Methods: Nine 3D-FEA models were constructed with identical implants (diameter 4.1 mm and length 10 mm): the first three models have the same vertical interarch space with different abutment lengths (4, 5.5, and 7 mm) ; models 4 to 6 have three different extents of interarch space with corresponding abutment lengths ; models 7 to 9 represent implants with identical abutments (2.5 mm) with screwed crowns and different extents of interarch space. The implants were placed in the center of a bony structure. Crowns were loaded with a defined force of 30 N inclined 30° chosen arbitrarily.
Results: Within the implant and bone, the most intense stresses appeared in the cervical area. Highest stresses occurred within the implants first at their neck, and progressively decreased towards the bone, the abutment, in the threaded part and the cervical area of the crown. Stress levels increased with the vertical interarch space, which is the dominating factor. Abutment height adaptation to the vertical interarch space is an important parameter.
Conclusions: In this mechanical context, the comparison allows preference to abutments designed for cemented crowns. Moreover, implant initial stability seems easier with short vertical interarch spaces.