Department of Prosthodontics and Occlusion, School of Dentistry, University of Oviedo, Oviedo, Spain.
Int J Oral Maxillofac Implants. 2013 May-Jun;28(3):e112-21. doi: 10.11607/jomi.2813.
Three-dimensional finite element analysis was conducted to evaluate and compare the stress distribution in the abutment and retention screw of implant-supported single crowns with platform switching and with a conventional platform under vertical and oblique loading.
Two finite element models were created simulating an osseointegrated implant (4 × 10 mm, platform 4.1 mm) embedded in jawbone. One model simulated a 4-mm-diameter abutment connection (conventional model) and the other represented a 3.8-mm-diameter abutment connection (platform-switched model). A crown with a cobalt-chromium framework and feldspathic porcelain veneering was applied to the titanium abutment. Static vertical and oblique loads were applied to the crown, with a maximum load of 150 N.
In both models, the highest stress values occurred in the abutment during vertical and oblique loading. Nevertheless, the von Mises stresses in the abutment and the retention screw were lower in the platform-switched model than in the conventional model. During axial loading, the abutment and screw supported slightly less stress in the conventional model than in the platform-switched model. Increases in the angle of force application caused a progressive increase in stresses in the abutment and screw in both models. The maximum stress was distributed at the margin and transgingival area of the abutment and on two-thirds of the flat area and the first threads of the retention screw in both models.
Platform switching reduced the stress values on the abutment and retention screw of a single-unit prosthesis during oblique loading. Regardless of whether platform switching was employed, the stress on the abutment and screw gradually increased as the loading direction changed from vertical to 45 degrees oblique. The locations and distributions of stresses were similar in both models.
通过三维有限元分析，评估并比较在垂直和倾斜加载下，种植体支持的单冠修复中平台转换和传统平台的基台和固位螺钉的应力分布。
创建了两个有限元模型，模拟了一个骨整合种植体（4×10mm，平台 4.1mm）植入颌骨。一个模型模拟了 4mm 直径的基台连接（传统模型），另一个代表了 3.8mm 直径的基台连接（平台转换模型）。一个钴铬框架和长石瓷贴面的皇冠被应用于钛基台。对皇冠施加静态垂直和倾斜载荷，最大载荷为 150N。
在两个模型中，垂直和倾斜加载时，基台的最高应力值最大。然而，在平台转换模型中，基台和固位螺钉的 von Mises 应力比传统模型低。在轴向加载时，传统模型中基台和螺钉支撑的应力比平台转换模型略低。力作用角度的增加导致两个模型中基台和螺钉的应力逐渐增加。最大应力分布在基台的边缘和龈下区域，以及两个模型中固位螺钉的三分之二平坦区域和第一个螺纹处。
平台转换减少了单单位修复体在倾斜加载下基台和固位螺钉的应力值。无论是否采用平台转换，随着加载方向从垂直变为 45 度倾斜，基台和螺钉上的应力逐渐增加。两个模型的应力分布位置相似。
