【作者】 王晓洁；

【导师】 陈继镛；

【作者基本信息】 四川大学 ， 生物医学工程， 2005， 硕士

【摘要】 种植义齿以其特有的优越性能赢得了广泛的认可,但是人们依然在深入研究影响牙种植成功的各个因素,进一步延长种植义齿的使用寿命,更好的服务于缺失牙患者。圆柱状、螺纹状和台阶状等种植体形态是目前临床应用最广泛的牙种植体形态,被广大医生和缺牙患者所接受。另一方面,由于人体下颌骨复杂多样,机体素质、合力大小、牙体缺失原因等许多因素都会影响缺失牙体后下颌骨的吸收速度和吸收程度,不同患者颌骨形态和质量差别很大。所以,临床选用种植体具有一定的难度。采用三维有限元方法分析种植体的生物力学性能是一种便利、快捷、可靠的理论分析方法,相对实验应力分析更加简单易行、经济快速,应用于牙种植体的研究已经有三十年的历史,取得了一些重要的结果。但是分析结果的有效性和可靠性是建立在精确模型的基础上,随着计算机技术的发展,基于人体下颌骨CT数据建立精确模型已成为可能,故成为当前的研究热点。除了生物力学因素,种植体穿龈段的生物性封闭也是目前研究的重点之一,对各种影响因素的研究结论也各不相同,其中种植方式(埋入式和非埋入式)的选用是临床上颇有争议、亟待解决的问题之一;如何尽快尽早的达到生物性封闭,如何更有利于牙种植体的封闭也是关注的对象,尤其是随着对牙龈组织研究的深入,胶原对种植体周围软、硬组织愈合的生物辅助性也引起人们重视。 根据上述情况,本文着重研究以下四个方面:更多还原

【Abstract】 Dental implants have won people applause with their characteristic advantages, but there still are many things to do.FEA is a convenient and practical method to investigate biomechanics of dental implants. The dependability and authenticity of results depend on the veracity of the FEA model. Three-dimensional (3D) finite element models of the natural mandible bone with cylindrical implants was constructed by a 3D software Pro/Engineering2001 and a finite element analysis (FEA) software ANSYS8.0, based on computed tomography (CT) scan data of a woman. Through comparing the Von Mises stresses distribution of real model to symmetrical model, a conclusion could be made that the two models were significantly different from each other in the stress distributions and real model more effectively showed the biomechanical characterization of dental implants.To obtain biomechanical matching, it is very important to choose anappropriate shape of dental implant according to the bone density. Based on the real model, the Von Mises stresses inside different bone around implants were calculated to investigate the influence of different shapes of implants. The results showed that the neck could cause high stress concentration and it was the weak part of the implant. Oblique loads could cause higher stress concentration in bone than vertical load and should be reduced. For the same load and bone density conditions, cylindrical implant with lowest peak stress is most favorable to cutting down the cervical bone loss; for screw implant, advantages of thread broaden implant utilize. On the other hand, higher local stress taken place at the protrude apex of thread and lower local stress at the concaved apex of thread are dangerous for longer-term utility of implant; the stepped implant is favorable to promote bone growth in lower region around fixture if the higher local stress there within an appropriate range. For the same implant the mandible bone with high density is beneficial to stress distribution. According to the results of FEA, the dense of the mandible bone and shape of implant were very important to the success of implantation. The optimized designed implant should be cylinder. But, in fact, it is necessary to consider all kinds of factors when choosing an implant in clinic.Many studies documented that the method of implantation was of decisive importance for the mucosal attachment that formed. 3 beagle dogs were included in this study. Three non-submerged implants and three submerged implants were installed in each mandibular quadrant after extracting teeth. The animals were sacrificed and perfused with a fixative after 20, 40 and 60 days, respectively. The mandibles were removed and each implant region was dissected and embedded in PMMA. Sections were stained in toluidine blue and basic fuchsin and subjected to histological examination. The findings from the analysis demonstrated that the method of implantation did not influence the quality of the attachment that occurred between the periimplant mucosa and the implant. Everyone case allowed the formation of a mucosal attachment that includes one epithelial and one connective tissue portion. Osseointegration can be obtained in all implant-bone interfaces.It used to be thought that the smooth abutment portion of the implant was necessary for successful biological sealing. With the same animal experiments, three types of transmucosal segment were investigated: "HA coating segment", and two "Collage-HA coating segment". From the clinical index and Light micrographs, a conclusion can be made that the rough surface in the transmucosal portion of the implant still achieves biological sealing. On the other hand, the common boundary between new bone and connection tissue for "collage-HA coating segment" is lower than that of two others. It was suggested that HA can form soft tissue attachment to implants though the surface of HA coating is rough. Another, collage will promote bone up-growth and it is possible to form "bone-fiber-bone" between implant and soft tissue.更多还原