Tensile and flexural moduli for human orbital wall bones - comparative study

The main aims of the current research were: (1) to analyze in detail the tensile modulus and ultimate tensile strength (UTS) of orbital wall bones separately for the left and right orbit of the same cadaver and (2) to compare the obtained results with a flexural modulus of the left and right orbit reported earlier by A. C. van Leeuwen et al. [14]. A set of 54 specimens of orbital superior and/or medial walls harvested from 16 human skulls (4 female, 12 male) were tensioned at 0.01 mm/s till fracture. The samples were taken always from both orbits of the same cadaver. For each sample, cross-section area, apparent density, tensile modulus, and UTS were identified. For pooled female and male group apparent density for right and left orbit was identified to be 1.59 (+/- 0.52 SD) g/cm 3 and 1.51 (+/- 0.48 SD) g/cm 3 , tensile modulus of 2028 (+/- 1729 SD) MPa and of 2706 (+/- 2812 SD) MPa, and UTS of 14.17 (+/- 15.00 SD) MPa and of 15.03 (+/- 11.44 SD) MPa, respectively. For tensile tests, there were no statistical differences between the left and right orbit for pooled male and female groups for (a) apparent density (Student's t -test p = 0.567), (b) UTS (Mann-Whitney U -test p = 0.350) and (c) tensile modulus (Mann-Whitney U -test p = 0.716). For bending tests, there were no statistical differences between the left and right orbit for the pooled male and female group for (a) orbital wall thickness (Student's t -test p = 0.811) and (b) flexural modulus (Mann-Whitney U -test p = 0.206). The comparative analysis between tensile and flexural moduli for pooled left and right groups (with no distinction for male and female) revealed no statistically significant difference (Mann-Whitney U -test p = 0.074). The maximum tensile modulus was 7279 MPa and 9913 MPa for the right and left orbit, respectively, and was similar to the maximum flexural modulus of 6870 MPa and 9170 MPa reported in an earlier study, for the right and left orbit, respectively.