Int J Prosthodont. 2023 May;36(2):203-215. doi: 10.11607/ijp.7269. Epub 2023 May 24.
To evaluate the stress distribution in endocrowns and post-and-core crowns used as abutments for a Kennedy Class I removable partial denture constructed with different framework materials.
3D models of a Kennedy Class I mandible were constructed. Cobalt-chromium (Co-Cr) and polyether ether ketone (PEEK) frameworks were simulated for Models 1 and 2, respectively. An endocrown and a fiber post-and-core crown for the mandibular left and right second premolar abutments, respectively, were simulated for both models. Lithium disilicate porcelain was defined for the crowns. A 200-N occlusal force was applied in the vertical and 30-degree oblique directions.
The von Mises stresses were evaluated for the abutments and prostheses, and the principal stresses for the cortical bone under vertical and oblique loading. Endocrowns showed lower stress values than post-and-core crowns in both models. Post-and-core crowns generated the highest stress in Model 2 under vertical loading. The PEEK framework caused higher stress values on the abutments than Co-Cr. Compressive stresses were higher than tensile stresses in cortical bone. The highest compressive stress was observed around the left premolar cortical bone area in Model 1 under oblique loading. Oblique loading caused lower stress values than vertical loading, except for on the minor connectors and cortical bone.
From a biomechanical perspective, endocrowns may be more advantageous than post-and-core crowns when used as abutments for a Kennedy Class I removable partial denture. In addition, Co-Cr frameworks showed more favorable stress distribution on abutments than PEEK frameworks. Int J Prosthodont 2023;36:203-215. doi: 10.11607/ijp.7269.
评估作为 Kennedy 一类可摘局部义齿基牙的内冠和桩核冠的应力分布，这些基牙采用不同的支架材料。
构建了 Kennedy 一类下颌骨的 3D 模型。模型 1 模拟钴铬（Co-Cr）支架，模型 2 模拟聚醚醚酮（PEEK）支架。分别为两个模型的下颌左、右侧第二前磨牙基牙模拟内冠和纤维桩核冠。全瓷冠采用二硅酸锂瓷。在垂直和 30 度斜向方向上分别施加 200N 的牙合力。
评估了基牙和修复体的 von Mises 应力，以及垂直和斜向加载下皮质骨的主应力。与两种模型中的桩核冠相比，内冠的应力值较低。在垂直加载下，模型 2 中的桩核冠产生的应力最高。PEEK 支架在基牙上产生的应力值高于 Co-Cr。皮质骨中的压缩应力高于拉伸应力。在模型 1 斜向加载下，左侧前磨牙皮质骨区域周围观察到最高的压缩应力。斜向加载产生的应力值低于垂直加载，除了在小连接体和皮质骨处。
从生物力学的角度来看，内冠作为 Kennedy 一类可摘局部义齿的基牙可能比桩核冠更具优势。此外，Co-Cr 支架在基牙上的应力分布优于 PEEK 支架。
