[Relations of mechanical properties of human mandible to strain rate and density under tension load].
OBJECTIVE
To study the biomechanical properties of human mandible under tension load and deduce the constitutive equation.


METHODS
100 specimens taken from five mandible of fresh human cadavers were examined on INSTRON by a group of tensile tests at different strain rates (0.0003/s, 0.0030/s, 0.0300/s, 0.3000/s). Bone mineral density of every individual mandible was measured. The effect of strain rate (epsilon), bone mineral density (rho) on young modulus (E), strength (sigma u) and ultimate strain (epsilon u) was studied and the constitutive equation was deduced using the following model: Y = a rho b epsilon c.


RESULTS
(1) sigma u = 126.36 rho 1.88 x epsilon 0.044 (P < 0.01), (2) E = 25,170.97 rho 0.44 x epsilon 0.052 (P < 0.01), (3) epsilon u = 0.0088 rho 1.89 x epsilon -0.028 (P < 0.01), (4) sigma u = 6,309.57 rho 0.96 epsilon 0.056 x epsilon 0.80 (P < 0.01).


CONCLUSIONS
Strain rate and bone mineral density are important factors for the biomechanical properties of human mandible under tension load. The results above may modelize and characterize the constitutive relation within small strain rates. From the constitutive equation, we could estimate the stress level of the mandible and assess the possibility and degree of mandible injury.
Bo
B
B
Department of Oral and Maxillofacial Surgery, College of Stomatology, Fourth Military Medical University, Xi'an 710032, China.
Zhou
S
S
Li
L
L
D001696:Biomechanical Phenomena; D015519:Bone Density; D006801:Humans; D008334:Mandible / Q000502:physiology*; D013314:Stress, Mechanical