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1988
Conference Paper
Titel
Influence of the implant shape on the stress distribution in bone
Abstract
The stress distributions generated by dental implants in the surrounding bone were calculated by means of the finite-element technique for different implant shapes, loading situations and interface conditions. Five principally differing shapes were investigated; they were chosen to be representative for the typical axi-symmetric systems used at present: cylindrical (corresponding e.g. to IMZ-or TCP-implants), conical (similar to a tooth root) stepped (comparable to the type Tübingen), screw-shaped (e.g. like TPS-, Branemark-, Biolox-or CBS-screws) and hollow-cylindrical (comparable to the ITI-system). In order to exclude additional size effects, the shapes were normalized to equal length and maximum diameter. The loading direction was normally chosen parallel to the implant axis, in some cases also perpendicular to it. The interface conditions between bone and implant were assumed to simulate pure contact (only transfer of compression) or ongrowth in the spongy part (fixed bond, i.e. a dditional transfer of tensile and shear-stresses). The results exhibit remarkable differences between the different shapes. The highest stresses are generated by the conical implant under axial load and pure contact conditions (Fig. 2). In the latter case the radii of curvature play an important role. All stress peaks are additionally, however, differently diminished by a fixed ingrowth in the spongy region of the jaw (Fig. 3). Horizontal loading perpendicular to the implant axis does not produce such significant differences between the various shapes (Fig. 3). Thus, investigations under axial load will deliver the better criterion for evaluating the shape.