Jiang M Y, Wen J, Xu S S, Liu T S, Sun H Q
Department of Prosthodontics, School of Stomatology, Shandong University & Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Jinan 250012, China Wen Jing is working on the Department of Stomatology, Wujiang District First People's Hospital, Suzhou City, Suzhou 215200, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2019 Jan 9;54(1):41-45. doi: 10.3760/cma.j.issn.1002-0098.2019.01.008.
To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method. Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures. Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa). In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.
采用三维有限元分析方法，比较Locator附着体或杆卡附着体支持的四颗种植体下颌覆盖义齿在不同机械载荷下的生物力学特性。建立了两种不同的四颗种植体支持的下颌覆盖义齿模型，分别采用Locator附着体和杆卡附着体（以下简称Locator模型和杆卡模型）。每个模型承受五种不同的机械加载条件：中切牙垂直加载100 N（切牙垂直载荷）、尖牙垂直加载100 N或斜向加载（尖牙垂直或斜向载荷）、下颌第一磨牙垂直或斜向加载100 N（下颌第一磨牙垂直或斜向载荷）。记录上述五种条件下种植体、种植体周围骨和黏膜的应力分布，以评估不同附着体对种植体支持的下颌覆盖义齿生物力学性能的影响。无论加载条件和附着体类型如何，种植体中的应力集中位于种植体颈部，种植体周围骨中的应力集中位于皮质骨。黏膜中的应力值始终远小于种植体和皮质骨中的应力值。无论加载位置（在尖牙或下颌第一磨牙上），侧向加载下种植体周围骨界面处的最大应力远高于垂直加载下的最大应力。在各种加载条件下，Locator模型种植体和皮质骨中的应力（最高von Mises应力值分别为79.5和22.3 MPa）低于杆卡模型（最高von Mises应力值分别为110.3和28.7 MPa），而Locator模型黏膜中的最大压应力（0.198 MPa）略高于杆卡模型（0.137 MPa）。在临床实践中，应尽量减小施加于种植体固位覆盖义齿的侧向力，以避免病理性载荷引起的并发症。在相同加载条件下，采用Locator附着体的覆盖义齿应力分布更分散，更有利于种植体的长期稳定性。
