In addition, there was not a significantly less strain site by offset placement. Anitua et al. have reported that offset placement did not affect marginal bone loss around the implant in the oral cavity of the living body. Overloading of the peri-implant bone has been reported to result in bone resorption, and the concentration of considerable stress in the load-side peri-implant bone observed in our study confirms this. Hence, we conclude that our observation that offset placement did not reduce the stress around the peri-implant bone in both the experimental and FEA models is similar to that of the clinical report by Anitua et al. In addition, we also conclude that our results confirm the validity of both analyses. Thus, offset placement may not necessarily be more biomechanically effective than straight placement.

Stress distribution

Concentration of stress in the loading-side peri-implant bone was observed in all placements and for both the experimental and the FEA models. Considerable stress was also found to be concentrated in the no. 36 peri-implant bone in buccal loading with buccal offset and lingual loading with lingual offset. Similar to the strain results, stress was observed in a large range under conditions where the loading site was far from the load-supporting area (Fig. 15).

Limitations of the study

This study does have a few limitations. The only items assessed in these experiments were the compressed displacement of the implant bodies and strain in the peri-implant bone. More specifically, the stress and strain applied to the implant bodies themselves, among other items, should be verified in order to verify the effects of offset placement. Moreover, the occlusal loading conditions and the jawbone models used in this study were different from those in the body, and hence, future studies addressing these limitations are needed.

In the present study, which aimed to verify the biomechanical effects of offset placement on peri-implant bone, we created multiple finite element models and models where implants were actually placed. We compared the compressed displacement as well as the strain and stress distribution in the peri-implant bone between both kinds of models, and the results can be summarized as follows:

1. Central loading resulted in the least compressed displacement in all placements in the experimental models as well as the FEA models.In both the experimental models and the FEA models, compressive stress was observed to be concentrated in the loading-side peri-implant bone.
2. The strain and stress was significantly greater under conditions of offset placement where the loading site was far from the load-supporting area.

These results suggest that compared to straight placement, offset placement is not necessarily more biomechanically effective.