Objective

To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis.

Methods

Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch (‘long branch’ and ‘short branch’) in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes.

Results

With reference to the ‘long branch’ model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with the exception of the initial condition (1% bone maturation) where the implant is not osseointegrated. By contrast, implant displacements become relevant in the ‘short branch’ model, unless osseointegration level is beyond 20%. The difference between resonance frequency at whole bone maturation and resonance frequency at 1% bone maturation remained lower than 6.5% for all modes, with the exception of the third mode of vibration in the ‘D’ implant where this difference reached 9.7%. With reference to the ‘short branch’, considering the first mode of vibration, 61–68% of the frequency increase was achieved at 10% osseointegration; 72–79% was achieved at 20%; 89–93% was achieved at 50% osseointegration. The pattern of the natural frequency versus the osseointegration level is similar among different modes of vibration.

Significance

Resonance frequencies and their trends towards osseointegration level may differ between implant designs, and in different boundary conditions that are related to implant position inside the mandible; tapered implants are the most sensitive to bone maturation levels, small implants have very little sensitivity. Resonance frequencies are less sensitive to bone maturation level beyond 50%.

中文翻译：

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植入物稳定性评估的模态分析：此方法对不同植入物设计的敏感性

客观的

通过模态3D有限元分析，研究植入物设计对骨整合过程中骨植入系统自然频率变化的影响。

方法

考虑了六个植入物。实体模型是通过逆向工程技术获得的。通过图像分割从CT扫描数据集中建立下颌骨的几何形状。每个植入物实际上都植入了下颌骨。考虑了两种不同的模型，下颌分支的自由长度不同（“长分支”和“短分支”），以便在进行振动分析时模拟边界条件的可变性。对每个模型进行模态分析，并使用各自的振动模式评估前三个共振频率。

结果

关于“长分支”模型，前三种振动模式是整个骨骼振动，其中植入物相对于骨骼的位移最小，但初始条件（骨骼成熟度为1％）除外，在这种情况下，植入物没有骨整合。相比之下，除非骨整合水平超过20％，否则植入物移位在“短分支”模型中变得很重要。对于所有模式，全骨成熟时的共振频率与1％骨成熟时的共振频率之间的差异均低于6.5％，但“ D”型植入物的第三种振动模式除外，该差异达到9.7％。关于“短支路”，考虑到第一种振动模式，在骨积分为10％时，频率增加了61-68％。20％时达到72–79％；骨整合度为50％时达到89-93％。在不同的振动模式之间，固有频率相对于骨整合水平的模式是相似的。

意义

种植体设计之间以及与下颌骨内部种植体位置相关的不同边界条件下，共振频率及其骨整合水平的趋势可能会有所不同。锥形植入物对骨成熟水平最敏感，而小型植入物的敏感性则很小。共振频率对超过50％的骨成熟​​水平不太敏感。