3D finite element study of biomechanical performances of short implant supporting fixed prosthesis

All-on-four oral rehabilitation by placing 2 tilted splint with 2 normal angulation implants, is one of an effective treatment but operator's experience are more required. Using short implant (not greater than 6 mm.) instead of tilted implant placement may interest. The purpose of this study is to evaluate the biomechanical performances of short implant for supporting fixed prosthesis in edentulous maxilla. Finite element models were designed into 3 conditions. In anterior region, two 4.1×8 mm. implants were used. In posterior region, a couple of short implant (4.1×6 mm. and 4.8×6 mm.) were used in condition 1 and 2, respectively. While condition 3 (original All-on-four) 2 pieces of 4.1×8 mm. implant were placed with 30° angulation. Both axial and oblique loading directions were applied with a magnitude of 150 N. at the first molar area. Strain, stress, strain energy density (SED), and implant displacement were evaluated. Results revealed that the strain, stress, and displacement from each condition were not greater than 4000 microstrains (bone's maximum strain value before resorption), 104 MPa (bone's yield strength), and 5 micrometers (physiologic movement of implant), respectively. The results indicated that marginal bone would not be affected. The application of short implant could safe to the bone in biomechanical aspect.