Evaluation of different prosthetic designs supported by 2,3 or 4 implants in edentulous mandibula by finite element stress analysis

Several implant treatment options have been described for mandibular edentulous patients. However, these treatments have several advantages and disadvantages. The aim of this study was to evaluate an anterior fixed-splinted implant-supported restoration with a bar clasp or a precision attachment posterior partial denture as an alternative restoration to the removable implant-supported locator, bar or All-On-Four using finite element analysis. In this study we prepared 15, three dimensional finite element models representing distal extension removable partial denture connected to an anterior fixed implant-supported prosthesis, locator and bar retained overdentures and All-On-Four built over 2, 3 and 4 implants. One-hundred N vertical and oblique forces were applied on the first molar teeth bilaterally. The stresses were investigated using the computer program. In all loading conditions, the highest maximum stress values were observed at the cortical bone around the neck of the implant. The principal stress values were higher in oblique loading than in vertical loading conditions. The ultimate attention should be paid in order to orient the chewing forces along the long axis of the implant. There is no reduction of the extreme principal stresses when the load is distributed over an increasing number of implants. An anterior fixed-splinted implant-supported restoration with a clasp or precision posterior partial denture is offered as an alternative restoration to the removable implant-supported bar or locator overdentures.