Biomechanical properties of the body and angle of the sheep mandible under bending loads

Abstract

The aim of the study was to compare the body and angle of the sheep mandible in terms of bone density and biomechanical competence under bending load conditions. Nineteen sheep mandibles were used in this study. The mandibles were separated at the symphysis into two halves. Three regions of interest on the body and angle of the hemi-mandibles were selected for measurements of bone mineral density (g cm(-2) ) by dual energy X-ray absorbtiometry. Biomechanical properties of the left mandibular body and right mandibular angle were measured by three-point bending test using a material testing machine. The load and deformation were recorded, and the load-deformation curves were obtained. The values of failure load (FL), yield load (YL), yield deformation (YD), postyield deformation (PD), stiffness, energy to yield point (EY) and energy to failure point (EF) were calculated with the analysis of load-deformation curves. Groups were compared using independent samples Student's t-test. The mandibular angle exhibited the lower bone density (-64%) and biomechanical properties (FL; -45%, YL; -40%, PD; -7% stiffness, -40% EY; -48% and EF; -34%) than the mandibular body under bending loads, and there was no significant difference in values of YD between the two regions. Our results show that the mandibular angle is weaker than the mandibular body under bending loads.