He Y, et al. - Researchers sought to develop numerical and experimental methods that may assist in investigating the formation of micro-gaps and the change in contact area at the implant-abutment interface of two different connector designs under oblique cyclic loading. Cyclic loading with increasing load amplitudes up to 220 N was undertaken on samples (n = 10 per group) of two-piece implant systems with the conical connection (group A) and the external hexagonal connection (group B). Micro-CT, with silver nitrate as a high-contrast penetrant, was used to scan the samples after loading, and a discrete scoring system was used to assess the level of leakage. To reveal the micro-gap formation process, especially bridging of the internal abutment screw space, they undertook three-dimensional finite element (FE) analyses of the two implant systems. Outcomes revealed good agreement between the FE-predicted loads for bridging and those found experimentally for leakage to occur. They identified higher resistance against formation of micro-gaps at the implant-abutment interface in the conical connection than the external hexagonal connection.