Lasting adhesion between attachment and tooth is an essential prerequisite for all adhesive techniques in dentistry. However, the maximum static fatigue load is only one material-related parameter for the quality of this adhesion. Another parameter is the dynamic loading capacity of a bonded joint, which was determined in the present study for Dual adhesive resin by means of fatigue testing. This revealed a significant correlation between the recorded static and dynamic fatigue load and the gap width, which varied between 0.01 mm, 0.15 mm and 0.5 mm in the experimental setup. At 18.8 MPa, the median gap width of 0.15 mm yielded the highest static resistance, with a dynamic resistance 15% below this figure. Both the smaller and the larger gap showed significantly lower static fracture strengths (0.01 mm: 13.6 MPa; 0.5 mm: 13.7 MPa), whereas a dynamic load on the 0.01 mm bond, in contrast to the 0.5 mm bond, led to only a 5% reduction in bonding strength.
