaments typically dispensed by dental professional in the dental office to
prevent or arrest dental caries. Materials applied are in forms of solutions, gel,
foam, varnishes or pumices. Different agents are available as:
- Sodium fluoride
- Stannous fluoride
- Potassium fluoride
- Zirconium fluoride
- Titanium fluoride
- Others.
The concentration range of fluoride in these agents is 9000 – 22000 ppm.
Method of application:
Techniques followed for application of fluoride in the dental office are:
- Paint on technique, by which fluoride material applied to teeth by cotton
applicator of brush.

10. - Tray technique: a small amount of fluoride is added to a tray then inserted in
the patient mouth. Trays come in different shapes and types as foam lined or
paper, custom vinyl etc.
For both techniques:
- Teeth are cleaned first (scaling and polishing) to remove dental plaque,
calculus, stain and debris. These may interfere with the uptake of fluoride ions
and reduce its effectiveness.
- Teeth are isolated using cotton roll and saliva ejector. The head of the patient
tilted forward to avoid accidental swallowing of the materials.
- The fluoridated agent applied following dryness of teeth for 1 – 4 minutes.
The amount of agent used must not exceed 4 ml to prevent acute toxicity.
- Use un waxed dental floss to push the material between teeth.
- Following treatment ask the patient to expectorate several times.
- Instruct the patient not eat or drink for at least 30 minutes.
Indications
In general materials indicated to be use in;
- Prevention of dental caries
- Rampant caries.
- Sensitive teeth and root caries
Sodium fluoride (NaF)
These materials are available in form of powder, solution or gel. The
concentration of fluoride is 2 %. When powder is used 0.2 gram dissolved in 10
ml distilled water.
These agents have a basic pH, chemically stable when stored in plastic or
polythene containers, a flavoring and sweetening agents can be added.
These materials are not irritant to the gingival, and do not cause discoloration to
teeth.
Acidulated phosphate fluoride
The success of any topical fluoridated agent depends on its capability of
depositing fluoride ions in the enamel as fluoroapatite and not only calcium
fluoride. Fluoroapatite crystals are stable not like calcium fluoride.

11. There are two ways of speeding to the reactions that lead to formation of
fluoroapatite.
1- Increase concentration of fluoride ions in the agent.
2- Lowering the pH, that is making the solution more acidic.
Increase the concentration of fluoride ions lead to formation of calcium fluoride
and phosphate, while the presence of acid leads to break down of the outer
enamel surfaces (hydrolysis of hydroxyapatite and release of calcium and
phosphate)
In both reactions phosphate formed. The increase in phosphate concentration
causes the shift in the equilibrium of the reaction to right side that is in the
direction of formation of fluoroapatite as well as hydroxyapatite crystals. In
another word, the increase in the concentration of fluoride ions and lowering the
pH in presence of phosphate lead to increase deposition of ions in form of
fluoroapatite crystals (ie increase fixation of fluoride ions in the enamel
surface).
Acidulated phosphate (APF) is composed of NaF to which acid is added. The
concentration of fluoride is 1.23%, the acid is in form of orthophosphoric acid
the pH is 3.2.
APF comes in form of solution, gel and foam, to these coloring and flavoring
agents added. It is chemically stable when stored in plastic containers, and does
not cause discoloration to teeth.
The gel is more preferable than solutions as it increase the time of retention of
the materials on the tooth surface. The gelling material is in the form of carboxy
methyl cellulose. Another type of gelling material added known as thixotropic
gel, it is a gel like material under pressure behaves like solution and flow
between teeth, at the same time it became viscous by low pressure thus will not
flow behind the tray to enter the patient throat.
Stannous fluoride (SnF2)
It contains cation (stannous) and anion (fluoride), both react with enamel
surface forming calcium fluoride, stannous fluoroapatite and hydrated tin oxide.
Ca10(PO4)6(OH)2 + 19 SnF2 10 CaF2 + 6Sn3F3PO4 + SnO.H2O
These complex agents increase resistance of enamel to acid dissolutions.
Stannous fluoride used in form of solutions. It is available in powder that is
prepared by dissolving appropriate weight in distilled water. For children the
recommended concentration of stannous fluoride is 8% (dissolve 0.8 mg in 10

12. ml of distilled water). For adolescents and adults the recommended
concentration is 10 % (dissolve 1 mg of powder in 10 ml distilled water).
Advantages of SnF2
1- Effective in preventing dental caries, by the increase of the resistance of
enamel against acid.
2- Re mineralization of initial carious lesion.
3- De sensitization of teeth.
4- Antibacterial, includes both specific antibacterial effect against cariogenic
bacteria, and non specific effect against other type of bacteria.
5- Has an additive effect by tin ions in addition to fluoride ions.
Disadvantage
1- Not stable in aqueous solution, it under goes rapid hydrolysis and oxidation
to form stannous hydroxide and stannic ions. These may reduce the
effectiveness of fluoride. Thus, stannous fluoride solution need to be freshly
prepared.
2- Un pleasant taste, it has metallic astringent taste.
3- Reversible irritation to gingival, as gingival bleaching may occur. It is not
recommended to be used in sever gingival inflammation.
Indication of use
1- Primary preventive programs (once or twice a year).
2- High risk group and rampant caries (every 3 or 6 months).
3- Initial caries (3 or 6 months)
4- Desensitizing agents (once a week then every 3 – 6 months)
5- Patients with xerostomia ( 3- 6 months).
6- Patients with hypoplasia or calcifications (as amelogensis imperfecta or
dentionogensis imperfecta).
7- Root caries.