Lee Hyeonjong, Jo Minhye, Noh Gunwoo
Department of Prosthodontics, Dental Research Institute, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan, Korea.
School of Mechanical Engineering, Korea University, Seoul, Korea.
Comput Methods Programs Biomed. 2021 Mar;200:105863. doi: 10.1016/j.cmpb.2020.105863. Epub 2020 Nov 22.
Understanding fatigue failure and microgap formation in dental implants, abutments, and screws under various clinical circumstances is clinically meaningful. In this study, these aspects were evaluated based on implant diameter, connection type, and bone density.
Twelve three-dimensional finite element models were constructed by combining two bone densities (low and high), two connection types (bone and tissue levels), and three implant diameters (3.5, 4.0, and 4.5 mm). Each model was composed of cortical and cancellous bone tissues, the nerve canal, and the implant complex. After the screw was preloaded, vertical (100 N) and oblique (200 N) loadings were applied. The relative displacements at the interfaces between implant, abutment, and screw were analyzed. The fatigue lives of the titanium alloy (Ti-6Al-4V) components were calculated through repetitive mastication simulations. Mann-Whitney U and Kruskal-Wallis one-way tests were performed on the 50 highest displacement values of each model.
At the implant/abutment interface, large microgaps were observed under oblique loading in the buccal direction. At the abutment/screw interface, microgap formation increased along the implant diameter under vertical loading but decreased under oblique loading (p < 0.001); the largest microgap formation occurred in the lingual direction. In all cases, the bone-level connection induced larger microgap formation than the tissue-level connections. Moreover, only the bone-level connection models showed fatigue failure, and the minimum fatigue life was observed for the implant diameter of 3.5 mm.
Tissue-level implants possess biomechanical advantages compared to bone-level ones. Two-piece implants with diameters below 3.5 mm should be avoided in the posterior mandibular area.
了解在各种临床情况下牙种植体、基台和螺钉的疲劳失效及微间隙形成具有临床意义。在本研究中，基于种植体直径、连接类型和骨密度对这些方面进行了评估。
通过组合两种骨密度（低和高）、两种连接类型（骨水平和组织水平）以及三种种植体直径（3.5、4.0和4.5毫米）构建了12个三维有限元模型。每个模型由皮质骨和松质骨组织、神经管以及种植体复合体组成。在螺钉预加载后，施加垂直（100 N）和倾斜（200 N）载荷。分析种植体、基台和螺钉之间界面处的相对位移。通过重复咀嚼模拟计算钛合金（Ti-6Al-4V）部件的疲劳寿命。对每个模型的50个最高位移值进行曼-惠特尼U检验和克鲁斯卡尔-沃利斯单向检验。
在种植体/基台界面，在颊侧倾斜加载下观察到较大的微间隙。在基台/螺钉界面，垂直加载下微间隙形成沿种植体直径增加，但倾斜加载下减少（p < 0.001）；最大的微间隙形成发生在舌侧方向。在所有情况下，骨水平连接比组织水平连接诱导更大的微间隙形成。此外，只有骨水平连接模型显示出疲劳失效，并且对于3.5毫米的种植体直径观察到最小的疲劳寿命。
与骨水平种植体相比，组织水平种植体具有生物力学优势。在下颌后部区域应避免使用直径小于3.5毫米的两件式种植体。
