Zhang Chunyu, Wang Yuehong
Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha 410008, China.
Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha 410008, China.
J Funct Biomater. 2023 Nov 23;14(12):557. doi: 10.3390/jfb14120557.
The porous structure can reduce the elastic modulus of a dental implant and better approximate the elastic characteristics of the material to the alveolar bone. Therefore, it has the potential to alleviate bone stress shielding around the implant. However, natural bone is heterogeneous, and, thus, introducing a porous structure may produce pathological bone stress. Herein, we designed a porous implant with axial gradient variation in porosity to alleviate stress shielding in the cancellous bone while controlling the peak stress value in the cortical bone margin region. The biomechanical distribution characteristics of axial gradient porous implants were studied using a finite element method. The analysis showed that a porous implant with an axial gradient variation in porosity ranging from 55% to 75% was the best structure. Under vertical and oblique loads, the proportion of the area with a stress value within the optimal stress interval at the bone-implant interface (BII) was 40.34% and 34.57%, respectively, which was 99% and 65% higher compared with that of the non-porous implant in the control group. Moreover, the maximum equivalent stress value in the implant with this pore parameter was 64.4 MPa, which was less than 1/7 of its theoretical yield strength. Axial gradient porous implants meet the strength requirements for bone implant applications. They can alleviate stress shielding in cancellous bone without increasing the stress concentration in the cortical bone margin, thereby optimizing the stress distribution pattern at the BII.
多孔结构可以降低牙种植体的弹性模量，并使材料的弹性特性更好地接近牙槽骨。因此，它有减轻种植体周围骨应力遮挡的潜力。然而，天然骨是异质的，因此引入多孔结构可能会产生病理性骨应力。在此，我们设计了一种孔隙率呈轴向梯度变化的多孔种植体，以减轻松质骨中的应力遮挡，同时控制皮质骨边缘区域的峰值应力值。采用有限元方法研究了轴向梯度多孔种植体的生物力学分布特征。分析表明，孔隙率在55%至75%之间呈轴向梯度变化的多孔种植体是最佳结构。在垂直和倾斜载荷下，骨-种植体界面（BII）处应力值处于最佳应力区间内的面积比例分别为40.34%和34.57%，与对照组的无孔种植体相比分别高出99%和65%。此外，具有该孔隙参数的种植体中的最大等效应力值为64.4MPa，小于其理论屈服强度的1/7。轴向梯度多孔种植体满足骨植入应用的强度要求。它们可以减轻松质骨中的应力遮挡，而不会增加皮质骨边缘的应力集中，从而优化BII处的应力分布模式。
