Abstract. Several surgical techniques like are today available in order to recovery large bone defects of the jaw. Aim of the surgeon is to obtain a good tridimensional volume to place dental implant and to recovery the patient's aesthetics and function. Several prosthetic solution were considered for prosthetic rehabilitation. However after a bone graft surgery Toronto screwed prosthesis on dental implants, following Branemark intuitions, was considered the better prosthetic rehabilitation solution. According to Wölff, the dental implants osteointegration is related to the strengths directed to mandibular bone. Our investigation's aim is to underline through FEM analysis the stress over the prosthetic elements and over bone surface in order to help the surgeon choice about the dental implant positioning, and at the same time reducing the bone trauma on the patients.