Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan.
Digital Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan.
J Prosthodont Res. 2023 Jul 31;67(3):430-436. doi: 10.2186/jpr.JPR_D_22_00108. Epub 2022 Dec 12.
We investigated and compared the stress distribution within one- and two-piece mini-implants for overdentures with three different attachments (ball, Locator, and magnet) and two different diameters using three-dimensional finite element (3D FE) analysis and a monotonic bending test. The goal was to identify the most beneficial implant attachment system design for mini-implant overdentures with a lower risk of implant fracture.
Twelve 3D FE models simulating a mandible segment with one- and two-piece mini-implants with different attachment systems, diameters, and overdentures were created using three-dimensional computer-aided design (CAD) software. Vertical and oblique forces (45° to the longitudinal axis of the implant) of 100 N were applied to the dentures. The stress distribution was analyzed. A bending test was performed on a mini-implant (Locator, 2.4 mm) using a testing machine to quantify the load at yield stress.
One-piece mini-implants showed lower maximum stress compared to two-piece mini-implants. Among the three designs, the magnet attachment systems showed the maximum stress. The maximum von Mises stress occurred at the neck of the implants, which was surrounded by cortical bone in all models, and under both loading conditions.
Focusing on the attachments and one- and two-piece designs of mini-implant overdentures using CAD models to reduce confounding factors affecting the stress distribution, we concluded that one-piece mini-implants tended to show lower stress compared to two-piece mini-implants. Mini-implant overdentures with Locator and ball attachments demonstrated lower stress within the implants compared to those with magnet attachments under vertical and oblique loading conditions.
本研究通过三维有限元（3D FE）分析和单调弯曲试验，研究和比较了三种不同附着体（球、Locator 和磁铁）和两种不同直径的单、双体迷你种植体支抗覆盖义齿的应力分布，旨在确定一种最有益于降低种植体骨折风险的迷你种植体覆盖义齿的种植体附着体系统设计。
使用三维计算机辅助设计（CAD）软件创建了 12 个模拟带有不同附着体系统、直径和覆盖义齿的单、双体迷你种植体下颌骨段的 3D FE 模型。将 100 N 的垂直和斜向（与种植体长轴成 45°）力施加到义齿上。分析了应力分布。使用试验机对Locator（2.4mm）迷你种植体进行弯曲试验，以量化屈服应力时的载荷。
与双体迷你种植体相比，单体迷你种植体的最大应力较低。在三种设计中，磁铁附着体系统显示出最大的应力。最大 von Mises 应力发生在种植体颈部，所有模型中种植体颈部都被皮质骨包围，且在两种加载条件下均如此。
通过 CAD 模型关注迷你种植体覆盖义齿的附着体和单、双体设计，以减少影响应力分布的混杂因素，我们得出结论，与双体迷你种植体相比，单体迷你种植体的应力往往较低。在垂直和斜向加载条件下，Locator 和球附着体的迷你种植体覆盖义齿的种植体内部的应力低于磁铁附着体的种植体。
