Modification of osseointegrated implants for distal-extension prostheses

The use of a distal implant abutment splinted to a natural tooth by a fixed partial denture has been employed for distal-extension prostheses. There is a differential difference between the viscoelastic deflection of a natural tooth by its periodontal ligament, and the almost negligible elastic deformation of an osseointegrated implant. This difference may induce a fulcrum-like effect and overstress the implant. In this study a new modification of osseointegrated implants was proposed to counteract this problem. This modification was achieved by using a resilient layer material under the superstructure of the implant. Finite element modeling (FEM) was used to examine stresses and displacement distribution around a commercially available implant and one experimental implant with a resilient layer material. The results of this study showed that the new modification is a simple and efficient way to mimic the structural natural tooth unit. It also showed that it allowed movement of the superstructure without movement of the implant three times that of the nonresilient model.