The aim of this pilot study is to analyze if a hydroxyapatite-containing mouth gel has an influence on the calcium content of plaque.

>= 20 subjects (7-11 years) use the hydroxyapatite-containing mouth gel for 3 days (3x per day); without using any other oral care product at this time. A dentist applies the gel on all teeth. At baseline and after 3 days plaque will be collected from buccal and labial surfaces (except surfaces with tartar). A "split-mouth" concept will be used:

Subjects in group A:

Baseline plaque collection: quadrant 1 and 4 Plaque collection after 3 days: quadrant 2 and 3

Subjects in group B:

Baseline plaque collection: quadrant 2 and 3 Plaque collection after 3 days: quadrant 1 and 4 (The time between last application of the gel and plaque collection will be 1 h) The plaque will be dried and afterwards the calcium content of the plaque will be quantitively analyzed by atomic absorption spectroscopy (AAS).

For all subjects: Calcium contents of plaque at baseline and after 3 days application will be compared by statistical methods.

Inclusion Criteria:

• Girls and boys (7-11 years)
• Visible plaque
• >= 4 teeth
• Good overall health

Exclusion Criteria:

• Allergic to one or more ingredients of the mouth gel
• Medication intake (e.g. antibiotics)
• Any other reason that, in the opinion of the investigator, disqualifies the subject from participating in the study