Finite element analysis of non-axial versus axial loading of oral implants in the mandible of the dog.

The influence of axial and non-axial occlusal loads on the bone remodelling phenomena around oral implants in an animal experiment is simulated in a finite element analysis. The axial and non-axial loading conditions were introduced by inserting a bilaterally supported fixed partial prosthesis and a cantilever fixed partial prosthesis on two IMZ implants in the mandible of beagle dogs. Earlier quantitative and qualitative histological analyses revealed a statistically significant different remodelling response between both loading conditions. Two-dimensional and three-dimensional models are built to analyse and compare von Mises equivalent stress, maximum principal stress, maximum principal strain and strain energy density distributions, first around a free-standing implant and subsequently around the implants of the two prosthesis designs under the respective resultant in vivo loads. Strong correlations between the calculated stress distributions in the surrounding bone tissue and the remodelling phenomena in the comparative animal model are observed. It is concluded that the highest bone remodelling events coincide with the regions of highest equivalent stress and that the major remodelling differences between axial and non-axial loading are largely determined by the horizontal stress component of the engendered stresses.