Topical Fluorides

Feb. 1, 1998
Various factors influence the decision to prescribe topical fluoride applications to children. The patient`s age, water fluoridation in a community, and the prevalence of caries need to be considered.

Various factors influence the decision to prescribe topical fluoride applications to children. The patient`s age, water fluoridation in a community, and the prevalence of caries need to be considered.

Mary D. Cooper, RDH, MS, and

Connie Myers Kracher, CDA

The major influence in caries prevention has been fluorides. Multiple sources - including water fluoridation, professionally applied topical fluorides, over-the-counter rinses, prescription fluorides, fluoridated tooth pastes, as well as fluoride in processed foods and drinks - have contributed to the reduction in caries.

By current convention, many dentists and dental hygienists routinely are administering professional topical fluoride treatments to patients at their preventive maintenance appointments. However, is this routine procedure necessary for every patient? Although concentrated topical fluoride treatments usually are intended for annual or semiannual prophylaxis visits, a decline in caries prevalence now is bringing into question the continuing need for such treatments in individuals who are caries-free. The decision to use a professionally applied topical fluoride should be based on scientific evidence as well as practical consideration.

Some researchers note current recommendations regarding the application of professional topical fluoride gels. The decision to apply a professional fluoride treatment should be suggested on an individual basis with determining factors based on the level of fluoride in the drinking water, the patient`s age and caries activity level - regardless of living in a fluoridated/nonfluoridated community - and the exposure time of the fluoride treatment.

Since current practice within many dental offices is to deliver a topical fluoride system to every young patient, the dental profession is faced with an ethical quandary when dealing with this issue. If a patient does not show evidence of active caries, should the patient be given a professional fluoride treatment at the prophylaxis appointment? With exposure to so many outside fluoride sources, the patient may be receiving adequate amounts of fluoride - enough to maintain a caries-free condition - without routinely scheduled professional fluoride applications. These frequent exposures to low concentrations of fluoride, as received from rinses and toothpastes, are more effective in the prevention of decay than infrequent exposures to high concentrations of fluoride, as received from professional fluoride treatments.

Recommendations to use topical fluoride applications on the young patient should be determined by whether or not the child - with developing dentition - drinks fluoridated water. Research shows that children living in fluoridated communities are showing an increase in the incidence of mild fluorosis. The reasons may be varied as to why children are developing this condition. However, the accidental ingestion of topical fluorides, such as office applications and toothpastes, may be a contributing factor.

The most popular operator-applied professional fluoride method is by disposable mouth trays using a 1.23 percent acidulated (APF) gel. This procedure offers a method that is convenient to use and is tolerated well by patients. However, a topical application of 1.23 percent APF gel has resulted in fluoride ingestion of between 14 and 31mg. In addition, a study with preschool children showed that approximately 40 percent of the dentifrice used during a toothbrushing procedure was ingested. From these concerns, some researchers have suggested using a professional fluoride application at a decreased exposure time to minimize excess exposure to high-concentration levels of fluoride.

Introduction of one-minute gels

Many "one-minute" topical fluoride gels have been introduced in recent years. Since a reduction of exposure time can reduce the incidence of ingestion, is it still as effective as a four-minute application time on caries-like lesion formation in enamel?

The introduction of the Oral-B APF Minute Gel in 1985 offered practitioners an opportunity to administer fluoride that could save chair time without sacrificing the efficacy of its use. Studies conducted in 1987 and 1988 by S.H.Y. Wei proved that fluoride uptake in enamel is time-dependent due to a diffusion-controlled process and that it should be left on the teeth for the four minutes as previously was suggested. But is the four-minute application necessary for every patient?

Garcia-Godoy, et al, evaluated the effect of acidulated phosphate fluoride (APF) application time (one to four minutes), in vitro, on caries-like lesion formation in enamel. The APF gel used for this study was Oral-B APF Minute Gel. The difference in the uptake of fluoride in enamel between a one-minute application of APF gel and a four-minute application was slight - the difference in mean lesion depth between the two treatment groups was slightly over 5 percent. Past studies have shown that the majority of fluoride uptake into enamel from a 1.23 percent APF gel occurs during the first minute of treatment with a gradual increase in fluoride uptake during the remaining three minutes. Recent studies with Oral-B APF Minute Gel have confirmed these previous findings. Fluoride uptake for a one-minute application was almost 70 percent of that of the four-minute application time.

According to Garcia-Godoy, et al, the acceptance and implementation of a one-minute APF application time has merit and provides several advantages over the four-minute application time. This reduction in application time would lessen the potential for acute fluoride ingestion with associated gastrointestinal upset. This decreased treatment time also may reduce the likelihood of adverse effects of etching, which may occur with APF exposure to esthetic dental materials such as porcelain and ceramic surfaces. Patient tolerance and compliance may improve, especially with the young dental patient. In addition, this reduction in application time would result in chair-time savings of one hour for every 20 fluoride treatments.

The application of professional fluoride gels for one minute may be considered for use in private practice since it provides the benefits of caries reduction with less potential ingestion by the patient. Upon examining current information on this topic, practitioners and dental hygienists need to determine if professional topical fluoride applications are appropriate for all their patients. If so, they also need to further determine the frequency of delivery as well as the amount of exposure time.

In 1988, Wei examined whether a foam-based APF agent (developed in 1988) was as effective as APF gel. It was found that the foam-based agent is lighter than gels and will fill a topical fluoride tray with much less weight and, hence, the total amount of fluoride ingested could, potentially, be decreased. Wei`s results indicated that the foam was as effective as gel in the fluoride uptake in enamel. However, since the foam-based APF agent is much lighter than the conventional gel, and only a small amount of the agent is needed for a topical application, it is cost-effective and more acceptable by the patient. The amount of conventional gel needed to treat the mouth is about four grams while foam-based APF requires less than one gram to fill a disposable upper and lower gel tray.

Garcia-Godoy, et al, recommend that patients with active and rampant caries, topical fluoride application should be done more frequently - on a quarterly basis - regardless of whether the child resides in an optimally fluoridated community or not.

The child with active caries requires professionally applied fluoride applications twice a year. Moreover, the child with rampant caries should not only receive topical fluoride treatment on a quarterly basis, but may require a home fluoride-treatment program as well. Topical fluoride treatment for the caries-free child should be done twice a year up to age 16, if residing in a fluoride-deficient community. No topical treatment is necessary for the child residing in an optimally fluoridated community.

Frequency and exposure time

Whichever fluoride system is used for topical fluoride applications, Stookey and Beiswanger indicate that the teeth should be exposed to the fluoride for four minutes for maximal cariostatic benefits with caries-active patients. This treatment time has consistently been recommended for both sodium and acidulated phosphate fluoride. Although reduced exposure periods of 30 to 60 seconds may be appropriate as a fluoride maintenance or preventive measure in patients with very little caries activity, the use of the longer four-minute application should be required for patients with existing caries activity.

Stookey and Beiswanger believe that the protocol in many offices is to use a specific topical fluoride system and treatment regimen for every patient. It should be emphasized, however, that the specific needs of the patient should be ascertained initially and a specific treatment program developed to fulfill those needs.

For example, the use of a series of four or more topical applications should be considered for a patient with a severe caries problem. Likewise, a reduced topical application time of 30 seconds as opposed to four minutes may be adequate to maintain a patient with little or no current caries activity. There is little fluoride deposition lasting more than 24 hours when fluoride is applied to sound, fully maturated enamel. Therefore, there appears to be no preventive benefits from the application of a fluoride to adult patients with sound enamel.

Age differential

The 1995 JADA special supplement on caries diagnoses and risk assessment indicates that there is evidence that the incidence of mild dental fluorosis is increasing in children who reside in fluoridated areas. Although the reasons for this are varied, the risk for developing mild fluorosis can increase with unintentional ingestion of topical fluoride products, including toothpastes, rinses and gels. Therefore, professionally applied topical fluoride treatments and home fluoride-rinse products are not recommended generally for children under age six and adolescents at low risk for developing caries who live in fluoridated communities and use a fluoridated toothpaste.

Indications for patients with moderate or high caries risk, due to smooth- or root-surface caries activity, should have professional applied sodium or acidulated phosphate fluoride applications. Since fluoride is most effective on smooth- and root-surface caries, patients with orthodontic appliances, individuals undergoing head and neck irradiation and patients with a decreased salivary flow - usually due to systemic conditions or side effects from medications - will greatly benefit from these fluoride treatments. However, the use of fluorides is not as effective on pit and fissure surfaces. Therefore, sealants may be indicated for caries prevention. Again, professional fluoride applications are not recommended for individuals with caries-free status who reside in optimally fluoridated areas.

Although Garcia-Godoy, et al, research states that most fluoride uptake in enamel is within the first minute, a four-minute fluoride application by tray with an ADA-accepted professional topical product (gel or foam) still is recommended for patients with existing or potential caries activity. Note that a professional prophylaxis is not needed prior to application of professional topical fluoride products because fluoride uptake and caries inhibition are not improved by a prophylaxis. Also, use of a fluoride prophylaxis paste does not indicate a professionally applied fluoride application.

Dental offices should establish a protocol regarding professional topical fluoride applications to patients. As stated earlier, if the patient lives in an optimally fluoridated community and is caries-free, no professional fluoride application is necessary. The practitioner may consider not applying professional topical fluoride treatments to children under the age of six and adolescents who are at low risk in developing decay if they live in an optimally fluoridated community and use fluoridated toothpastes. However, if the patient lives in an optimally fluoridated area and has active caries (one or more lesions), it is suggested that the topically applied fluorides be given twice yearly. Likewise, those individuals living in an optimally fluoridated area with rampant caries should receive a professional topical fluoride application four times a year.

Recommendations for individuals living in a deficient fluoridated community (greater than 0.7 ppm) will be slightly different. If the patient is caries-free, a topical fluoride application is suggested twice a year. Recommendations for patients who have a caries status that is active or rampant will be the same as for those living in an optimally fluoridated area (twice yearly and four times per year, respectively).

Therefore, recommendations concerning professional fluoride applications should be determined according to the patient?s caries prevalence, age of the patient living in a fluoridated/nonfluoridated area, the exposure time of the fluoride treatment and the number of fluoride applications.

Mary D. Cooper, RDH, MS, is associate professor of dental hygiene at Indiana University-Purdue University at Fort Wayne, Ind. Connie Myers Kracher, CDA, BSEd is a graduate dental student in the preventive dentistry program at Indiana University School of Dentistry, as well as assistant professor of dental education at Indiana University-Purdue University Fort Wayne.


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