The treatment of distal extension base removable partial denture has long been the dilemma of many Prosthodontists, since the support for this type of restoration is based on two functionally different systems, the teeth and associated periodontal membrane and the edentulous ridges. So one of their most elusive goals were to finish the prosthesis by utilizing both systems of support without exposing the tissues to undue stresses which might lead otherwise to bone resorption. Material and method: A two-dimensional finite element analysis method was used to assess the stress distribution on supporting structure where different rest position, including mesial-occlusal rest, distal-occlusal rest, and mesio-distal occlusal rest. The X, and Y coordinate for each node of the model was transferred to the ANSYS program, a load of 10MP was used in this study, where each of the models was subjected to load distributed on the saddle area. Results: Von Mises stress values revealed that, mesial rest produces less stress concentration,

Aim of the study: To study the effect of reduced level of bone support on stress concentration and distribution. Also comparing the effect of different metals (gold, cobalt-chromium, and titanium) on alveolar supporting bone. Material and methods: A FEA method is used on a reduced bone support class I Kennedy classification, with three different rest positions (mesial, distal, mesial and distal) Co-Cr partial denture; Then changing the modulus of elasticity of the chrome-cobalt, to study the effect of gold and titanium alloy on the supporting bone surrounding the abutment in terms of stress distribution. Results: results revealed that best design type is by placing mesial and distal rest on abutment, also when comparing the three types of metals (Co-Cr, titanium, gold), there was no significant difference among the three metals.