大鼠牙槽骨理想模型的流固耦合数值模拟研究

Fluid-solid coupling numerical simulation on ideal porous structure of rat alveolar bone

载荷作用下松质骨孔隙中的液体流动是刺激骨组织细胞产生生物学响应并调控骨重建的主要因素。因此,阐明牙槽骨内孔隙结构中的液体流动情况对于深入理解力学作用在牙槽骨内的传导过程以及牙齿发育、正畸牙移动等细胞水平的调控机制具有重要意义。此工作首先进行了大鼠牙齿正畸的动物实验,并基于微计算机断层扫描(micro-CT)图像构建了牙齿-牙周韧带-牙槽骨有限元模型,分析了咬合力或正畸力作用下牙槽骨中的应变状态;进而构建了理想模型,应用流固耦合数值模拟方法,分析了动态咬合力加载下无正畸加载、正畸拉伸加载、正畸压缩加载三种情况下骨内液体的流动情况。模拟结果表明,动态咬合力作用下,沿咬合方向排列的骨小梁表面流体剪应力水平高于非咬合方向排列的骨小梁,正畸力对骨内液体的流动没有影响。上述结果说明,临床上通过调整牙齿咬合面形状等方法改变咬合力的方向,会在牙槽骨表面引起不同水平的流体剪应力,进而刺激骨组织表面的细胞产生响应,最终调控牙槽骨的结构重建。

Fluid shear stress(FSS)caused by interstitial fluid flow within trabecular bone cavities under mechanical loading is the key factor of stimulating biological response of bone cells.Therefore,to investigate the FSS distribution within cancellous bone is important for understanding the transduction process of mechanical forces within alveolar bone and the regulatory mechanism at cell level during tooth development and orthodontics.In the present study,the orthodontic tooth movement experiment on rats was first performed.Finite element model of tooth-periodontal ligament-alveolar bone based on micro computed tomography(micro-CT)images was established and the strain field in alveolar bone was analyzed.An ideal model was constructed mimicking the porous structure of actual rat alveolar bone.Fluid flow in bone was predicted by using fluid-solid coupling numerical simulation.Dynamic occlusal loading with orthodontic tension loading or compression loading was applied on the ideal model.The results showed that FSS on the surface of the trabeculae along occlusal direction was higher than that along perpendicular to occlusal direction,and orthodontic force has little effect on FSS within alveolar bone.This study suggests that the orientation of occlusal loading can be changed clinically by adjusting the shape of occlusal surface,then FSS with different level could be produced on trabecular surface,which further activates the biological response of bone cells and finally regulates the remodeling of alveolar bone.