Biomechanical effects of inclined implant shoulder design in all-on-four treatment concept: a three-dimensional finite element analysis.

Abstract

The aim of the present study was to assess thebiomechanical behaviour of using a posterior implant design with inclined shoulder designs in all-on-four treatment via three-dimensional finite element analysis. Implants with standard and inclined shoulder designs were modelled for posterior implants. Implants were positioned into the maxilla and mandible models according to the all-on-four concept. Compressive stresses in the peri-implant bone, the von Mises stresses in the different components of the prosthetic restoration, and movement of the prosthesis were obtained. The compressive stresses of the models with inclined shoulder design resulted in 15-58 % decrease compared with standard shoulder design. The von Mises stresses in the posterior implants reduced 18-47 %, stresses in the implant body increased 38-78 %, stresses in the abutment screw reduced 20-65 %, stresses in the framework of prosthesis reduced 1-18 % and deformation of the prosthesis was reduced 6-37 % in the models of inclined shoulder designcompared with models of standard shoulder design. The compressive and von Mises stresses were generally higher in the mandible models than in the maxilla models forstandard and inclined shoulder designs. All evaluated components of the simulated treatment except for posterior abutment bodies showed better biomechanical behaviour with inclined shoulder design. The clinical success of all-on-four treatment maybe enhanced by using posterior implants with an inclined shoulder design.