Li Ruyi, Wu Zhanglin, Chen Song, Li Xiang, Wan Qianbing, Xie Guo, Pei Xibo
Graduate student, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
Graduate student, State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University, Chengdu, PR China.
J Prosthet Dent. 2023 Mar;129(3):447.e1-447.e10. doi: 10.1016/j.prosdent.2023.01.005. Epub 2023 Feb 1.
The clinical application of short implants has been increasing. However, studies on the marginal bone loss of short implants are sparse, and clinicians often choose short implants based on their own experience rather than on scientific information.
The purpose of this finite element analysis study was to evaluate the microstrain-stress distribution in the peri-implant bone and implant components for 4 types of short implants at different placement depths of platform switching.
By using short implants as prototypes, 4 short implant models were 1:1 modeled. The diameter and length of the implants were 5×5, 5×6, 6×5, and 6×6 mm. The restoration was identical for all implants. Three different depths of implant platform switching were set: equicrestal, 0.5-mm subcrestal, and 1-mm subcrestal. The models were then assembled and assigned an occlusal force of 200 N (vertical or 30-degree oblique). A finite element analysis was carried out to evaluate the maximum equivalent elastic strain and von Mises stress in the bone and the stress distribution in the implant components.
The 5×5 implant group showed the largest intraosseous strain (21.921×10 με). A 1-mm increase in implant diameter resulted in a 17.1% to 37.4% reduction in maximum intraosseous strain when loaded with oblique forces. The strain in the bone tended to be much smaller than the placement depth at the equicrestal and 0.5-mm subcrestal positions than that at the 1-mm subcrestal position, especially under oblique force loading, with an increase of approximately 37.4% to 81.8%. In addition, when the cortical bone thickness was less than 4 mm, 5×6 implants caused significantly higher intraosseous stresses than 6×6 implants.
Large implant diameters, rather than long implants, led to reduced intraosseous strain, especially under oblique loading. Regarding the implant platform switching depth, the short implant showed small intraosseous strains when the platform switching depth was equicrestal or 0.5-mm subcrestal.
短种植体的临床应用一直在增加。然而，关于短种植体边缘骨吸收的研究较少，临床医生通常根据自身经验而非科学信息来选择短种植体。
本有限元分析研究的目的是评估4种类型的短种植体在不同平台转换植入深度时种植体周围骨组织和种植体部件中的微应变 - 应力分布。
以短种植体为原型，按1:1比例构建4个短种植体模型。种植体的直径和长度分别为5×5、5×6、6×5和6×6 mm。所有种植体的修复体均相同。设置三种不同的种植体平台转换深度：平齐龈缘、龈下0.5 mm和龈下1 mm。然后组装模型并施加200 N的咬合力（垂直或30度斜向）。进行有限元分析以评估骨组织中的最大等效弹性应变和von Mises应力以及种植体部件中的应力分布。
5×5种植体组显示出最大的骨内应变（21.921×10 με）。当施加斜向力时，种植体直径增加1 mm会导致最大骨内应变降低17.1%至37.4%。在平齐龈缘和龈下0.5 mm位置，骨内应变往往比龈下1 mm位置小得多，尤其是在斜向力加载下，增加幅度约为37.4%至81.8%。此外，当皮质骨厚度小于4 mm时，5×6种植体引起的骨内应力显著高于6×6种植体。
较大的种植体直径而非较长的种植体可降低骨内应变，尤其是在斜向加载时。关于种植体平台转换深度，当平台转换深度为平齐龈缘或龈下0.5 mm时，短种植体显示出较小的骨内应变。
