The purpose of this study is to evaluate the therapeutic benefit of Curodont Repair for the treatment of early approximal carious lesions compared to fluoride.

All study participants must have two early approximal carious lesions in need of a treatment but not of an invasive treatment (split-mouth design). One lesion will be treated with Curodont Repair and one with fluoride as control. Study duration is 24 months. For assessment x-ray pictures, Diagnodent Pen and DiagnoCam is used.

Inclusion Criteria:

1. Two approximal carious lesions on different teeth with at least one tooth in between

2. Both study lesions must not require an invasive treatment

3. Size and form of the lesions: the lesions must be fully visible and assessable on radiographs

4. The two carious lesions must fall into classes:

   • D2 (inner half of enamel)
   • D3 (outer part of dentine) but only if very little dentine is involved (enamel-dentine junction)

5. Able and willing to observe good oral hygiene throughout the study

6. Age ≥ 18 years and ≤ 65 years

7. Willing and able to attend the on-study visits

8. Willing and able to understand all study-related procedures

9. Written informed consent before participation in the study

Exclusion Criteria:

1. The two study test lesions are located on adjacent teeth
2. Fluoride varnish application < 3 months prior to study treatment
3. Tooth with numerous carious lesions
4. Evidence of tooth erosion
5. History of head and neck illnesses (e.g. head/neck cancer)
6. Any pathology or concomitant medication affecting salivary flow or dry mouth
7. Any metabolic disorders affecting bone turnover
8. Patient suffers from diabetes
9. Concurrent participation in another clinical trial
10. Women who are breast-feeding, pregnant or who plan a pregnancy during the study
11. Women of childbearing potential who declare being unwilling or unable to practice contraception such as hormonal contraceptives, sexual abstinence or intercourse with a vasectomised partner