During chewing, forces are generated on the prosthesis. If a chewing force is acting along the axis of an implant (axial force), the stress will be evenly distributed through the implant cross-section and the fixture threads.
In any structure subjected to functional loads, there may be situations leading to overload and subsequent complications. Implant treatment defines a structure based on both biological tissue (bone) and mechanical components (implant and superstructure). Overload in this biomechanical edition where chewing forces exert a repeated bending of a part of this structure leading to marginal bone loss and/or component failure.
Teeth are anatomically unique because they are the only structures of the body that penetrate a lining or covering epithelium. Thus, teeth and dental implants are two isolated examples of structures that pierce the integument. While proper anchorage of an implant in the bone (osseo-integration) is a prerequisite for its stability, long-term retention of an implant seems to depend on the epithelial and connective tissue
attachment to the titanium surface, ie, a complete soft tissue seal protecting the bone from the oral environment.