Objectives: To test the hypothesis that the application of rubber-dam increases the proximal contact strengths. Methods: 74 consecutive patients of our department without periodontitis, who needed a direct posterior composite restoration participated in this study. The proximal contact strengths (PCS) were electronically evaluated by measuring the frictional forces during the removal of a 50±5µm thick straight metal band. PCS were measured at the site next to the restoration (R) and at the corresponding contact of the contra-lateral quadrant (C), which was taken as control. Measurements were taken at baseline (R0/C0), after the application of the rubber-dam (R1/C1), after wedging (R2/C2), after the application of the restorative material (R3/C3), immediately after the removal of the rubberdam (R4/C4) and 10 minutes later (R5/C5). Differences over time were tested by ANOVA followed by the post hoc Scheffé-test and differences between test and control side by the Wilcoxon-test for paired samples (p=0.05). Results: PCS changed with time from 2.26±1.45N (R0) to 3.83±2.34N (R1), 2.68±2.38 N (R2), 3.54±1.87N (R3), 2.31±1.35N (R4) and 2.08±1.26N (R5; p Schlagwörter: rubberdam, proximal contact