多孔结构钛种植体对周围骨组织应力分布影响的三维有限元分析

发布时间：2018-08-31 11:51

【摘要】：背景:钛种植体因其弹性模量远高于周围骨组织,而易在种植体周围产生应力遮蔽效应,造成种植体周的骨吸收和骨萎缩。为减轻钛种植体的应力遮蔽效应,许多学者通过在钛种植体中构建骨样多孔结构,以降低种植体的弹性模量。研究表明多孔结构为骨细胞黏附和生长提供了更多的空间和表面积,提高骨结合率,具有优良的生物相容性。此外,良好的生物力学性能也是种植体成功的关键。三维有限元分析法是国内外研究种植体生物力学性能的有效方法之一。目的:本实验在课题组前期研究基础上,通过分析内部实心外部不同孔隙率的钛种植体在不同力学负荷作用下对不同类型的骨质应力分布的影响,以进一步评估多孔结构钛种植体的生物力学性能,从而为不同孔隙率的内芯致密外层多孔结构的钛种植体的临床应用提供力学参考依据。方法:1.建立Ⅲ类骨骨块、上颌第一前磨牙牙冠模型、基台与种植体模型,种植体分为实心、孔隙率30%中央支柱1.5mm、孔隙率30%中央支柱3.1mm、孔隙率40%中央支柱1.5mm、孔隙率40%中央支柱3.1mm五组,分别合面中央窝施加150N垂直力,在颊尖舌斜面施加50N侧向力、模拟极限合力(轴向114.6N,颊舌向17.1N,近远中向23.4N),评估不同负荷下多孔结构钛种植体周围骨的应力分布情况。2.建立Ⅰ类骨、Ⅱ类骨、Ⅲ类骨、Ⅳ类骨骨块模型,种植体分组同方法1,模拟极限合力加载,评估多孔结构钛种植体对不同类型骨质的应力分布情况。结果:1.实心种植体和多孔结构种植体在不同类型骨组织中的应力分布模式相似,即垂直加载下应力集中区域主要位于种植体颈部周围的皮质骨,呈环形分布,.侧向力加载下周围骨组织应力集中在颈部颊侧皮质骨,种植体中段及下段周围骨组织所受应力较为均匀。2.随着孔隙率的增加,种植体周围骨组织的高峰应力值面积相应减少,当孔隙率达到40%时,高峰应力值面积减少得更为明显。3.不同力学负荷加载下,各组模型中均观察到多孔钛种植体骨界面所承受的最大应力值要大于实心结构种植体。种植体周围骨组织的最大应力值均位于种植体颈部的皮质骨;且随着施加力学负荷的增大,各组种植体周围骨组织的最大应力也相应增大。侧向力加载下的种植体周围骨界面所承受的最大应力值要远高于垂直力加载下所受的应力。4.随着种植体多孔层孔隙率的增加,种植体骨界面的最大应力值增加;相同孔隙率的多孔钛种植体,多孔层越厚,即中间支柱直径越小时,其骨界面所受最大应力值越大。5.无论是实心还是多孔结构种植体,其周围骨组织最大应力值随着骨质的变化而变化,Ⅳ类骨Ⅲ类骨Ⅱ类骨Ⅰ类骨。结论:1.不同力学负荷加载下,各组模型中均观察到多孔钛种植体周围骨组织所承受的最大应力值要大于实心结构种植体,且随着孔隙结构的增多,种植体周围骨组织所受应力也随之增大。无论是实心还是多孔结构种植体,其周围骨组织最大应力值均随着骨质的变化而变化,骨质密度越低,种植体周围骨组织所承受的最大应力值越大。侧向力对种植体周围骨组织所产生的应力比垂直力大。2.骨质越致密,咬合力越小时,多孔结构相对实心结构更有利于应力向周围骨组织传导,增加种植体周围骨组织所承受的应力,以抵消应力遮蔽。3.骨质越疏松,咬合力力值越大时,对多孔结构种植体的使用越要谨慎,严格控制侧向力及过大咬合力,以防止病理性载荷的产生。
[Abstract]:BACKGROUND: Titanium implants are prone to produce stress shielding effect around the implants because their elastic modulus is much higher than that of the surrounding bone tissues, resulting in bone resorption and bone atrophy. The results show that the porous structure provides more space and surface area for osteocyte adhesion and growth, improves bone binding rate and has excellent biocompatibility. In addition, good biomechanical properties are also the key to the success of implants. Based on the previous research of our research group, the effects of different internal and external porosity of titanium implants on the stress distribution of different types of bone under different mechanical loads were analyzed in order to further evaluate the biomechanical properties of porous titanium implants, so as to compact the inner core and outer porous structure with different porosity. Methods: 1. Establish three kinds of bone mass, maxillary first premolar crown model, abutment and implant model. The implants were divided into five groups: solid, porosity 30% central pillar 1.5mm, porosity 30% central pillar 3.1mm, porosity 40% central pillar 1.5mm, porosity 40% central pillar 3.1mm. A 150 N vertical force was applied to the central fossa and a 50 N lateral force was applied to the oblique surface of the buccal tip and tongue to simulate the ultimate resultant force (114.6N in the axial direction, 17.1N in the buccal and tongue direction, 23.4N in the near and far directions). Results: 1. The stress distribution patterns of solid and porous titanium implants in different types of bone tissues were similar, i. e. the stress concentration area was mainly located in the cortical bone around the neck of the implant under vertical loading. 2. With the increase of porosity, the area of peak stress value of bone tissue around the implant decreases correspondingly. When the porosity reaches 40%, the area of peak stress value decreases more obviously. Under the same mechanical loading, it was observed that the maximum stress on the bone interface of porous titanium implants was greater than that on solid implants. The maximum stress at the bone interface around the implant under lateral loading is much higher than that under vertical loading. 4. With the increase of the porosity of the implant porous layer, the maximum stress at the bone interface increases; the thicker the porous layer, the larger the diameter of the intermediate pillar, the thicker the porous titanium implant with the same porosity. The maximum stress on the bone interface increases with the change of bone mass in both solid and porous implants. Conclusion: 1. Bone tissue around porous titanium implants was observed under different mechanical loads. The maximum stress of the bone around the implant increases with the increase of the pore structure. The maximum stress of the bone around the implant changes with the change of the bone mass, the lower the bone density, and the bone tissue around the implant bears the stress. The greater the maximum stress, the greater the stress produced by the lateral force on the bone tissue around the implant than the vertical force. 2. The denser the bone, the smaller the occlusal force, the more conducive the porous structure to stress transmission to the surrounding bone tissue than the solid structure, increasing the stress of the bone tissue around the implant to offset the stress shielding. 3. The more loose the bone, the less occlusal force. The greater the force value, the more cautious the use of porous structure implants, strictly control the lateral force and excessive occlusal force to prevent the occurrence of pathological load.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R783.6

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