Investigation of stress distributions of implants with different lengths and inclination angles with the all on four concept: A finite element analysis

In our study, it is aimed to compare implants with different lengths and inclination angles with finite element analysis under immediate and delayed loading conditions according to apply the all on four concept. The anterior implant was placed in the vertical direction and 13 mm in length in each model, the posterior implant was placed in 2 different lengths, 13 mm and 15 mm, and 2 different application angles at 30 and 45 degrees so that 4 different models were obtained by 3 dimensional finite element analysis method. A total of 8 models were evaluated by comparing the obtained models under immediate and osseointegrated loading conditions. Each model is completed with a cobalt-chrome framework material with fixed prosthetic restoration. Bilateral force of 100 N was applied to the first molar at an angle of 30 degrees in the buccolingual direction and von mises stress of implants and principal stress of cortical and trabecular bone was evaluated. Delayed models showed smaller stress values on the cortical bone, trabecular bone and implants, respectively. In models placed at an angle of 30 inclination angles, higher stress formation was observed in cortical and trabecular bone compared to 45 degrees. It has been observed that the insertion angle affects the stress distribution more than the implant length.