Fluoride in dentistry: brief updated guidelines for caries prevention

Pages: 97-109

Konstantina Kritikou (1), Arina Vinereanu (2), Aneta Munteanu (2)

(1) PhD student, Carol Davila University, Bucharest <br>(2) Carol Davila University, Bucharest


Fluoride has raised many controversies over time. At present, the beneficial effects of fluoride in caries prevention and remineralization are scientifically supported, therefore indisputable.

This article aims to bring to the attention of dental practitioners up-to-date information on the use of fluoride products, both in the dental office and at home. Fluoride can be administered topically and/or systemically. As topical fluoridation has proven more effective even in high-risk children, current recommendations of the European Academy of Paediatric Dentistry (EAPD) limit indications for general fluoridation. Topical fluoridation can be performed at home and in-office. Brushing twice a day with a toothpaste with 1000 ppm fluoride or more is recommended since the eruption of the first tooth and can substantially contribute, along with healthy dietary habits, to primary prevention of tooth decay. Since home-use products have a maximum concentration of 1500 ppm F, overdose risk is minimal. Fluoride gels and solutions may also be used at home according to dental practitioner’s recommendations and under parental supervision. Professional fluoridation with varnishes and gels offers more protection for patients with high and moderate caries risk.

Conclusions. Fluoride products are safe and very effective in preventing and arresting tooth decay. Dentists need to provide accurate and up-to-date information to paediatricians and general practitioners (GPs), as well as to patients, as to efficiently limit the effects that “fake news” in the online environment still have upon general population.

Keywords: fluoridation, caries prevention, children

Introduction. Advantages of fluoride use, methods of administration, mechanisms of action

Tooth decay is a multifactorial infectious process; carbohydrates metabolism by cariogenic bacteria, especially in the presence of retentive dental surfaces, generates acidic products which demineralize the surface of the enamel. This incipient carious lesion is reversible when etiological factors are readily removed and remineralization mechanisms are initiated and favoured by fluoride’s action [1,2]. Prevalence and severity of carious lesions can be significantly reduced in all age groups, including children, adolescents, and people with special health care needs, by using fluoride products which have numerous protective mechanisms [3].

Low levels of fluoride in bacterial plaque and saliva inhibit enamel demineralization and promote remineralization. Fluoride can also inhibit the development of carious lesions by modifying the metabolism of cariogenic bacteria [4]. High fluoride concentrations form a protective layer of calcium fluoride on the tooth surface,from where fluoride is released as pH decreases due to acid production. The resulting fluoride ions and can act by remineralizing the enamel or may interfere with bacterial metabolism [5]. Depending on the concentration of fluoride products, a bacteriostatic or even bactericidal action can be expected.

Fluoride can be administered either systemically or by topic applications. Fluoridated drinking water as well as systemically administered fluoride supplements may also have a local effect on erupted teeth by increasing the concentration of fluoride in saliva and crevicular fluid. In addition, high levels of fluoride in blood plasma can have a local effect on the completely mineralized surfaces of teeth that have not yet erupted. Similarly, topically applied fluoride products may have a general effect if swallowed [6].

Systemic fluoridation with supplements such as tablets or droplets currently has very limited recommendations. Potential benefits of systemic fluoridation are moderate and may be seen in permanent dentition. From a scientific point of view, there is insufficient evidence regarding general administration of fluoride and its effect on primary dentition. Systemic administration of fluoride during pregnancy also has insufficiently demonstrated effects. Therefore, administration of fluoride supplements should be restricted to children with high risk of caries, aged 6 months to 16 years and living in areas with low levels of fluoridated drinking water [7].

The main sources of fluoride for systemic administration are water, fluoridated beverages and some foods. American Dental Association (ADA) suggests that a concentration of 0.7 ppm fluoride (0.7 mgF/l) in drinking water is ideal. In Romania, only the Globu Craiovei – Caraș Severin area and a few localities in Constanța County contain fluoride-rich drinking water [8]. Given that, risk of overdose through topical applications of fluoride is extremely low in Romania.

The European Academy of Paediatric Dentistry (EAPD) recommends local administration of fluoride as a first-line measure to limit carious activity, with systemic fluoridation having a secondary role. Local fluoridation can contribute significantly to primary prevention of dental caries and can also help in secondary prevention by arresting early lesions,including in patients with orthodontic appliances and people with special oral health care needs, both these categories being considered at high risk of developing tooth decay [9,10].

Topical fluoride products (toothpastes, gels, varnishes) can be applied at home or in the dental office [7]. The main difference between professional and home-use products is fluoride concentration, professional products having a much higher amount of fluoride. To avoid risk of overdose or toxicity, patients should not use products for professional use at home.

Fluoride prophylaxis at home

Fluoridation at home can be done with toothpastes, mouthwashes and gels. The EAPD recommendations suggest the use of fluoride toothpaste since the eruption of the first tooth around the age of 6 months (Table 1). Toothpastes with fluoride concentration of 1000 ppm are recommended for children under 6 years of age; however, in the event of an increased risk of decay, the paediatric dentist may recommend a toothpaste with higher concentration (1450 ppm F) for this age group. With the eruption of the first permanent teeth – from the age of 6 – toothpastes with a fluoride concentration of 1450 ppm should be used for additional protection of immature dental tissues.

Not only the fluoride concentration in the toothpaste must be according to dental practitioner’s recommendations, but also the amount of toothpaste used for each brushing. For small children, aged 6 months to 2 years, this amount should be minimal, like a grain of rice, while between 2 and 6 years it increases to the size of a pea. For children over the age of 6 years as well as for adults the amount of toothpaste can reach the length of the toothbrush. However, regardless of the concentration of fluoride in the toothpaste and the amount used, toothbrushing should be performed twice a day, in the morning before breakfast and in the evening after the last meal [7]. In order to benefit even more from the protective effect of fluoride it is recommended to avoid rinsing with plenty of water after brushing. This recommendation also applies for adults. Excess toothpaste is spit out and the remaining toothpaste (from cheeks and tongue) can be removed with a gauze.

Table 1. EAPD recommendations regarding the use of fluoride toothpaste[7]

(*) higher concentrations may be recommended for this age group depending on caries risk

Patients at high caries risk, including those wearing orthodontic appliances and people with special health care needs, can use toothpaste with fluoride concentration up to 5000 ppm. Such toothpastes can be purchased upon prescription and are only available in certain countries (currently not in Romania). However, the effectiveness of these toothpastes is not fully elucidated [7,11].

Fluoride mouthwash can complete oral hygiene and is recommended for children over 6 years old to avoid the risk of swallowing the product. For maximum efficiency, mouthwash is to be used at a different time from that of toothbrushing. Rinsing with mouthwash should last 1 minute and children should always be supervised by parents. The use of mouthwash does not replace brushing with fluoride toothpaste, as it does not mechanically remove dental plaque. It is recommended to use mouthwashes with a low concentration of fluoride in order to avoid risk of overdose. The highest fluoride concentrations in mouthwashes are 0.05% NaF (225 ppm F) for daily use and 0.2% NaF (900 ppm F) for weekly use.

Fluoridation at home can also be done with fluoride-containing gels (NaF 1.1%, equivalent to 5000 ppm F; SnF 0.15%, equivalent to 1000 ppm F). Gels are to be used after evening brushing; they can be applied either with the toothbrush or in special devices. They are meant for daily use, especially in people at high caries risk (patients undergoing orthodontic treatment, patients with special needs), but only upon dentist’s recommendation. However, caution is required in recommending this type of products for home use due to risk of ingestion [2].

Fluoride prophylaxis in the dental office

Professional fluoridation has many advantages, including easy and quick application, increased efficiency and low cost. In addition, the products usually have a pleasant taste and are well tolerated by patients. Although professionally applied products contain high amounts of fluoride, risk of fluorosis is low through controlled and well-monitored applications.

Patients with high caries-risk, poor oral hygiene or who cannot perform proper brushing, patients with various motor disabilities, those with active caries and hard tissue defects that require an improvement of enamel resistance to acid attack, patients with various general pathologies or undergoing radiotherapy (which causes xerostomia by decreasing salivary secretion) and those whose medication has a high sugar content will benefit from professional fluoridation.

Fluoride products for professional application can be gels, varnishes, solutions or foams, the first two being most commonly used. Regardless of the type of product, fluoridation is usually performed after professional dental hygiene. Fluoride gels can reach concentrations of 9050 ppm (2% NaF) and even 12,300 ppm (1.23% APF). They are suitable for children over 6 years of age and are applied in special trays for about 4 minutes.

Fluoride varnishes are useful for children under 6 years and in generally for people with a lower degree of cooperation. The work technique is very fast and does not require perfect drying and isolation of teeth from saliva. Varnishes contain the highest amount of fluoride available for professional application (5% NaF, 22,600ppm F). Once applied to the tooth and in contact with saliva, the varnish forms a protective layer from which fluoride is slowly released and can prevent decay even in deciduous teeth. Various randomized studies and meta-analyses have shown a 28-70% efficiency of fluoride varnishes in inhibiting caries development in both dentitions.

EAPD recommends the application of fluoride gels or varnishes based upon caries risk and patient’s age (Table 2). Thus, in patients under 6 years of age, professional fluoridation with varnishes is indicated, while patients over 6 years old can benefit from fluoridations with either varnishes or gels, depending on their general medical history and degree of cooperation. In general, in patients with moderate caries risk, fluoridation is indicated twice a year, whilst in those at high risk it should be repeated every 3 to 6 months, depending on the practitioner’s recommendations and the coexistence of factors that favour dental caries [2].

Table 2. EAPD recommendations on topical application of fluoride gels and varnishes[2]

Foam products, such as APF 1.23% (12,300 ppm F), may be an alternative to fluoride gels as they have similar use. Their advantage over gels is the smaller amount of product needed for fluoridation. Various studies suggest that fluoride foams appear to be more effective in permanent dentition [2]. Fluoride rinses can also be used in the dental office (APF/SnF 1500-3000 ppm F), but their recommendation is limited due to the existence of more effective alternatives (fluoride gels / varnishes). They can also be easily swallowed with high risk of toxicity and their taste is sometimes metallic which makes them less tolerable for patients. Regardless of the type of product used, after professional fluoridation the patient is advised to avoid any food or liquids intake for 30 minutes [2].

Fluoride excess. Risks and consequences

Chronic exposure to significant fluoride concentrations during tooth formation and mineralization can cause fluorosis. The risk is significantly increased in the first 2 years of life and often enamel defects may appear on the surface of the upper incisors. Changes in the appearance of dental surface depend on the length of the exposure. Defects can vary from small imperceptible whitish marks or lines to larger opaque, yellowish or brown spots or porous surfaces; in severe cases crown fractures may occur. However, the risk of developing fluorosis due to professional fluoridation is low [12]. Occurrence of fluorosis can be linked to the administration of fluoride supplements, especially during the first 6 years of life [13], to which unintentional ingestion of tooth paste may add [12].

Acute exposure to a large amount of fluoride may lead to neurotoxic effects and even death in isolated cases. The toxic dose of fluoride regardless of patient’s age is 5 mg/kg, while lethal doses differ: 16 mg / kg body weight for children vs 32 mg/kg body weight for adults [14]. To avoid these risks, young children (under 6 years) should not be left unattended during toothbrushing as they can swallow large amounts of toothpaste. All fluoride products should be stored in places where children do not have access. Fluoride products should be applied in observance of dentist’s instructions, respecting the recommended amount and concentration in accordance with age and caries risk.

Fluoride in dental materials

Fluoride is also the main component in certain restoration materials, such as glass ionomer cements (GIC) from which it is gradually released, exerting an anti-caries effect over time. This type of material is also available in encapsulated form, which makes the workflow much easier and faster, especially when dealing with paediatric patients. Other advantages of GICs are given by their capacity to set in moist environment, in conditions of imperfect isolation, and to behave similarly to dental tissues. They can also be used as intermediate restorative materials (IRM) or in restorative atraumatic technique (ART), as they induce remineralization of the remaining dentine, arresting the evolution of decay and preventing secondary caries.


Daily brushing with fluoride toothpaste adapted to the patient’s age, associated with professional fluoride applications and in combination with other methods of caries prevention (fissure sealing, limited carbohydrate consumption and use of slow-release fluoride restorative materials) are measures that can significantly reduce the risk of developing dental caries in all categories of patients, including children with special needs.

It is the responsibility of the paediatric dentist to be informed correctly from scientifically verified sources and to spread the information to patients in an adequate and personalized way, thus increasing the chances of effective caries prevention. Efficient communication between pedodontists on one hand and paediatricians and GPs (who get to see the babies before the dentist does) on the other hand, could help a lot in the same respect.

Note. More detailed and scientific evidence information regarding the indications and use of fluoride can be found in the book “Fluorul-Actualizări și recomandări de profilaxie”, a useful tool for Romanian dentists, as well as for physicians and pediatricians. Available online, downloadable free of charge, at: https://elmexpro.eu/carte-fluor

Contents in Romanian.

Conflict of interests: None


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