Influence of arch shape and implant position on stress distribution around implants supporting fixed full-arch prosthesis in edentulous maxilla

Purpose: This finite element analysis was conducted to determine changes in stress concentration in relation to different alveolar arch shapes of the maxilla. Materials and Methods: Five different maxillary alveolar arch shape measurements coded as shortest ellipsoid shape and medium width, longest ellipsoid shape and narrow, U-shaped long and narrow, U-shaped short and wide, and U-shaped medium length and medium width were obtained, and 5 different implant distribution strategies coded on the basis of a tooth number as 3,4,5; 2,3,4; 1,3,5; and 2,4,5 (total of 6 implants) and 2,3,4,5 (total of 8 implants) were plotted in each of the 5 maxillary arch models. The implants were assumed to support a 12-unit bridge with first molars region being the cantilever area. Combination of 5 different arch shapes, 5 different implant distributions, and 2 different loading points (anterior and posterior) led to 50 different simulated scenarios that are all solved and compared. Results: In case of either anterior or posterior loading, the most favorable implant distribution strategies for the arch models are as follows: 2,4,5 and 2,3,4,5 for longest ellipsoid shape and narrow; 2,4,5 and 2,3,4,5 for shortest ellipsoid shape and medium width; 1,3,5 and 2,3,4,5 for U-shaped long and narrow; 2,3,4,5 and 2,4,5 for U-shaped medium length and medium width; and 1,3,5 and 2,3,4,5 for U-shaped short and wide. Conclusions: Distribution of implants in 2,4,5 order seemed to be fairly favorable for ideal stress distribution in all simulated models.