Preventive Dentistry
Topical Fluoride
Lec.8 Dr. Jihan Abdulhussein
D- Restorative Materials Containing Fluoride
Fluorides releasing dental restorative material provide site specific
protection. In general, the rate of fluoride release from such materials is
not constant but exhibits a relatively rapid initial rate, which decreases
with time. When compared with non-fluoride releasing materials, fluoride
releasing materials may feature:
Greater longevity,
A reduced incidence of marginal failure,
An elevated concentration of fluoride in contingent plaque,
together with
An antibacterial action.
The purpose of adding fluoride to restorative material is to capture its
anticariogenic property. The fluoride ions are slowly released from the
materials. One difficulty with these materials is controlling the rate of
fluoride release. Fluoride may be released from dental restorative
materials as part of the setting reaction, or it may be added to the
formulation with the specific intention of fluoride release. Fluoride has
also been added to amalgam in an attempt to reduce the risk of recurrent
caries at restoration margins.
Fluoride containing restorative materials includes:
Glass ionomer cements
Resin modified glass ionomer cements,
Polyacid modified resin composites (compomers),
Resin composites,
Fissure sealants and
Dental amalgam.
Fluoride releasing components have included fluoroaluminosilicate
glasses (FAG), stannous fluoride (SnF2) and organic amine fluorides
(CAFH) etc.
F. Fluoride Containing Devices (Slow Release)
As a constant supply of low levels of fluoride, especially at the biofilm/
saliva/dental interface, being of the most benefit in preventing dental
caries, it is reasonable to expect a positive effect on caries prevalence of a
treatment able to raise intraoral F concentrations at constant rates, without
relying on patient compliance.
Considering that intraoral levels of F play a key role in the dynamics of
dental caries, it has been suggested that the use of controlled and
sustained delivery systems can be considered as a means of controlling
dental caries incidence in high-risk individuals. Thereafter, a topical
system of slow and constant F release was considered.
There are three types of slow-release F devices: the copolymer membrane
type, the glass bead, and recently, a third type, which consists in a
mixture of sodium fluoride (NaF) and hydroxyapatite.
Fluoride Ingestion and Toxicity of Professionally Applied Topical
Fluoride:
Fluoride applications must be carefully monitored because the potential
for over ingestion and toxicity exist. Fluoride is rapidly absorbed in the
gastrointestinal tract and young children are particularly vulnerable.
The exposure to and retention of fluoride foam by the patient may be
significantly less compared with APF gel application. Fluoride varnish
has a high fluoride concentration, but its safety is acceptable. Varnish is
fast setting, fluoride is slowly released, and a small amount is needed for
the complete dentition. Measurements of fluoride after topical treatments
with varnish show levels below those considered toxic. Consequently,
varnishes may be a better alternative to fluoride gels, especially for young
children. Topical fluoride application is not a risk factor for dental
fluorosis 1. When used at 6 months intervals, and 2. If precautions are
taken to minimize ingestion.
Self-applied fluorides
Self-application of fluoride is usually carried out with groups of persons,
usually children at one time, under only general supervision, in contrast
to professionally applied fluoride treatments which are expensive because
they depend upon one professionally trained person treating one person at
a time, with expensive equipment or supplies.
Requisites for self applied fluoride agents:
1. Should be completely safe.
2. Should be effective for preventing caries.
3. Method should be suitable for use by large groups and at a reasonably
low cost.
4. Should be acceptable to participants.
5. Should be easy to use to ensure compliance.
6. Should require few professional personnel.
7. Should be able to be supervised by non-dental personnel after short
periods of in-service training.
Fluoride dentifrices
Investigation in to effectiveness of adding fluoride to toothpaste has been
carried out since 1945 and covers a wide range of active ingredients in
various abrasive formulations.
Fluoride compounds that have been tested for caries-inhibitory properties
include
sodium fluoride,
acidulated phosphate fluoride,
stannous fluoride,
sodium monofluorophosphate and
amine fluoride.
Most toothpaste nowadays contain sodium fluoride or sodium
monofluorophosphate or combination of both as active ingredient,
Usually in concentration of 1000-1500 mg F/g.
Toothpaste is the most readily available form of fluoride, and tooth
brushing is a convenient and accepted habit in most cultures.
The general functions of toothpaste are:
1- Physico-mechanical function: by action of the abrasive materials
and toothbrush.
2- Chemical function: by reaction of fluoride with outer enamel
surface and antimicrobial effect.
Fluoride Concentration in Toothpaste
The caries preventive effect of low fluoride toothpastes intended for
children (< 1000 ppm) is inferior compared with the adult products
(which is 1500 ppm) Consequently, the benefits of caries prevention must
be balanced with the risk of fluorosis for children under 6 years old. So
use only a pea-sized amount for children under six years old also should
be supervised in the use of toothpaste to prevent swallowing.
High fluoride toothpastes with 2500–5000 ppm fluoride are available in
some countries and intended for:
Caries-active individuals over 16 years of age
For patients with special needs
For weak elderly people may promote root caries arrest.
Caries-active adolescents to reduce progression of approximal
caries.
The content of fluoride in dentifrices will decrease with increase in the
time of storage i.e 6 month or more.
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. The reduction
of dental caries was 24%–25%.
Fluoride mouthrinses
Frequent use of low concentration of fluoride is more cariostatic than less
frequent use of higher concentration of fluoride for topical application. In
areas where water fluoridation is not possible or not implemented, the
fluoride mouthrinses found to be an effective tool in prevention of dental
caries. For reasons of lowest expense, convenience in handling as well
avoidance of unpleasant taste, NaF became the most widely used of these
tested products in public health programs.
Indications
Patients who, because of the use of medication, surgery,
radiotherapy, have reduced salivation and increased caries
formation.
Patients with orthodontic appliances or removable prostheses,
which act as traps for plaque accumulation.
Patients unable to achieve acceptable oral hygiene.
Patients with extensive oral rehabilitation and multiple restorative
margins, which represent sites of high caries risk.
Patients needing fluoride in their home care but cannot tolerate a
custom-fitted tray.
Patients with gingival recession and susceptibility to root caries.
Patients with rampant caries.
Daily rinses should be recommended rather than a weekly regimen;as:
1. the daily procedure appear to be slightly more effective and also
2. as a practical consideration, it is easier for patients to remember and
comply with a daily procedure.
In all these instances, the rinses should not be used in place of any of the
other modalities of fluoride use but as part of a comprehensive,
preventive program that should also comprise plaque control, frequent
fluoride topical applications, the home use of a fluoride dentifrice, and
diet control.
In communities with fluoridated water supplies or with natural occurring
optimum fluoride level in drinking water, mouth rinsing programs would
give a super added benefit.
Recommendations:
Mouth rinses designed to be 10 ml rinse and spit out, 0.2 % of NaF
solutions are recommended (900 ppm F - ) for weekly fortnightly use,
while 0.05 % (225 ppm F - ) for daily use. Due to the risk of swallowing,
fluoride rinsing is not advocated to children below 6 years of age. The
caries reduction is about 26%-30%.
Fluoride Gels for Home Use
During the past 15 years, a number of fluoride gels have become
available as additional measures that may be used to help achieve caries
control. These procedures contain
1- 0.4% stannous fluoride (1,000 ppm fluoride)
2- 1.0% sodium fluoride (5,000 ppm) and are formulated in a non
aqueous gel base that does not contain an abrasive system.
Recommendation
The usage involves tooth brushing with gel (similar to using a dentifrice),
allowing the gel to remain in the oral cavity for 1 minute, and then
expectorating thoroughly. They may be considered as an alternative to the
use of fluoride rinses and an adjunct to the use of professional, topical
fluoride applications and fluoride dentifrices as a collective means of
achieving caries control in patients who are especially prone to caries
formation (e.g. patient with rampant caries). Like fluoride rinses, the use
of F gels is generally restricted to the period required to achieve caries
control. It should be stressed that fluoride gels should not be used in place
of fluoride
dentifrices. Proper use of these preparations in combination
with professional topical fluoride applications and the home use of
fluoride dentifrices may be expected to help achieve caries control in
caries-active patients.