Fluorides Delivery Methods
BDS IV Batch
Fluorides Delivery Methods
Fluorides can be delivered as :-
Topical fluorides are applied directly on the teeth. “Topically Applied Fluoride”
is used to describe those delivery systems which provide fluoride for a local
chemical reaction to the exposed surfaces of the erupted dentition. The delivery
system includes measures designed for professional application such as fluoride –
containing prophylactic pastes, solutions, gels, and varnishes as well as systems
deigned for unsupervised home use, such as fluoride dentifrices and rinses.
Indications for topical Fluorides
1. Caries-active individuals i.e. those with past caries experience or those
who develop new carious lession on smooth tooth surfaces.
2. Children shortly after periods of tooth eruption, especially those who are
not carries free.
3. Medication to reduce salivary flow or had undergone head and neck
4. After periodontal surgery when roots of teeth have been exposed.
5. Patients with fixed or removable prosthesis and after placement or
replacement of restorations.
6. Patients with an eating disorder or who are undergoing a change in
lifestyle which may affect eating or Oral Hygiene Habits conductive to
good oral health.
7. Mentally or physically challenged individuals.
Topical Fluorides products can be divided
into two broad categories:-
Professionally Applied Fluorides Product
Self Applied Fluorides Products
Professionally Applied Fluorides
These are the medicaments typically dispensed by dental
professionals in the dental office and usually involve the use of high
fluorides concentration products, ranging from 5000 and 1900 ppm which
is equivalent to 5-19 mgF/ml.
Bibby in 1942 was the first to demonstrate that the, repeated
application of sodium or potassium fluorides to teeth of children
significantly reduced their carries prevalence. This achievements became
the fore runner of many studies to test the effectiveness of various topical
fluorides and the effective methods of its application.
Topically fluoride application by a Dentist , Dental Hygienist or any
other Dental Auxiliary has become an established Caries-Preventive
Procedure in the Dental History. The three agents currently used as
professionally applied fluorides are:-
1. Neutral Sodium Fluoride (NaF)
2. Acidulated Phosphate Fluoride (APF)
3. Stannous Fluoride (SnF2)
The fluoride may be used in an aqueous solution, a viscous gel, a
prophylactic paste or as a dental varnish and can be applied using the
Paint on Technique or the Tray Technique.
Paint on Technique
Although it is not necessary to do a professional Prophylaxis prior to the application of a fluoride varnish, it is recommended that
the teeth be cleaned with a toothbrush.
Wiping with a cotton gauze is adequate in cases where there is no heavy plaque or debris.
The teeth should be lightly dried with air or a cotton gauze.
The varnish will adhere even if the teeth are moist.
Isolate the teeth (e.g. with cotton rolls) to prevent recontamination with saliva
A small amount of varnish (e.g. 0.5ml) is dispensed. The entire dentition may be treated with as little as 0.3-0.6 ml.
A small brush or applicator is then used to apply the varnish
The varnish will set on contact with the slightly moist teeth
The patient is instructed to avoid brushing for the rest of the day. Normal oral hygiene procedures can begin again the following
day As a result of the time needed for frequent reloading of the brush/applicator, Hodgson (2005) has suggested an alternative
technique utilizing a 5 ml plastic syringe. This method allows a more efficient application of the varnish which can be particularly
useful in cases where speed is important, such as with a difficult pediatric patient.
In order to be effective in decay prevention the varnish should be reapplied at least twice yearly.
How to Use Custom Fluoride Carriers (Trays)
Brush teeth thoroughly with soft toothbrush and regular toothpaste. Floss teeth using unwaxed
dental floss . It is very important to remove all food and plaque from between teeth before using
fluoride. Food and plaque can prevent the fluoride from reaching the surface of the tooth.
Place a thin ribbon of the fluoride gel into each upper and lower fluoride tray so that each tooth
space has some fluoride. Either 0.4% stannous fluoride or 1.1% sodium fluoride. The fluoride can
be spread into a thin film that coats the inside of the trays, by using a cotton-tipped
applicator, finger or toothbrush.
Seat the trays on the upper and lower arches and let them remain in place for 5 minutes. Only a
small amount of fluoride should come out of the base of the trays when they are
placed, otherwise, there may be too much fluoride in the trays.
After 5 minutes, remove the trays and thoroughly expectorate (spit out) the residual
fluoride. Very Important – do not rinse mouth, drink or eat for at least 30 minutes after fluoride
Care for Fluoride Carriers
• Rinse and dry the trays thoroughly after each use. Clean them by brushing
them with a toothbrush and toothpaste.
• Occasionally, the trays can be disinfected in a solution of sodium
hypochlorite (Clorox) and water. Use one tablespoon of Clorox in about
one-half cup of water. Soak them for about 15 minutes.
• If the trays become covered with hard water deposits, soak them in white
vinegar overnight and brush them the next morning.
• Do not boil the trays or leave them in a hot car as they may warp or melt.
Neutral Sodium Fluoride
Neutral Sodium Fluoride(NaF) was the first fluoride compound to be
used for topical fluoride application. A minimum of four applications of
with 2% Sodium Fluoride solution gives a caries reduction of about 30%.
Methods of preparation of 2% NaF
It is prepared by dissolving 20gm of Sodium Fluoride powder in one
liter(1000ml) of distilled water in plastic bottle. It is essential to use plastic
bottles because if stored in glass bottles it may react with silica and form
Silicon Fluoride thus by reducing the availability of free active fluoride of
Procedure for application of Sodium Fluoride
[ Knutsons Technique ]:
If the Sodium Fluoride reagent is pure and uncontaminated, the
solution has pH of 7. The treatment is carried under four series of
Teeth cleaned with aqueous pumice slurry
dry with compressed air
teeth isolated either by quadrant or by half mouth
2% NaF solution is painted on the air dried teeth so that all surfaces are
allowed to dry for 3-4 minutes
repeated for each of the isolated segments until all teeth are treated
2nd, 3rd and 4th NaF application, each not preceded by a prophylaxis, is
scheduled at intervals of approximately one week.
The fourth visit procedure is recommended for ages 3,7,11 and 13 yrs, coinciding with the
eruption of different age groups of primary and permanent teeth. Thus, most of the teeth will be
treated soon after their eruption, maximizing the protection afforded by topical application.
Mechanism of Action
NaF Hydroxyapatite crystals Calcium Fluoride
“Chocking Off Effect”
[as thick layer of formation of Calcium fluoride forms , it interferes diffusion of F from
NaF solution to react with hydroxyapatite and blocks further entry of F ions]
And acts as resorvior for F release [it is the reason allowed to dry for 3-4 minutes]
Calcium Fluoride Hydroxyapatite crystals Fluoridated Hydroxyapatite
increase of fluoride content on enamel surface resistance against caries attack
• Relatively stable when kept on a plastic bottles
• Taste well accepted by patients.
• Non- irritant to Gingiva
• Doesn't results in discoloration of teeth
• Once applied allowed to dry for 3-4 min so can pursue a multiple-chair
procedure in public health programme.
• The series of treatment must be repeated only four times in general age range
of 3-13 yrs rather than annual or semiannual intervals, therefore in public
health program , other group of children can be treated in intervening yrs.
• The only disadvantage is that the patient has to make four consecutive visits
within a short period of time.
Stannous Fluoride has been used at 8% and 10% concentrations in solutions
equivalent to 2 and 2.5% fluoride. Although 10% solutions used for adults and 8%
for children there is no any clinical difference between the two. However 8%
Stannous Fluoride is preferred.
Methods of Preparation of Stannous Fluoride
Solutions of Stannous Fluoride are not stable so soon after mixing
they become cloudy due to formation of Tin Hydroxide reducing the
agents effectiveness. Since, Stannous is believed to contribute to anticarries
benefits, aged solutions are considered to be clinically less effective so Muhler et
al recommended to use fresh solutions of Stannous Fluoride for each patients.
To prepare 8%Stannous Fluoride solution the content of one capsule which
is 0.8 gm(‘0’ no. gelation capsule) is dissolved in 10ml of distilled water in the
plastic bottles and shaken briefly.
Procedure for application of Stannous Flouride
[ Muhler’s Technique ]
Teeth cleaned with aqueous pumice slurry
Un-waxed dental floss is passed between the inter-proximal areas. (unwaxed dental
floss has been recommended and continues to be used because it is believed that
waxed dental floss may coat tooth surface and adversely affect fluoride uptake.)
Teeth are isolated and dried with air.
SnF2 is applied using the paint on technique and the solution is kept for 4 min.
Repeat applications are made every 6 months or more frequently if patients is
susceptible to caries.
Mechanism of Action
SnF2 Low concn tin Hydroxyphosphate oral fluids dissolve it
”metallic taste application”
SnF2 high concentration
Calcium tri-fluoro-stannate Tin tri-fluoro-phosphate
“Tin tri-fluoro-phosphate makes tooth surface more stable & less suspectibility to decay”
Calcium fluoride is also formed both at high and low concn which reacts with hydroxyapatite and
results in formation of fluorohydroxyapatite.
– Using 8% Stannous Fluoride solution at 6-12 months intervals conforms to
the practicing dentist’s usual patient – recall system.
– Administrative difficulties, particularly in public health programs.
– In aqueous solution the Stannous Fluoride is not stable.
– Since 8% solution is quite astringent and disagreeable in taste, its application
– The solution usually causes reversible tissue irritation manifestoed by gingival
blanching usually on individuals with poor oral hygiene.
– It usually causes pigmentation on teeth which has characteristic light brown
color. Staining usually appears in association with carious lesions, hypo
calcified regions and around margins of restorations.
Acidulated Phosphate Fluoride
Acidulated Phosphate fluoride was introduced in1960’s by Brudevold and his
co-workers at the Forsyth Dental Center, Boston, Massachusetts.
Methods of preparation of Acidulated Phosphate Fluoride
An aqueous solution of Acidulated Phosphate Fluoride is prepared by
dissolving 20gms of Sodium Fluoride in 1 l of 0.1 M phosphoric acid and then 50%
hydrofluoric acid added to adjust the pH at 3.0 and fluoride ion concentration at
1.23%. It is also called as Brudevold’s Solution.
For the preparation of Acidulated Phosphate Fluoride gel, a gelling agent
methylcellulose or hydroxyethyl cellulose is added to the solution and the pH is
adjusted between 4-5.
Procedure for application of Acidulated Phosphate
The preferred methods of application of using Acidulated Phosphate Fluoride is by
paint on technique and for gel preparation the tray technique accepted . It is recommended
for application at 6-12 months intervals.
The patient seated upright position in chair & Oral prophylaxis is done& teeth are treated completely.
Clinical application of APF gel by tray technique [disposable foam line tray is preferred]
To reduce ingestion a minimal amount of fluoride gel kept [coverage of tooth surfaces ,<5ml ]
saliva ejector is used to wipe out saliva and excess fluoride
reapplied after every 15-20 seconds so as to keep the teeth moist with fluoride solution through out 4
The patient is told not to swallow the gel but to exert slight pressure using the cheeks and the tongue
as well as light biting forces in order to cause the gel to flow inter-proximally. The fluoride gel should be
in mouth for 4 min and remaining oral fluids should be expectorated.
The patient is instructed not to eat drink or rinse his mouth for at least 30 min.
Mechanism of Action
Initially leads to dehydration & shrinkage of hydroxyapatite crystals
Dicalcium phosphate dihydrate (DCPD)
highly reactive with fluoride ion
Fluoride penetrates into crystals deeply through openings produced by shrinkage and leads to
formation of Fluoroapatite
The amount of Fluoroapatite deposited dependent on DCPD formation. For conversion of DCPD
into fluoroapatite deeper penetration and continuous supply of Fluoride required. Hence APF
soln was applied at 30 sec intervals and teeth kept wet for 4 min.
High fluoride concn and low pH, favours fluoride deposition, acidification of fluoride soln with
phosphoric acid found to suppress dissolution of enamel, as well as formation of calcium fluoride
The intermediate product Dicalcium phosphate & principal reaction product Calcium fluoride
• Requires only 2 application in a year and is thus suited for most dental office
• The gel preparation can be self applied and the cost of application also gets
• It has the ability to deposit fluoride in enamel to a deeper depth than a neutral
Sodium Fluoride or Stannous Fluoride.
• Acidulated Phosphate Fluoride is stable and need not be freshly prepared for
• Practical difficulties like the teeth should be kept wet for four minutes so
repeated application necessitates the use of suction thereby minimizing its
use in the field. This also increase the chair side time making this methods
• It is acidic, sour and bitter in taste.
• It cannot be stored in glass container.
Recommendation For Topical
According to Lecompte (1987), the recommendation for Topical Application of
high potency fluorides are:-
1. Not more than 2gm of gel per tray or approximately 40% of tray capacity should
be dispended. Even more conservative amount should be considered for small
2. To prevent the swallowing of saliva during 4 min topical application , use of
Saliva Ejector is recommended.
3. Following the 4 min of application procedure, the patient should be instructed to
expectorate thoroughly for from 30 sec-1 min, regardless the use of suction
cause the Expectoration is the only single most effective way of reducing orally
4. When utilising custom individually fitted trays for patients requiring daily or
weekly application of a high fluoride concentration product utilise only 5-10
drops of products per tray.
Self Applied Topical Fluorides
Self applied fluorides products are usually bought and dispended by the individual
patient but at the recommendation of a dental professional. These fluoride
products are of low concentration ranging from 200-1000 ppm or 0.2-1.0 mgF/ml.
The self applied fluoride usually are:-
Fluoride Dentifrices plays a significant role in in caries prevention since it
requires active participation by the patient to have any effect. It has been
demonstrated that the subject who brush twice a day or more with 1000 ppm
or, 1500 ppm or, 2500 ppm fluoride dentifrices, have significantly reduced caries
• The first clinical trial of a fluoride dentifrices was initiated by Bibby in 1942. The
active agent was Sodium Fluoride which had been added to a conventional
dentifrices containing Dicalcium phosphate as the abrasive.
• In 1945 Muhler et al reported a clinical trial that tested stannous fluoride in a
paste with a new calcium pyrophosphate abrasive system.
• In 1955, the stannous fluoride dentrifice became the the first dentrifice recognized
by FDA [Food and Drug Administration] as an effective tooth decay preventive
product which was later accepted by ADA [American Dental Association].
Fluoride Mouth Rinses
• The use of fluoride mouth rinses was first described by Bibby et al in 1946.
• In1979 the Council of Dental Therapeutics of American Dental Association acepted
Neutral Sodium fluoride and Acidulated Phosphate Fluoride mouth rinses as
effective caries preventive agents.
Sodium Fluoride Mouth rinses
• They are usually formulated at concentrations of either0.2%(900ppm F)
for weekly use or 0.05%(225 ppm F) for daily use.
• These rinses are intended to be used forcefully swishing 10ml of the liquid
around mouth for 60 sec before expectoring it.
Advantages of Daily Rinsing
• If the patient misses several sessions it is probably less critical than if he was on a
• Advantage of 0.05% Sodium Fluoride concentration is that it can be used to
produce topical as well as systemic benefit when indicated for individual patient.
Fluoride gels products includes neutral sodium fluoride and acidulated phosphate fluoride with a
fluoride concentration of 5000 ppm and stannous fluoride with1000 ppm. The stannous
fluorides products usually called gels, but actually are glycerin based solutions.
• The gels are applied either b y brushing or in trays.
• Professionally, applied fluoride given twice a year while self applied fluoride can be once a
day or more.
• Patients brush their teeth for 1 min with a gell or if trays used several drops are placed in
each tray and applied for 5 min. Patient should be informed to expectorate the gel and not to
swallow. And should rinse mouth after the application so as to minimize the risk of
swallowing gels by children and usually not recommended for children 6 years or younger.
Limitation of Fluoride Gels
They violate the principle of delivering low concentration of fluoride at
regular intervals. High concentrations of fluorides deposit calcium fluoride
on teeth rather than forming hydroxyapatite.
They present a toxicity hazard as relatively large amounts of fluorides are
given in uncontrolled manner to people of varying intelligence.
They are tedious to use on daily basis over a long period of time. However
they may be a value when prescribed professionally for use at home
especially for high risk subjects.
They circulate through the blood stream and are incorporated into the
developing teeth. They provide a low concentration of fluoride over a long period
of time. Some fluoride preparations provide both topical and systemic effects i.e.
when fluoride oral rinse are used they are swished for topical effects and
swallowed for systemic effects.
The different types of Systemic fluorides are:
I. Water Fluoridation
i. Community Water Fluoridation
ii. School Water Fluoridation
II. Salt Fluoridation
III. Milk Fluoridation
IV. Fluoride tablets/ drops/ lozenges
When fluoride appropriately used, is safe and effective agent that
can be used to prevent and control dental caries. Fluoride has been contributing to
improve the dental health of persons all over the world. Fluoride is needed regularly to
prevent and protect the teeth from being decayed.