Karex gelée for cavity protection


Our modern diet with sugary foods and drinks that are frequently consumed across the day is counterproductive for healthy teeth. Simply brushing teeth with a toothpaste is often not enough for cavity protection. There is only minor decline in caries in children and young children for many years. Gels with a significantly higher fluoride content (approx. 10x as much as in toothpastes) are often recommended for additional cavity protection. However, these high-fluoride gels are not suitable for children under the age of 6 due to the toxic properties of fluoride. A gel with highly concentrated BioHAP may offer a remedy here.


Is a gel with highly concentrated BioHAP  as effective as a gel with a high fluoride content for remineralisation and cavity protection?

Material and methods

This double-blind study was conducted in the laboratories of the renowned American caries researcher Professor B. T. Amaechi. Enamel samples were treated in such a way that they develop an early form of caries. The samples were further treated in a cycle of storage in saliva (22 hours a day), acid challenge (2 hours a day) and product application (according to the manufacturer’s instructions) for a period of 28 days. There was also a control group that was stored in saliva in place of product application.

The samples were then observed with transverse microradiography, the gold standard for examining such carious lesions.


The gel with BioHAP was as effective as the highly concentrated fluoride gel in remineralizing the cavities. Saliva alone only showed a slight effect in repairing cavities in this pH-cycling model. BioHAP also results in deeper and homogeneous remineralisation compared with fluoride.

Remineralization of initial carious lesions
Fig. 1: Remineralization of initial carious lesions


The highly concentrated gel with BioHAP is suitable for children (from age 0 on) and adults who want to do more for their dental health and cavity protection than just brushing their teeth.

The publication of the study can be found here.

Source: Amaechi, B. T., AbdulAzees, P. A., Okoye, L. O., Meyer, F. & Enax, J. Comparison of hydroxyapatite and fluoride oral care gels for remineralization of initial caries: a pH-cycling study. BDJ Open 6, 9 (2020).