Numerical investigations of the influence of implant shape on stress distribution in the jaw bone.

The stress distribution generated in the surrounding jaw bone was calculated and compared for different types of dental implants (cylindrical, conical, stepped, screw-shaped, hollow cylindrical) by means of the finite-element method. Both a fixed bond and a pure contact without friction between implant and bone were considered as interface conditions. The results demonstrate that different implant shapes lead to significant variations in stress distributions in the bone. In particular, implant surfaces with very small radii of curvature (conical) or geometric discontinuities (stepped) imply distinctly higher stresses than smoother shapes (cylindrical, screw-shaped). Moreover, a fixed bond between implant and bone in the medullary region (as may be obtained with a bioactive coating) will be advantageous for the stress delivered to bone, since it produces a more uniform stress distribution than does a pure contact.