The influence of bar position on implant-retained mandibular overdenture a three dimensional finite element analysis

To evaluate the effect of bar position in implant-retained mandibular overdenture on stress distribution induced in bone surrounding the implant, a three dimensional (3D) model is designed by simulating an edentulous mandible, restored with mandibular overdenture and retained by 4 widely separated implants. All parameters were fixed except for the position of the bar segments. Vertical and oblique loads were applied on one working side. The stress distribution around the implants in each case was recorded and compared to correlate the induced stress magnitude to the bar structure. Stress distribution induced in the bone surrounding the implants showed minimal changes under the application of vertical loads, while under oblique load, connecting the two anterior implants, resulted in a better stress distribution. Using a one piece bar connection or two pieces bar connection of the four widely separated implants might lead to posterior buccal bone resorption in the working side as the stresses induced bypassed the bone yield strength.