Dental Health and Fluoride Treatment
Fluoride is a mineral that occurs naturally in many foods and water. Every day, minerals are added to and lost from a tooth’s enamel layer through two processes, demineralization and remineralization.
Minerals are lost (demineralization) from a tooth’s enamel layer when acids — formed from plaque bacteria and sugars in the mouth — attack the enamel. Minerals such as fluoride, calcium, and phosphate are redeposited (remineralization) to the enamel layer from the foods and waters consumed. Too much demineralization without enough remineralization to repair the enamel layer leads to tooth decay.
Fluoride helps prevent tooth decay by making the tooth more resistant to acid attacks from plaque bacteria and sugars in the mouth. It also reverses early decay. In children under six years of age, fluoride becomes incorporated into the development of permanent teeth, making it difficult for acids to demineralize the teeth. Fluoride also helps speed remineralization, as well as disrupts acid production in already erupted teeth of both children and adults.
Optimizing a fluoride protocol for individuals at dental caries risk is the most important measure that can be done to prevent future and halt current disease. However, fluoride therapy remains complex and controversial. Since the introduction of water fluoridation, fluoride supplements, and topical fluoride therapies in the late 1940s, the mechanisms of action, dosage and delivery systems have been debated and have evolved.
Originally, the mechanisms of fluoride action were ascribed solely to reducing enamel solubility. Now, other mechanisms such as fluorides effect on remineralization and its effect on bacterial metabolism also are recognized. Similarly, the initial dosage of fluoride supplements was empirical, based on simulating fluoride exposure from optimally fluoridated water. As a result of epidemiologic studies showing mild fluorosis, which is the developmental disturbance of dental enamel caused by excessive exposure to high concentrations of fluoride during tooth development, in some children with the original dosage and the fact that fluoride is now a ubiquitous part of a child’s diet, the fluoride supplement dosage has been altered several times over the past 30 years. These issues of dosage are further compounded by epidemiologic studies showing changing prevalence of caries and fluorosis.
Topical fluoride use in preschool children, as well, has evolved. New modalities, such as fluoride varnishes, have become more prevalent for office treatment for children because of the safety of premeasured doses, ease of application and better patient acceptance. We will explore this further when we look at the forms of fluoride.
Overlaying both the issues of topical fluoride therapy and fluoride supplement use is the current focus on individualized therapy for patients based on caries risk. One should no longer prescribe fluoride supplements or perform a professionally applied topical fluoride treatment without considering an individuals caries risk. Recent recommendations suggest limited use of fluoride for those at low caries risk, but significantly more frequency and intensity for those at high risk.
This course will explore the forms of fluoride and their appropriate uses. It will also explore options, based on efficacy for systemic fluoride, office treatments and home-use fluoride products.
Fluoride therapy is the deliver of fluoride to the teeth topically or systemically in order to prevent toot decay, also called dental caries, which result in cavities. Treatments in a dentists office contain a much higher level of fluoride than the amount found in toothpastes and mouth rinses.
Currently available fluorides include sodium fluoride, sodium monofluorophosphate, acidulated phosphate fluoride and stannous fluoride. In addition to its use as an caries preventative to help demineralization and acid remineralization, fluoride is used for the treatment of dentinal hypersensitivity.
Systemic delivery involves both intentional sources of fluoride using fluoriadated water and fluoride supplements and unintentional sources such as naturally occurring fluoride in well water, fluoride toothpaste, brewed tea, bottled water, drinks and goods processed using fluoidated water, and foods such as fish. In addition, certain medications contain fluoride. Systemic fluoride can also be delivered via salt, tablets, or drops which are swallowed. Tablets or drops are rarely used where public water supplies are fluoridated.
Fluoridated water High fluoride level well water
Fluoide supplements Foods containing fluoride
Fluoidated salt Home-use topical fluoride
Fluoridated foods High fluoride level bottled water
Since water fluoridation was first introduced there has been a substantial decline in caries rates. Water fuoridation, as a public health measure, is achieved through the additon of fluoride at water plants, typically to obtain a level of 1 ppm fluoride in drining water. In other areas where the level of fluoride is substantially higher than the recommended level excess fluoride can be removed during processing.
Fluoridated salt has been used in several areas of the world, including parts of Europe and latin America. A recent review of the literature led to the determination that there are no randomized, controlled clinical trials on the use of fluoridated salt to enable conclusions to be dreawn as to its efficacy.
Fluoride supplements can be given to at risk children as drops, lozenges or tablets, with the dose varying with the level of fluoride contained in the domestic water supply and age of the child. The use of fluoride supplements by pregnant women does not result in any benefit for the baby.
During tooth development, the cumulative ingestion of fluoride prior to pre-eruptive enamel maturation results in fluoride ions replacing hydroxyl ions and the formation of fluorapatite crystals instead of hydroxyapatite crystals. The fluorapatite crystals are smaller and stronger than hydroxyapatite crystals and are more resistant to demineralization associated with the dental caries process. Recent reviews have suggested that the effect of fluoride, including that contained in supplements, foods and drinks, is mainly the result of its topical effect.
Topical fluorides are available as in-office fluorides and home-use fluorides. Topical fluorides act intra-orally by:
Providing periodic high doses of fluoride (in office)
Providing low regular doses of fluoride (home-use)
Available in U.S. as:
Acidulated phosphate fluoride (or acidulated sodium sodium fluoride)
Fluoride from glass ionomer cements
Other fluoride-releasing dental materials
Acidulated formulations were first investigated with the goal of increasing fluoride uptake and ion exchange through the use of low pH. These included phosphate to prevent dissolution of dental hard tissues. Other investigators focused on formulations that had the potential to bind the fluoride to the tooth surface or prolong the application for greater fluoride release and availability.
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin. The anti-caries benefit derived from topical fluoride can be attributed primarily to the prevention of demineralization and the promotion of remineralization. Ensuring the ready availability of intra-oral fluoride helps prevent demineralization from occurring and, should it occur, aids remineralization. Topical fluoride is also believed to inhibit caries activity through bacterial inhibition.
Most of the topical effect of fluoride is due to the presence of available fluoride rather than the influence of fluoride uptake during fluoride therapy. As previously mentioned, ingested fluoride also contributes to the topical effect of fluorides. Omitting plaque removal with a professional prophylaxis prior to the use of in-office topical fluorides has been found to still result in the formation of calcium fluoride-like globules at the tooth surface and, in fact, to increase fluoride retention and the efficacy of fluoride therapy. Regular rinsing with fluoride in the presence of plaque has been shown to result in the deposition of alkali-soluble (available) fluoride.
In Office Fluorides
In office fluorides are available as varnishes, gels, foams and rinses. These differ by type off fluoride, concentration, method and length of application.
In the United States, fluoride varnish is available as 5% sodium fluoride, equivalent to 22,600 ppm fluoride. While the FDA has cleared varnish as a device for the relief of hypersensitivity and as a cavity liner, the vast majority of clinical trials, evidence-based studies and the major use worldwide is as an in-office topical fluoride for the prevention of dental caries. In addition, the American Dental Association recommends the use of 5% sodium fluoride varnish for caries prevention for children of all ages (including children under 6 years of age) and for adults. Both tinted and white/clear versions are available in tubes and/or unit doses. Patients tend to prefer the white/clear for esthetic reasons, while dental professionals tend to prefer the tinted for ease of application. Application frequencies of twice or four times per year have been advocated, as well as more frequently than four times per year in some cases of early childhood caries.
Gels and foams are available as acidulated phosphate fluoride and as sodium fluoride. Acidulated phosphate fluoride (APF) gels and foams contain 12,300 ppm fluoride, and neutral sodium fluoride gels contain approximately 9,000 ppm fluoride. These are available as either a four-minute or a one minute application. There is clinical support and evidence for the efficacy of four0-minute gel applications. Foam has the advantage of resulting in a lower dose of applied fluoride compared to gel, reducing the risk of ingestion. The use of in-office fluoride gels and foams is not recommended for children under age 6, who are at greater risk of fluoride ingestion during application and have less ability to spit our excess afterward.
In-office Fluoride Rinses
In-office topical rinses are available as 2% sodium fluoride rinses and dual rinses containing stannous fluoride and acidulated phosphate fluoride. These should not be used in young children, due to the risk of ingestion.
The American Dental Association encourages dental professionals to employ caries risk assessment strategies in their practices. Appropriate preventive dental treatment (including topical fluoride therapy) can be planned after identification of caries risk status. It also is important to consider that risk of developing dental caries exists on a continuum and changes over time as risk factors change. Therefore, caries risk status should be re-evaluated periodically.
Patients can be classified as being at low, moderate or high risk for caries at a given time. Low-risk patients are those who have no factors that may increase their risk of caries and who have had no incipient, cavitated or secondary carious lesions in the prior three years, according to the guidelines in the ADA recommendations on professionally applied fluorides. All other patients are either moderate or high risk.
For moderate- and high-risk patients, the American Dental Association recommendations are for the use of fluoride varnish in children under age 6 and either fluoride varnish or a four-minute gel in patients age 6 and over. The recommended frequency of application for these patients is two to four times per year, depending on risk level. The ADA recommendations do not include the use of foam specifically because there are few clinical trials conducted on foam to demonstrate its efficacy. However, those that were conducted, together with laboratory data, suggest that it may be equivalent to fluoride gel. For low-risk patients, in-office topical fluorides are not recommended, and the use of fluoride dentifrice may suffice. Professional judgment is required for individual patients.
Low Risk Patients
< 6 years of age: Professional Fluoride may be of no benefit
6-18 years of age: Professional fluoride may be of no benefit
18+ years of age: Professional fluoride may be of no benefit
< 6 years of age: Fluoride varnish 2 times per year
6-18 years of age: Fluoride varnish or gel 2 times per year
18+ years of age: Fluoride varnish or gel 2 times per year
< 6 years of age: Fluoride varnish 2-4 times per year
6-18 years of age: Fluoride varnish or gel 2-4 times per year
18+ years of age: Fluoride varnish or gel 2-4 times per year
Suboptimal fluoride exposure
Poor oral hygiene
Familial high caries rate
High bacterial load
High frequency sugar and other carbohydrate consumption
Drug or alcohol abuse
Home-use fluorides include fluoride denitrifies as well as over-the-counter and prescription gels, pastes, and rinses. The majority of over-the-counter dentifrices available in the United States contain 1,000-1,100- ppm fluoride, available as sodium fluoride, sodium monofuorophosphate and stannous fluoride, and have been found to be effective with these formulations.
Use of these in-home dentifrice twice daily provides a regular supply of fluoride that results in the presence of low levels of fluoride intra-orally on the teeth and soft tissues. It is recommended to commence use of a fluoride dentifrice in children at age 2, using only a pea-sized amount twice daily from the age of 2 and until reaching 6 years of age. Children under the age of 6 should always be supervised while brushing.
Prescription home-use 1.1% sodium fluoride, equivalent to 5,000 ppm fluoride, is available as pastes containing a mild abrasive and as gels/liquids containing no abrasive. These can also be used in mouth trays for extended at-home application.
Prescription, 0.2% sodium fluoride, and over-the-counter fluoride, 0.05% sodium fluoride, rinses are available for home-use. Significant caries reductions have been observed with daily rinsing in subjects living in areas with up to 0.3 ppm fluoride in the water.
It is certainly important for infants and children between the ages of 6 months and 16 years to be exposed to fluoride. This is the timeframe during which the primary and permanent teeth come in. However, adults benefit from fluoride too. New research indicates that topical fluoride — from toothpastes, mouth rinses, and fluoride treatments — are as important in fighting tooth decay as in strengthening developing teeth.
In addition, people with certain conditions may be at increased risk of tooth decay and would therefore benefit from additional fluoride treatment. They include people with:
Dry mouth conditions: Dry mouth caused by diseases such as Sjgren’s syndrome, certain medications such as allergy medications, antihistamines, anti-anxiety drugs, and high blood pressure drugs), and head and neck radiation treatment makes an individual more prone to tooth decay. The lack of saliva makes it harder for food particles to be washed away and acids to be neutralized.
Gum disease: Also called gingivitis, gum disease can expose more of the tooth and tooth roots to bacteria increasing the chance of tooth decay.
History of frequent cavities : If an individual has one cavity every year or every other year, they might benefit from additional fluoride.
Presence of crowns and/or bridges or braces : These treatments can put teeth at risk for decay at the point where the crown meets the underlying tooth structure or around the brackets of orthodontic appliances.
Fluoride is the only chemical added to water for the purpose of medical treatment. Fluoride is classified as a drug when used to prevent or mitigate disease, and as such, many feel informed consent should be a standard for fluoride, as it is will all other medications.
Only eight countries in the world have more than 50% of their populations drinking artificially fluoridated water including Australia, Columbia, Ireland, Israel, Malaysia, New Zealand, Singapore and the United States.
Those who oppose the wide use of fluoride site reasons such as the potential for fluoride to lower IQ, cause non-IQ neurotoxic effects, have a negative affect of thyroid function and cause arthritic symptoms, as well as many other controversial affects.
Fluoride is safe and effective when used as directed but can be hazardous at high doses (the “toxic” dosage level varies based on an individual’s weight). For this reason, it’s important for parents to carefully supervise their children’s use of fluoride-containing products and to keep fluoride products out of reach of children, especially children under the age of 6.
In addition, as mentioned earlier, excess fluoride can cause fluorosis usually in children under 6 years. Although tooth staining from fluorosis cannot be removed with normal hygiene, a dentist may be able to lighten or remove these stains with professional-strength abrasives or bleaches.
Keep in mind, however, that it’s very difficult to reach hazardous levels given the low levels of fluoride in home-based fluoride-containing products.
A few useful reminders about fluoride include:
Store fluoride supplements away from young children.
Avoid flavored toothpastes because these tend to encourage toothpaste to be swallowed.
Use only a pea-sized amount of fluoridated toothpaste on a child’s toothbrush.
Be cautious about using fluoridated toothpaste in children under age 6. Children under 6 years of age are more likely to swallow toothpaste instead of spitting it out.
Bottled Water and Fluoride
Even though there’s no scientific studies to suggest that people who drink bottled water are at an increased risk of tooth decay, the American Dental Association (ADA) says that such people could be missing out on the decay-preventing effects of optimally fluoridated water available from their community water source. The ADA adds that most bottled waters do not contain optimal levels of fluoride, which is 0.7 to 1.2 parts per million (this is the amount that is in public water supplies, in the communities that have fluoridated water).
Home Water Treatment Systems and Fluoride
The amount of fluoride in drinking water depends on the type of home water treatment system used. Steam distillation systems remove 100% of fluoride content. Reverse osmosis systems remove between 65% and 95% of the fluoride. On the other hand, water softeners and charcoal/carbon filters generally do not remove fluoride. One exception: some activated carbon filters contain activated alumina that may remove over 80% of the fluoride.
Fluoridation is widely, but not universally, accepted by dental professionals as being useful. Fluoride combats the decay primarily by the formation fluorapatite via remineralization of enamel. Fluoride controls the rate at which cavities develop.
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