the objective of this phase IV study: to establish the efficacy of elmex gel with a fluoride concentration of 1.25% compared with placebo by determining prevention of white spot lesions in patients wearing fixed orthodontic appliances.

314 healthy subjects undergoing orthodontic treatment will be examined. follow up will take place from bonding the appliance till debonding, at least 12 months and no more than 30 months.

tooth brushing with product (test product or control) once per week during the entire study.

4 times a year additional tray application of test product or control. subjects wiil clean their teeth with the toothpaste they usually use during the entire study.

toothbrush and a sandglass will be provided every 6 weeks

Inclusion Criteria:

• treatment plan: minimum of 10 teeth to be bonded labially at least 10 years old
• written declaration of informed consent

Exclusion Criteria:

• known allergy to components of test products
• handicapped patients who have difficulties brushing their teeth
• pathological desquamation changes
• known pregnancy, breast feeding
• eating disorders
• disease that effect dental hard tissue
• participation in another clinical trial either currently or within the lase 30 days