Postdoctoral Research Fellow, Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Piracicaba, Brazil.
Doctoral student, Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Piracicaba, Brazil.
J Prosthet Dent. 2018 Sep;120(3):421-430. doi: 10.1016/j.prosdent.2017.12.012. Epub 2018 Apr 25.
The use of single or mini dental implants to retain mandibular overdentures is still questionable.
The purpose of this finite element analysis (FEA) study was to investigate the biomechanical behavior of 2- and single-implant-retained mandibular overdentures with conventional or mini implants.
Four 3-dimensional (3D) finite element models were constructed with the following designs of mandibular overdentures: 2 (group 2-C) and single (group 1-C) conventional external hexagon implants with ball or O-ring attachment and 2 (group 2-M) and single (group 1-M) 1-piece mini implants. A 150-N axial load was applied bilaterally and simultaneously on the first molar. Overdenture displacement, von Mises equivalent stress (implants and/or prosthetic components), and maximum principal stresses (peri-implant bone) were recorded numerically and then color-coded and compared among the groups.
The overdenture displacement (in mm) was higher for the 1-M (0.16) and 2-M (0.17) groups when compared with 1-C (0.09) and 2-C (0.08). Irrespective of the type of implant, the single-implant groups presented higher values of stress (in MPa) on the implants than did the 2-implant groups (1-C=52.53; 1-M=2.95; 2-C=34.66; 2-M=2.37), ball attachment (1-C=201.33; 2-C=159.06), housing or O-ring (1-C=125.01; 1-M=1.96; 2-C=88.84; 2-M=1.27), and peri-implant cortical bone (1-C=19.37; 1-M=1.47; 2-C=15.70; 2-M=1.06). The mini implant overdentures presented lower stress values on the implants, housing or O-ring, and peri-implant bone than did the conventional implant overdentures, regardless of the number of implants.
The 2-implant-retained overdentures exhibited lower stresses than the single- implant-retained overdentures, irrespective of the type of implant. The mini implants demonstrated higher overdenture displacement and lower stresses than did conventional implant overdentures for single- and 2-implant-retained overdentures.
使用单个或迷你牙种植体来保留下颌覆盖义齿仍然存在疑问。
本有限元分析（FEA）研究的目的是研究传统或迷你种植体固位的下颌覆盖义齿的生物力学行为。
构建了四个 3 维（3D）有限元模型，下颌覆盖义齿设计如下：2 个（组 2-C）和 1 个（组 1-C）传统外六角种植体，带有球或 O 型环附着体，2 个（组 2-M）和 1 个（组 1-M）1 件迷你种植体。在第一磨牙上双侧同时施加 150-N 的轴向载荷。数值记录了覆盖义齿的位移、von Mises 等效应力（种植体和/或修复体部件）和最大主应力（种植体周围骨），然后对各组进行颜色编码和比较。
与 1-C（0.09）和 2-C（0.08）组相比，1-M（0.16）和 2-M（0.17）组的覆盖义齿位移（mm）更高。无论种植体类型如何，单种植体组的种植体上的应力（MPa）值均高于双种植体组（1-C=52.53；1-M=2.95；2-C=34.66；2-M=2.37）、球附着体（1-C=201.33；2-C=159.06）、外壳或 O 型环（1-C=125.01；1-M=1.96；2-C=88.84；2-M=1.27）和种植体周围皮质骨（1-C=19.37；1-M=1.47；2-C=15.70；2-M=1.06）。与传统种植体覆盖义齿相比，迷你种植体覆盖义齿的种植体、外壳或 O 型环和种植体周围骨的应力值较低，无论种植体数量如何。
无论种植体类型如何，双种植体固位的覆盖义齿的应力均低于单种植体固位的覆盖义齿。迷你种植体在单种植体和双种植体固位的覆盖义齿中表现出较高的覆盖义齿位移和较低的应力。
