Caries protection through the use of fluorides, including amine fluorides, is of fundamental importance in individual dental prophylaxis. Fluorides are salts of hydrofluoric acid (HF) and are widely distributed in nature. They are found in soil and in all water, with particularly high concentrations in seas and volcanic soils. Fluoride is naturally present in tooth enamel as a trace element and is required in the enamel formation phase during tooth development. The fluoride concentration increases in the enamel layer towards the tooth surface. The higher the fluoride concentration in the superficial enamel layer, the more resistant the enamel is to the effects of acids from food or bacterial metabolism. Acids lead to demineralization (softening) of the enamel and eventually to cavitation (formation of a hole). Accordingly, various fluorides are used for caries prophylaxis, which easily release fluoride ions in the aqueous oral environment, which can be incorporated into the enamel surface by ion exchange and cause an increase in hardness there. An increase in fluoride concentration occurs not only in the enamel, but also in the microbial plaque (the dental plaque). Fluorides interfere with bacterial metabolism by inhibiting enzymes required for the metabolism of sugar molecules. Organic acids are a decomposition product of the metabolism. If bacterial metabolism is disturbed, the enamel is less exposed to acid action. Chemically, a distinction can be made between inorganic fluoride compounds:
- Sodium monofluorophosphate
- Sodium fluoride
- Tin fluoride
and the substance group of organic amine fluorides, such as.
- Olaflur
- Dectaflur
- Hetaflur
All of these fluoride compounds used to protect against caries work:
- Caries inhibitory by disrupting the plaque metabolism.
- Promoting the remineralization of tooth enamel (re-deposition of fluoride and other minerals in the enamel surface), thereby
- Hardness-increasing by
- Lowering the acid solubility of the melt.
- As a fluoride depot by forming a sparingly soluble calcium fluoride covering layer on the tooth surface. From this top layer fluoride goes into solution when exposed to acid, which is available for remineralization
Amino fluorides are hydrofluorides of amines. The molecules have both hydrophobic (water-repellent) and hydrophilic (water-attracting) components and thus have a surface wetting effect. This surfactant effect (surfactants are substances that reduce the surface tension of a liquid or act as solubilizers) makes them fundamentally different from inorganic fluoride compounds:
- On the one hand, surfactants disperse plaque (dental plaque) and thus support the cleaning action of toothpastes. Amino fluoride-containing toothpastes do not require any further surfactant addition.
- On the other hand, the amine fluorides due to their surfactant effect easily attach to the cleaned tooth surface and thus form a fluoride-containing top layer.
- In vitro (under laboratory conditions), amine fluorides have been shown to inhibit bacterial attachment to the pellicle (enamel cuticle) somewhat better than other fluoride compounds. However, this attachment is essential for the maturation of a plaque layer. Thus, amine fluorides have a slight plaque-reducing effect.
- Amino fluorides in solution have a lower pH than inorganically bound fluorides, i.e. the solution is slightly acidic. What at first glance appears to be a disadvantage – after all, acids attack tooth enamel – is actually an advantage, because fluoride incorporation is facilitated into the slightly demineralized (decalcified, softened) enamel surface. For this reason, toothpastes with inorganic fluorides are also usually slightly acidic.
- Amino fluorides penetrate the bacterial cell membrane more easily than inorganic fluorides and thus lead more quickly to an inhibition of bacterial metabolism than inorganic fluorides.
Indications (areas of application)
Amino fluorides are used for caries prophylaxis (caries protection, prevention of tooth decay):
- In daily basic prophylaxis in the form of toothpastes in different dosages for children under six years or older children and adults.
- For extended home prophylaxis in case of increased caries risk in the form of mouth rinses or gel concentrates.
- In the context of individual prophylaxis in the dental practice in the form of concentrated touch-ups, gels and varnishes.
Contraindications
- Fluoride history:The appropriate use of fluorides for caries protection in an age-dependent dosage between 0.25 mg and 1 mg per day is now scientifically considered effective and absolutely safe. However, like any active ingredient, fluoride can be harmful if overdosed. Therefore, the recommendation of fluoride-containing preparations should first be preceded by the detailed fluoride anamnesis, which must include the fluoride content of drinking water and mineral waters consumed regularly, as well as dietary habits (fluoridated table salt, sea fish, diets, etc.).
- Swallowing reflex:For children who are not yet able to spit out the toothpaste after brushing, only brush with a small pea-sized amount of low-dose fluoride-containing toothpaste for children (500 ppm, 500 parts per million) to avoid any overdose. From school age, when the swallowing reflex is controlled, the switch to adult toothpaste with 1,000-1,500 ppm fluoride can be made.In patients who do not have control over the swallowing reflex and in children under eight years of age, fluoride should not be applied with the help of ready-made trays (gel carriers), because they hold a large amount of gel and thus fluoride, and the patient must be able to continuously spit out excess material and saliva during the approximately four-minute exposure time.
- Chronic overdose:If the fluoride history is consistent, overdose can be ruled out. However, if multiple systemic sources of fluoride are combined with local sources, chronic overdose may occur.The main source of permanently elevated fluoride intake is drinking water. In areas with more than 1 ppm (more than 1 mg/l) fluoride content in natural drinking water, dental fluorosis must be expected if the increased dosage occurs in the first eight years of life. In this case, the ameloblasts are disturbed in the phase of enamel formation, resulting in chalky mottled enamel with loss of hardness. About one percent of the European population is affected by dental fluorosis.After a lifelong exposure to drinking water above 8 ppm (above 8 mg/l), older people show compacted bone structures. Above 20 ppm, skeletal fluorosis can develop: Fluorides are deposited in the bones and cause changes there. Drinking water with such high fluoride concentrations occurs, for example, in India and South Africa.
- Acute toxicity:The lower toxic limit is 5 mg fluoride per kg body weight (Whitford 1992). Acute toxic side effects of fluorides manifest as nausea (nausea), vomiting, gastric distress, and diarrhea, among others. They are directly dependent on their dosage. To avoid household accidents, toothpastes for adults are often offered in a tube size of 75 ml. A child of four years and 20 kg body weight, if he were to eat the entire contents of the tube, would reach his lower toxicity limit.
- Hypersensitivity reactions:The preparations must not be used in case of existing hypersensitivity to amine fluorides or other ingredients of the preparations.