Comparative analysis of bone stresses and strains in the Intoss dental implant with and without a flexible internal post.

The clinical success of any dental implant is dependent upon the maintenance of good-quality bone supporting it. Previous studies have shown high values of strain around the neck of an implant under lateral loading. These high values may lead to fatigue damage and resorption in lower strength cancellous bone. In this study, the finite element method has been used to study the bone strain distribution around the following implants: (a) an Intoss dental implant, referred to as the 'standard' implant; (b) a comparative Branemark implant and (c) a modified Intoss implant with a central flexible post, referred to as the 'modified' implant. Three different bone distributions have been investigated under axial and lateral loading: (a) implant surrounded by cortical bone; (b) implant tip supported by cortical bone with a thin layer of cancellous bone along the length and top of the implant; (c) implant tip and top supported by cortical bone with a thin layer of cancellous bone along the remaining length. For the standard implant, similar maximum equivalent strain values were predicted for the bone surrounding a comparable length Branemark-type implant. Modification of the standard implant design to include a flexible central post resulted in a decrease in the maximum von Mises stresses and equivalent strains in the cancellous bone. It is postulated that this will reduce the likelihood of bone fatigue failure and subsequent resorption in this bone. Thus the proposed design change is predicted to be highly beneficial in terms of bone load transfer.