This review article on early childhood caries (= milk tooth caries) shows that this disease is still a major challenge worldwide. Even in Germany, according to current figures, around 50% of first graders (6-7 years old) are affected.
High sugar consumption and inadequate dental care mean that bacteria can multiply and produce acids. The acids (primarily lactic acid) dissolve the tooth enamel, which in turn leads to the formation of holes and thus to caries. Deciduous tooth caries can progress faster than decay on permanent teeth: milk teeth have tooth enamel that is only about half as thick as permanent teeth (approx. 0.5 to 1 mm vs. approx. 1 to 2 mm). Baby teeth also have a less organized microstructure. The sugar-rich food shifts the ecological balance in the oral cavity and on the tooth surface: Interestingly, of the more than 600 known types of bacteria, many different types of bacteria can cause tooth decay. There is not one main culprit.
Prevention of deciduous tooth caries can be achieved through reduced sugar intake and appropriate dental care. When it comes to dental care, it is important that the parents give the children active support until they are able to brush their teeth thoroughly on their own. Fluoride is often used in toothpastes. 500 ppm fluoride is often recommended for children. However, it has been known since 2010 that caries prophylaxis can only be reliably proven from 1000 ppm fluoride. Since a toothpaste with more than 500 ppm fluoride increases the risk of fluorosis (permanent discoloration of the teeth) if swallowed, alternative approaches are in demand. These alternative approaches are based on biomimetic active ingredients: this also includes hydroxyapatite. Hydroxyapatite can prevent tooth decay and is harmless if swallowed.
Thus, among other things, the biomimetic (endogenous) active ingredient hydroxylapatite is particularly suitable for children for caries prophylaxis.
The original study can be read here: https://www.hindawi.com/journals/ijd/2018/1415873/