Atieh Momen A, Shahmiri Reza A
Sir John Walsh Research Institute, School of Dentistry, University of Otago, Dunedin, New Zealand.
J Oral Implantol. 2013 Apr;39(2):123-32. doi: 10.1563/AAID-JOI-D-11-00104. Epub 2011 Sep 9.
This study aimed to evaluate the effects of different tapering angles of an immediately loaded wide-diameter implant on the stress/strain distribution in bone and implant after implant insertion in healed or fresh molar extraction sockets. A total of 10 finite element (FE) implant-bone models, including 8.1-mm diameter implant, superstructure, and mandibular molar segment, were created to investigate the biomechanical behavior of different implant taper angles in immediate and delayed placement conditions. The degrees of implant taper ranged from 2° to 14°, and the contact conditions between the immediately loaded implants and bone were set with frictional coefficients (μ) of 0.3 in the healed models and 0.1 in the extracted models. Vertical and lateral loading forces of 189.5 N were applied in all models. Regardless of the degree of implant tapering, immediate loading of wide-diameter implants placed in molar extraction sockets generated higher stress/strain levels than implants placed in healed sockets. In all models, the von Mises stresses and strains at the implant surfaces, cortical bone, and cancellous bone increased with the increasing taper angle of the implant body, except for the buccal cancellous bone in the healed models. The maximum von Mises strains were highly concentrated on the buccal cortical struts in the extracted models and around the implant neck in the healed models. The maximum von Mises stresses on the implant threads were more concentrated in the non-tapered coronal part of the 11° and 14° tapered implants, particularly in the healed models, while the stresses were more evenly dissipated along the implant threads in other models. Under immediate loading conditions, the present study indicates that minimally tapered implants generate the most favorable stress and strain distribution patterns in extracted and healed molar sites.
本研究旨在评估即刻负重的大直径种植体不同锥度角度对种植体植入愈合或新鲜磨牙拔牙窝后骨组织和种植体应力/应变分布的影响。共创建了10个有限元（FE）种植体-骨模型，包括直径8.1 mm的种植体、上部结构和下颌磨牙节段，以研究不同种植体锥度角度在即刻和延期植入条件下的生物力学行为。种植体锥度范围为2°至14°，即刻负重种植体与骨组织之间的接触条件在愈合模型中摩擦系数（μ）设为0.3，在拔牙模型中设为0.1。所有模型均施加189.5 N的垂直和侧向加载力。无论种植体锥度如何，置于磨牙拔牙窝的大直径种植体即刻负重产生的应力/应变水平均高于置于愈合牙槽窝的种植体。在所有模型中，种植体表面、皮质骨和松质骨的von Mises应力和应变均随种植体主体锥度角度的增加而增加，但愈合模型中的颊侧松质骨除外。最大von Mises应变高度集中在拔牙模型的颊侧皮质支柱以及愈合模型的种植体颈部周围。种植体螺纹上的最大von Mises应力在11°和14°锥度种植体的非锥度冠部更为集中，尤其是在愈合模型中，而在其他模型中应力沿种植体螺纹更均匀地消散。在即刻负重条件下，本研究表明，最小锥度的种植体在拔牙和愈合磨牙部位产生最有利的应力和应变分布模式。
