Effect of post-osseointegration loading magnitude on the dynamics of peri-implant bone: a finite element analysis and in vivo study

Purpose: Much research has been invested in determining the effects of postoperative loading of implants and whether this loading contributes to implant failure, but the issue remains controversial. The present study aimed to elucidate whether cyclic lateral loading of an implant causes bone resorption or bone formation at various loading magnitudes, using a finite element method (FEM) and peri-implant morphologic and morphometric analyses. Methods: An FEM model was created using Digital Imaging and Communications in Medicine (DICOM) data of rabbit tibia. For the animal study, implants were inserted into rabbit tibia and, after osseointegration, were subjected to lateral cyclic loading of 20N, 40N or 60N. Results: Bone-implant contact was significantly higher in both 40N and 60N groups. Bone–abutment contact (BAC) was extraordinarily observed in all experimental groups. Bone height was higher than the implant platform level at higher levels of loading (60 N). Among the three experimental groups, those receiving 40 N loading had the highest bone height and BAC. Larger BAC values were observed on the compressive side than the tensile side. Conclusions: Peri-implant bone formation was enhanced with increased loading, with bone formation predominantly on the compressive side. BAC was highest in the 40 N group, implying existence of a loading threshold for peri-implant bone formation and resorption.