Introduction: The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method. Materials and methods: Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm–1 mm, 1 mm–2 mm, 1 mm–4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically. Results: The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm–1 mm mucosa thickness models. The models with 1 mm–2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models. Conclusion: In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.

中文翻译：

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黏膜厚度对单侧负荷下种植体支持的覆盖义齿应力分布的影响：光弹性分析

简介：本研究的目的是使用光弹性应力分析方法评估不同附着高度和黏膜厚度对两种种植体固位下颌覆盖义齿设计在负载下应力分布的影响。材料和方法：用放置在尖牙区域的两个单独植入物制作了六个无牙颌下颌骨的光弹性模型。研究的附件系统是球和定位螺柱附件。球和定位器组都包括三个模型，它们具有不同的残余脊高度，以提供不同的粘膜厚度（1 mm-1 mm、1 mm-2 mm、1 mm-4 mm）。将 135 N 的静态垂直力单侧（每个在右侧，然后在左侧）施加到第一磨牙的中央窝。模型被放置在圆偏光镜的视野中，以观察植入物周围等色条纹的分布和负载下的植入物间区域。监测和记录光弹性应力条纹。结果：球附件组在负载下显示出比定位器组更高的应力值。两种附着系统在受刺激的 1 mm-1 mm 粘膜厚度模型中产生的应力值最低。黏膜厚度为 1 mm-2 mm 的模型显示出比两种附着系统的其他模型更高的应力值。在所有测试模型中，在两个附件系统周围观察到的最高应力值是中等水平。结论：在不同高度黏膜厚度下，定位器附着模型将载荷分布到种植体的另一侧及其周围组织，而球附件没有。无论黏膜厚度和附着类型如何，负载侧的植入物都受到最高应力集中。