Fluoride is the classic active ingredient for cavity prevention. However, excessive intake of fluoride can lead to health problems. And with BioHAP, there is a modern active ingredient without the risks of fluoride.
The idea of using fluoride for cavity prevention was discovered by chance at the beginning of the 20th century.
Curiously, the trigger for the research was dental fluorosis caused by excessively high fluoride concentrations in the local drinking water: the population showed brown spots on their teeth but had little tooth decay. Since around the 1960s, fluoride has been used in toothpaste and other oral care products for cavity prevention.
That is precisely the problem: the right amount of fluoride can protect. However, hitting that target is not always easy, and this leads to negative consequences: Almost one in four children suffers from fluorosis.* Yet with our KAREX toothpastes and gels, there has long been effective cavity protection with BioHAP instead of fluoride.
Overdosing is easy – especially in children up to 6 years of age
Use fluoride-free toothpaste with BioHAP – BioHAP is effective and safe
Minimize the risk of fluorosis – controlling total fluoride intake is key
Fluoride-containing toothpastes must carry a warning label, as there is a risk that children in particular may swallow too much toothpaste and therefore too much fluoride. Fluoridated toothpaste for children up to 6 years of age containing 1,000 ppm fluoride or more should only be applied in a "pea-sized" amount to the toothbrush, and for children under 2 years of age even only in a "rice grain-sized" amount.
However, children (and many parents) are unable to implement this consistently and therefore automatically overdose, even when using toothpaste as the only source of fluoride.
A study showed that the amount of toothpaste used in German bathrooms exceeds the recommended amount by more than five times. △
Children are particularly vulnerable to fluoride overdose due to their low body weight. Many also swallow toothpaste while brushing and can thereby absorb approximately as much fluoride as through fluoride tablets or fluoridated table salt.
Fluorosis: whitish to brownish spots, especially on the front incisors
Lifelong damage: Dental fluorosis persists for life. It is not only an aesthetic concern but also affects tooth structure. Fluorosis can only be removed through dental procedures. Prevention is the best way to avoid dental fluorosis.
Tooth enamel defects or even enamel breakdown: can occur with severe fluoride overdose during tooth development
When parents hear (or read) "fluoride," they quickly think of fluoride tablets — and of course of toothpaste (our KAREX is made with BioHAP instead of fluoride). But there are many other sources of fluoride in everyday life.
Many households use fluoridated salt when cooking and baking — this means fluoride can quickly be overdosed.
Even the Consumer Advice Center recommends: "If you use fluoridated salt, you should avoid additional fluoride supplements (dietary supplements or medications)."♢
Some foods contain notable amounts of fluoride — these include fish, e.g. herring, bloater (0.36 mg/100 g), or sardines, seafood, and black tea.
Fluoride is also found in grains, liver, and meat, as well as in soybeans (0.36 mg/100 g) and walnuts (0.7 mg/100 g).
The highest amounts of fluoride, however, are found in fluoridated table salt (31 mg/100 g) as well as in drinking water and mineral water.
The addition of fluoride to toothpastes is a subject of controversial debate, especially when it comes to products for children under 6 years of age. The main problem: dosage.
Fluoridated toothpaste for children up to 6 years that contains 1,000 ppm fluoride or more should only be applied in a “pea-sized” amount on the toothbrush; for children under 2 years, the amount should be only “rice-grain-sized.”
However, in everyday use, the legally mandated limitation that must be indicated on toothpaste tubes is, on average, exceeded by a factor of five to seven.△
To prevent cavities, babies and toddlers are frequently prescribed fluoride tablets, particularly in areas with low fluoride levels in drinking water.
For healthy bone growth, pediatricians also like to prescribe Vitamin D tablets, often as a combined fluoride supplement.
When using fluoride tablets, dental professional associations as well as pediatricians also recommend brushing with a fluoride-free toothpaste.
BioHAP is "Hydroxyapatite" – the substance our teeth are made of. But BioHAP also stands for effective cavity protection without risk: the alternative for children and everyone who does not want fluoride in their toothpaste.
The hydroxyapatite used in our KAREX oral care products is biomimetic – it originates from the laboratory but works like the chemical compound that also occurs in nature.
Effectively protects against cavities: That BioHAP effectively protects against cavities is clinically proven. Several studies ◐✦ show that toothpaste with BioHAP prevents cavities just as well as fluoride-containing toothpaste.
Repairs tooth enamel: BioHAP can even repair small defects in the tooth enamel and support the reintegration of important minerals (remineralization) into the enamel.
Reduces sensitivity: Hydroxyapatite deposits on teeth and tooth necks, thereby also helping with sensitive teeth, e.g. chalk teeth (MIH)
The use of fluoride in toothpaste is particularly controversial for children under 6 years of age. Children in particular swallow a large portion of the toothpaste.
Due to the intake of additional sources of fluoride (vitamin D supplements with fluoride, fluoridated salt, etc.), the risk of developing fluorosis (white spots on the teeth caused by increased fluoride intake) increases significantly. For example, the German Federal Institute for Risk Assessment points out that if a children’s toothpaste with 500 ppm fluoride is swallowed, just as much fluoride is ingested as, for instance, through fluoridated salt.
According to the new recommendations, the amount of swallowed fluoride can therefore double. The risk of fluorosis is significantly higher with toothpastes that have a higher fluoride content (from 1000 ppm).
KAREX relies on the tooth-related active ingredient Hydroxyapatite (BioHAP) in all products. When swallowed, it is simply dissolved in the stomach. Numerous studies confirm its effectiveness: Hydroxyapatite repairs enamel with every brushing, reduces bacterial adhesion, and thus provides effective protection against cavities.
Our tooth enamel consists almost entirely of Hydroxyapatite. That is why BioHAP (biomimetic Hydroxyapatite) is used as an active ingredient in oral care. The highly concentrated active ingredient also serves as a source of calcium and protects our teeth against bacterial acids. Numerous studies confirm the benefits of Hydroxyapatite in the field of oral care and prevention.
Yes, BioHAP protects just as effectively as fluoride against cavities. BioHAP forms a protective layer on the tooth surface that prevents bacteria from adhering to the tooth and thus helps prevent cavities and gum inflammation. In addition, BioHAP releases calcium during acid attacks, which protects the teeth.
In contrast to many other fluoride-free toothpastes, KAREX uses Hydroxyapatite (BioHAP) as its active ingredient. This is the substance our teeth are made of. BioHAP protects at least as effectively against cavities as fluoride – without the risks of overdosing.
KAREX is “Made in Germany” and is developed and distributed by the Dr. Wolff Group, a fourth-generation family-owned company based in Bielefeld.
You probably already know one of our other strong brands such as Alpecin, ALCINA, Plantur, Linola, Bioniq® or V-san. You can find out more about us at drwolffgroup.com.
Numerous publications confirm the effectiveness of BioHAP in dental care. These include not only laboratory studies (in vitro) but also studies with test specimens under oral cavity conditions (in situ), as well as, in particular, clinical studies on patients (in vivo).
For more information, feel free to read the German short summary or the original study. You can get an overview of the large number of studies on Hydroxyapatite as an active ingredient in dental care by browsing our study database (usable without registration).
Almost half of first-grade children, including you or your child, have already had cavities. Learn more about cavities, fluorosis, and proper dental care for children.
Discover the causes of fluorosis and find out how you can treat it effectively. Protect your teeth and learn what you can do to prevent fluorosis!
Cavities in your child? Find out how you can prevent them and keep your child’s teeth healthy. Discover the best tips now!
Many parents and dentists are facing a new challenge: chalk teeth. Around 30% of 12-year-olds suffer from molar incisor hypomineralization (MIH). But what exactly are chalky teeth? Find out more and protect your child’s teeth!
KAREX is different, because Dr. Wolff is different. And so is our research. We not only sell oral care products with clinically proven efficacy, we also actively ensure that research in dental health continues to progress.
* Meyer-Lueckel, H., Grundmann, E., Stang, A. (2010): Effects of fluoride tablets on caries and fluorosis occurrence among 6- to 9-year olds using fluoridated salt. Community Dent Oral Epidemiol.; 38(4):315-23.
△ Sudradjat, H., Meyer, F., Fandrich, P. et al. (2024): Doses of fluoride toothpaste for children up to 24 months. BDJ Open 10, 7
◐ Deutsche Gesellschaft für Ernährung Ausgewählte Fragen und Antworten zu Fluorid | DGE; accessed on 29 July 2025
✦ Chachra, D., Limeback, H., Willett, T. L., Grynpas, M.D. (2010): The long-term effects of water fluoridation on the human skeleton. J Dent Res.; 89(11):1219-23.
⏀ Helte, E., Donat Vargas, C., Kippler, M., Wolk, A., Michaëlsson, K., Åkesson, A. (2021): Fluoride in drinking water, diet, and urine in relation to bone mineral density and fracture incidence in postmenopausal women. Environ Health Perspect.; 129(4):47005.
❉ Malin, A. J., Lesseur, C., Busgang, S. A., Curtin, P., Wright, R. O., Sanders, A. P. (2019): Fluoride exposure and kidney and liver function among adolescents in the United States: NHANES, 2013-2016. Environ Int.; 132:105012.
✧ Wimalawansa, S. J. (2020): Does fluoride cause the mysterious chronic kidney disease of multifactorial origin? Environ Geochem Health.; 42(9):3035-3057.
❖ Griebel-Thompson, A. K., Sands, S., Chollet-Hinton, L., Christifano, D., Sullivan, D.K., Hull, H., Carlson, S. E. (2023): A scoping review of iodine and fluoride in pregnancy in relation to maternal thyroid function and offspring neurodevelopment. Adv Nutr.; 14(2):317-338.
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▲ Limeback, H., Enax, J. & Meyer, F. (2021): Biomimetic hydroxyapatite and caries prevention: a systematic review and meta-analysis. Can J Dent Hyg.; 55(3):148–159.
◓ Amaechi, B.T., AbdulAzees, P.A., Okoye, L.O. et al. (2020) Comparison of hydroxyapatite and fluoride oral care gels for remineralization of initial caries: a pH-cycling study. BDJ Open 6, 98-159
