Theree dimensional finite element analysis of different implant configurations for mandibular fixed prosthesis

Purpose: The distribution of stresses in bone, imp!ants, and prosthesis were anaiyzed via threed imensionai finite element modeling in different implant con figura tions for a tixed impiant-supported prosthesis in an edentulous mandible. Materlals and Methods: A finite element mode! was created with data obtained from computed tomographic scans of a human mandible. Anisotropic characteristics for cortical and canceiious bone were incorporated into the model. Six different con figurations of intraforaminal implants were tested, with the number of impiants varying from three to five and the distai impiants inserted either parallel to the other implants or tilted distaily by 17 or 34 degrees. A prosthetic structure connecting the impiants was designed, with 20-mm posterior cantilevers for the paraliel impiant con figura tions, and a load of 200 N was applied to the distai portion of the cantilevers. Stresses were measured at the ievei of the impiant, the prosthetic structure, and the bone. Bone-level stresses were analyzed at the impiant-bone interface, at the externai corticai bone surface, distai to the termina! impiant, and in the canceiious bone along the impiant body. Results: A three-parailei-impiant con figuration resuited in higher stress in the implant and bone than con flgurations with four or five paraliel implants. Con tlgurations with the distai impiants tiited resuited in a more favorabie stress distribution at ai! Ievels. Concluslon: In parallei-implant con figura tions for flxed implant-supported mandibular prostheses, four and five implants resuited in simiiar stress distribution in the bone, framework, and implants. A distribution of four impiants with the distai impiants tilted 34 degrees (le, the “Aii-on-Four” con figuration) resulted in a favorabie reduction of stresses in the bone, framework, and imp!ants.