应力水平对猪颞下颌关节盘生物力学特性的影响

研究颞下颌关节盘对压缩载荷的反应性 ,了解关节盘的粘弹性和渗透性质 ,为分析关节盘的应力缓冲机制提供实验依据。采用围限压缩力学实验方法 ,对三种不同应力水平 (0 .0 7、0 .12、0 .30MPa)下 8个猪颞颌关节盘的蠕变效应进行研究。结果表明 :在 0 .0 7MPa应力水平 ,关节盘前、中、后带承受压缩载荷 2s时的压缩刚度分别为 4.48、3.93、6 .31MPa,盘后带压缩刚度最大 ;渗透系数K值分别为 0 .2 72× 10 12 、0 .30× 10 12 、0 .0 42× 10 12 m4 /NS ,后带值明显低于前带。在 0 .30MPa水平 ,前、中、后带刚度分别增至为 14.0 7、16 .6 8、14.0 0MPa,渗透系数分别减小为0 .0 17× 10 12 、0 .0 12× 10 12 、0 .0 0 5× 10 12 m4 /NS ,各带之间无明显差异。颞颌关节盘是具有粘弹性的生物二相体 ,有一定抗压强度和较低的渗透性 ,应力水平增加 ,整体压缩刚度增大而渗透系数减小。提示对压缩刚度和渗透性的调节可能是关节盘组织内部承受并缓冲应力的两种方式。

Effects of Stress Level on the Biomechanical Behavior of the Temporomandibular Joint Disc in Domestic Pigs

This study aimed to examine the responses of the temporomandibular joint (TMJ) disc against compression, to clarify the property of viscoelasticity and permeability of the disc, and to provide experimental data for further analyzing the mechanism of stress dissipation within the TMJ disc. With the use of confined compression mechanics and biphasic theory, creep experiments on eight TMJ discs of four domestic pigs were performed under three stress levels(0.07 MPa, 0.13 MPa and 0.30 MPa). The results showed that at 0.07 stress level, the compressive stiffness at 2 seconds of the anterior band(AB), intermediate zone(IZ) and posterior band(PB) of the disc was 4.48 MPa, 3.93 MPa and 6.31 MPa, respectively; the coefficient K of permeability was 0.272 x 10(-12) m4/NS, 0.30 x 10(-12) m4/NS, and 0.042 x 10(-12) m4/NS. At 0.30 Mpa level, the compressive stiffness increased to 14.07 MPa, 13.68 Mpa and 14.00 MPa; the coefficient K lowered to 0.017 x 10(-12) m4/NS, 0.012 x 10(-12) m4/NS and 0.005 x 10(-12) m4/NS. In conclusion, the TMJ disc has viscoelastic and biobiphasic properties against compression. The stiffness of the disc increases with the increment of stress level but the coefficient of permeability decreases. These findings demonstrate that the modulation of stress and of permeability may be two important factors influencing stress dissipation and shock absorption behavior of the disc during compressive and impact loads.