The aim of this RCT was to verify the caries preventive efficacy of toothpastes containing biomimetic hydroxyapatite (H.A.) complex in children compared to traditional fluoridated toothpastes. In total 610 children of two age groups (4-5 years and 6-7 years at baseline) were enrolled. Four toothpastes, two containing fluoride-substituted hydroxyapatite (H.A.F.) (1000 and 1450 ppm F-) and magnesium-, strontium-, carbonate-substituted hydroxyapatite, in a chitosan matrix and two traditional fluoridated toothpastes (1000 and 1450 ppm F-) without other active components were administered randomly to two groups with younger children (Gyoung) and to two groups with older children those containing1450 ppm F (GOLD) during 24 months. A standardized questionnaire was administered to parents/caregivers to gain information regarding caries risk factors. Caries evaluation was performed at school using ICDAS, scoring lesions as initial (up to score 2), moderate (scores 3-4) and severe (scores 5-6).

Inclusion Criteria:

• Written declaration of informed consent signed by parents/guardians;
• Age between 4-5 years and 6-7 years; Good general health, as assessed by the examiners;
• Agreement of not to use any oral hygiene products except for the toothpastes provided for the duration of the study.

Exclusion Criteria:

• Ongoing oral or dental treatment except for emergency treatment;
• Known allergic reaction to an oral hygiene product and/or medication and/or dental material previously used in the mouth or pharynx;
• Allergy to one of the components of the test products or the standard toothpaste;
• Participation in another clinical trial either currently or within the last 30 days;
• Antibiotic therapy within the past 3 months.