Evolving interfaces: A comprehensive review of implant-abutment connections

Studying the implant-abutment connection is crucial, as it primarily determines the strength and stability of an implant-supported restoration, which, in turn, affects prosthetic stability. Traditionally, Brånemark's external hexagon has been used. However, significant complications such as abutment screw loosening, rotational misfit at the implant-abutment interface and microbial penetration have necessitated modifications of the external hexagon and led to the development of internal implant-abutment connection. This review outlines the evolution of various implant-abutment connections from the traditional external hexagon to advanced internal designs. Internal interface designs offer several advantages over the traditional approach. They reduce the vertical height platform for restorative components and distribute lateral loading deep within the implant. These designs also shield the abutment screw and provide long internal wall engagements that create a rigid, unified body resisting joint opening. Additionally, they feature wall engagement with the implant that buffers vibration, offer the potential for a microbial seal, and provide extensive flexibility. Importantly, they allow for the lowering of the restorative interface to the implant level for better aesthetics. These advancements have significantly enhanced the clinical performance and reliability of implant-supported restorations.