The prevalence of caries on the proximal tooth surface is high and the interdental location of the lesion a challenging site for treatment. In this study patients with early proximal caries (E1 and E2) are treated with the regenerative product Curodont™ Repair. It contains P11-4, a self-assembling-peptide (SAP), that is applied as a solution onto the lesion surface. P11-4 then diffuses into the subsurface body of the early carious lesion where it forms a 3-D fibril network. In the process of a few months Ca2+ and PO43- ions, excessively present in the patient's saliva, attach to the nucleation sites of the P11-4-network and induce formation of de novo hydroxyapatite (HA) crystals [1]. The aim of the present study is to evaluate the efficacy of Curodont™ Repair in respect to regenerate enamel in patients with early proximal caries. Keywords: carious lesion, regeneration, hydroxyapatite, remineralisation