In-House Research – in Our Own Laboratories at the Main Location in Bielefeld
Collaborative Research – with Independent Institutes, University Clinics, and Dental Practices
Support of Research – on a Small and Large Scale, Nationally and Internationally
Recognized Research Results – KAREX is the first fluoride-free toothpaste with Hydroxyapatite to be approved as an anti-cavity toothpaste by the health authorities in Canada.
In Vitro Study Shows: HAP Remineralizes Dentin and Tooth Enamel (2011) As early as 2011, we were able to demonstrate with the Charité Berlin that HAP remineralizes dentin and tooth enamel better than fluoride. In this in vitro study, the effects of Hydroxyapatite toothpastes on the remineralization of bovine enamel and dentin subsurface lesions were examined.
The results showed that toothpastes with Hydroxyapatite had a higher remineralization effect compared to amine fluoride toothpastes, and comparable trends were observed for tooth enamel.
Read study details:
BioHAP Deposits on the Tooth Surface
Together with the Max Planck Institute, we were able to show that BioHAP deposits on the tooth surface and forms a protective layer that makes it more difficult for bacteria and acids to attack the natural tooth enamel.
The study was conducted in vitro: enamel slabs from bovine teeth were immersed in aqueous solutions of 1, 5, and 10% concentrations of Hydroxyapatite particles. The degree of coverage was then measured and quantified using a scanning electron microscope: after just a single immersion, the samples were clearly visibly covered. With a 10% Hydroxyapatite dispersion, more than one third of the surface was covered with the protective layer after a short period of time.
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BioHAP Can Whiten Teeth After a Single Application
Together with the Fraunhofer Institute, we explored the question of whether BioHAP can whiten teeth after just a single application.
For this purpose, a gel containing BioHAP was applied to teeth in vitro. A phosphate-containing "whitening" mouthwash served as the comparison group, and water as the negative control. Following the application carried out according to the manufacturer's instructions, the teeth were rinsed, dried, and examined by camera for changes in color and brightness.
The results showed that the BioHAP group demonstrated a significant whitening effect compared to before and also compared to the other two groups. BioHAP is gentle on the tooth, even deposits as a protective layer, and thus whitens the teeth.
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In Vivo Study: Gel with HAP Functions as a Calcium Source
We conducted this study with the Braunschweig Public Health Office in Kebon Padangan on Bali, Indonesia. 34 children had HAP gel applied by an experienced dentist 3 times daily for 3 days. Dental plaque was collected at the start of the study and after the study. The calcium and phosphorus values of the plaque samples were analyzed using energy-dispersive X-ray spectroscopy.
Within the limits of the study, the three-day application of the oral HAP gel in children increased the median values of calcium and phosphorus in the plaque. A positive influence of HAP on the remineralization/demineralization process is very likely.
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✸ Institut der Deutschen Zahnärzte: Sechste Deutsche Mundgesundheitsstudie (DMS 6) 2025, abgerufen am 23.09.2025
⌘ Amaechi, B. T., AbdulAzees, P. A., Alshareif, D. O., Shehata, M. A., et al (2019): Comparative efficacy of a hydroxyapatite and a fluoride toothpaste for prevention and remineralization of dental caries in children. BDJ Open 5, 18
◓ 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
ᛞ Meyer, F., Enax, J., Simader, B. (2019) Können wir dank Mundspülungen auf das Zähneputzen verzichten? Dental Tribune 6, 18-19
ᒥ Paszynska, E. et al. (2021): Impact of a toothpaste with microcrystalline hydroxyapatite on the occurrence of early childhood caries: a 1-year randomized clinical trial. Scientific reports 11, 2650
▲ 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.
ᔐ O´Hagan-Wong, K, Enax, J., Meyer, F., Ganss, B. (2021): The use of hydroxyapatite toothpaste to prevent dental caries. Odontology Volume 110, pages 223–230
△ Sudradjat, H., Meyer, F., Fandrich, P. et al. (2024): Doses of fluoride toothpaste for children up to 24 months. BDJ Open 10, 7
KAREX is different, because Dr. Wolff is different. And so is our research. We don't just sell dental care products with study-proven efficacy — we also actively ensure that research in dental health continues to advance. Our focus is on the active ingredient Hydroxyapatite.
For years, cavities have been on the decline in Germany. Dedicated dentists are actively involved in prophylaxis programs, patient education, and the provision of professional dental cleanings.
Nevertheless, 99% of adults and already approx. 50% of children with baby teeth have had cavities at some point (6th German Oral Health Study 2025). ✸ Conventional dental care products are reaching their limits. We have played a significant role in popularizing Hydroxyapatite as "BioHAP" in modern dental care.
But we are not stopping there. Further research and innovative active ingredients are necessary to consistently curb cavities.
Since the founding of Dr. Wolff more than 100 years ago, research has been of central importance to us. Innovations for dental care are developed "Made in Germany" at our company in Bielefeld and in collaboration with recognized dental professionals and scientists around the world.
The use of Hydroxyapatite is far more widespread than just in Germany. Hydroxyapatite has been used in other countries such as Japan for decades. This is why there are many exciting opportunities worldwide to collaborate with scientists — opportunities we gratefully embrace. Here is a selection:
We have set ourselves a clear goal: for everyone to learn about Hydroxyapatite and its benefits in dental care.
To this end, we regularly conduct research and publish in renowned scientific journals, and we present ourselves at leading trade fairs in the dental industry, e.g., at international conferences of the IADR (International Association for Dental Research) as well as at the International Dental Show in Cologne or the IDEM in Singapore.
The Hydroxyapatite used in our KAREX dental care products is biomimetic — it is derived from the laboratory, but works like the chemical compound that also occurs in nature.
The Hydroxyapatite used in our KAREX dental care products is biomimetic, meaning this active ingredient is similar in its structure and composition to the natural crystallites of our tooth enamel.
In 2021, our researchers published an "Atlas of the Fine Structure of Our Teeth," which illustrates the detailed structure of teeth using numerous scanning electron microscope (SEM) images.
The illustrated volume includes chapters with SEM images of enamel and dentin from permanent teeth as well as baby teeth, including the effects of cavities and erosion.
The high magnification of the images makes it possible to even visualize individual Hydroxyapatite crystallites of the tooth enamel.
Numerous scientific publications confirm the effect of Hydroxyapatite in dental care. Here, those with a scientific interest can get an overview and find further information on current research findings.
As part of a Canadian-German collaboration in 2021 at the University of Toronto, we were able to demonstrate with Dr. Kelsey O'Hagan-Wong and Prof. Hardy Limeback that toothpastes with Hydroxyapatite are an effective alternative to fluoride in cavity prophylaxis and safe when swallowed. ▲ , ᔐ
Together with the renowned cardiologist Prof. B.T. Amaechi and colleagues from UT Health San Antonio in Texas, we were able to demonstrate in 2019 that toothpaste with HAP remineralizes cavities down to deep layers. ⌘ And in 2020, that a HAP gel is equally as effective in remineralization as a high-concentration fluoride gel. ◓
BioHAP is just as effective as fluoride in caries prevention.▲
The gel with BioHAP was just as effective in remineralizing caries as the fluoride-containing adult toothpaste (88% caries-free patients).◓
The results of the study showed that the average amounts of toothpaste used by parents were significantly higher than the rice grain-sized recommended dose.
For toothpaste with BioHAP, there are no dosage restrictions.
The study shows that parents overdose fluoride-containing toothpastes. This leads to increased fluoride intake, which can result in fluorosis.△
BioHAP repairs the enamel and remineralizes small lesions evenly down into the underlying layers of the tooth.
In this way, BioHAP also protects against the development of new cavities.
The microcrystalline structure of BioHAP forms a protective layer on the tooth surface during dental care.
Acids and bacteria cannot attack the enamel directly.
Together with dentist Dr. Barbara Simader, we explored the question "Can we skip brushing our teeth thanks to mouthwashes?" in her review paper on active ingredients in toothpastes and mouthwashes (2019). ᛞ
In collaboration with a Polish research team led by Prof. Dr. Elżbieta Paszyńska and together with American and German colleagues, we were able to confirm in a one-year clinical multicenter study that children's toothpaste with BioHAP protects against cavities just as effectively as a fluoride-containing toothpaste. ᒥ
During bacterial acid attacks, BioHAP releases calcium, which maintains the healthy mineralization of the enamel and reduces the tooth-damaging acidic pH value in the oral cavity.
The bacteria in the oral cavity are bound by BioHAP and prevented from forming a biofilm on the teeth – but not killed.
In this way, BioHAP helps to keep the oral flora in its natural balance.
