The effects of implant length and diameter prior to and after osseointegration: a 2-D finite element analysis

A two-dimensional finite element analysis was used to evaluate the effects of implant length and diameter on the stress distribution of a single-implant supported crown and the strain distribution of its surrounding bone prior to and after the phase of osseointegration. The effect of length was investigated using implants with a diameter of 3.75 mm and lengths of 8 mm, 10 mm, 12 mm, and 14 mm. The effect of diameter was investigated using implants with a length of 10 mm and diameters of 3 mm, 3.75 mm, 4.5 mm, and 5mm. The phase prior to osseointegration was simulated by assuming a coefficient of friction for the interface between the implant and the surrounding bone, while the phase after osseointegration was simulated by assuming a fixed bond on the interface between the implant and the surrounding bone. The FEA results indicated a tendency towards stress reduction on the implant, both prior to and after osseointegration, when the length was increased. However, the calculated stresses on the implant were lower after the phase of osseointegration. Although no specific correlation could be seen regarding the influence of implant diameter, the calculated stresses on the implant were again lower after the phase of osseointegration. For all these cases, the maximum stress concentration occurred at the abutment-implant interface. As far as bone tissue was concerned, there was a tendency towards strain reduction, before and after osseointegration, when the length of the implant was increased from 10 mm up to 14 mm. This tendency was not manifested for the range of 8 to 10 mm. The effect of implant diameter on bone tissue was not clear. It appears that implants of a diameter more than 5 mm are not preferable for immediate loading. Finally, it seems that cortical bone is not influenced by the phase of osseointegration, while trabecular bone is highly affected.