Anisotropic elastic properties of cancellous bone from a human edentulous mandible

The elastic moduli have not been reported for cancellous bone from the eden tulous mandible. Accurate values are needed for finite element modeling of the mandible. The aim of this study was to determine elastic modulus values in three orthogonal directions for cancellous bone taken from an edentulou s jaw and to relate these values to apparent density and volume fraction. S even samples were obtained from the edentulous mandible of a 74-year-old fe male. Young's modulus was determined by compression testing of cubes cut wi th the faces aligned with the anatomic axes. Bone volume fraction averaged 0.33 (SD 0.14) and apparent density averaged 0.55 g/cc;(SD 0.29). Young's m odulus was greatest in the mesio-distal direction (mean 907 MPa, SD 849 MPa ), followed by the bucco-lingual (mean 511 MPa, SD 565 MPa) and infero-supe rior direction (mean 114 MPa, SD 78 MPa). The infero-superior direction was less than the buccolingual (P=0.03) and mesio-distal (P=0.002). The mesio- distal and buccolingual directions could not be shown to be different (P=0. 32). This suggests a model of transverse isotropy for cancellous bone in th e jaw, where the symmetry axis is along the infero-superior (weakest) direc tion.