Sato Y, Tsuga K, Abe Y, Asahara S, Akagawa Y
Department of Removable Prosthodontics, Hiroshima University, Faculty of Dentistry, Hiroshima, Japan.
J Oral Rehabil. 2001 May;28(5):413-7. doi: 10.1046/j.1365-2842.2001.00673.x.
An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on preferable shape as determined by biomechanics. This study aimed (1) to investigate, by finite element analysis (FEA), the dimensions and stress of I-bar clasps having the same stiffness, and (2) to estimate a mechanically preferable clasp design. Three-dimensional FEA models of I-bar clasps were created with vertical and horizontal straight sections connected by a curved section characterized by six parameters: thickness of the clasp tip, width of the clasp tip, radius of the curvature, horizontal distance between the base and the vertical axis, vertical dimension between the tip and the horizontal axis, and taper (change of width per unit length along the axis). Stress was calculated with a concentrated load of 5 N applied 2 mm from the tip of the clasp in the buccal direction. A thinner and wider clasp having an taper of 0.020-0.023 and radius of curvature of 2.75-3.00 showed less stress. The results suggest that such a shape might be the preferable I-bar clasp shape as biomechanical viewpoint.
I 型杆卡环是远中游离可摘局部义齿最常用的直接固位体之一。然而，关于由生物力学决定的最佳形状，目前尚无足够的信息。本研究旨在：（1）通过有限元分析（FEA）研究具有相同刚度的 I 型杆卡环的尺寸和应力；（2）评估机械性能上更优的卡环设计。创建了 I 型杆卡环的三维有限元分析模型，其垂直和水平直段由一个弯曲段连接，该弯曲段由六个参数表征：卡环尖端厚度、卡环尖端宽度、曲率半径、基部与垂直轴之间的水平距离、尖端与水平轴之间的垂直尺寸以及锥度（沿轴每单位长度宽度的变化）。在距卡环尖端颊侧 2 mm 处施加 5 N 的集中载荷计算应力。锥度为 0.020 - 0.023 且曲率半径为 2.75 - 3.00 的较薄且较宽的卡环应力较小。结果表明，从生物力学角度来看，这种形状可能是更优的 I 型杆卡环形状。
