Nokar Saied, Hajimiragha Habib, Sadighpour Leyla, Mostafavi Azam Sadat
Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
Dent Res J (Isfahan). 2020 Dec 10;17(6):439-446. eCollection 2020 Nov-Dec.
High percentage of biomechanical complications such as screw loosening in dental implants can be related to implant-abutment (I/A) connection properties which affect the behavior of implant assembly against functional loads in the oral cavity. The aims of the present study were to compare the reverse torque values (RTVs) and failure loads of three abutment types with internal Morse taper connection.
In this experimental study, eighteen implants (4.5 mm × 10 mm bone level implants, Implantium, Dentium Co, Seoul, South Korea) were divided into three groups with different abutments: two-piece (TP) abutment, one-piece (OP) abutment, and screw abutment (SA), mounted in stainless-steel blocks according to ISO 14801. After completion the torque/detorque protocol, a compressive load (1 mm/min) was applied at 30° off-axis until failure. Mean reverse torque/tightening torque (RT/TT) values and failure loads were analyzed with one-way ANOVA test and Tukey's honest significant difference (α = 0.05). Failure modes were evaluated by radiography and stereomicroscopy.
RT/TT values in the TP group were lower than those in other groups ( < 0.001). Highest failure loads were observed in SA group ( = 0.002). In radiographic evaluation, all specimens showed deformation in I/A interface.
I/A connections with larger surface areas may lead to higher RTVs (e.g., OP and SA groups). Use of an additional screw and indexed area in TP group did not reduce the bending resistance under static loading.
牙种植体中诸如螺钉松动等生物力学并发症的高发生率可能与种植体-基台（I/A）连接特性有关，这些特性会影响种植体组件在口腔功能负荷下的行为。本研究的目的是比较三种具有内部莫氏锥度连接的基台类型的反向扭矩值（RTVs）和破坏载荷。
在本实验研究中，18颗种植体（4.5毫米×10毫米骨水平种植体，Implantium，韩国首尔登腾公司）被分为三组，每组使用不同的基台：两件式（TP）基台、一体式（OP）基台和螺钉基台（SA），根据ISO 14801安装在不锈钢块中。完成扭矩/解扭矩方案后，以30°偏轴施加压缩载荷（1毫米/分钟）直至破坏。使用单因素方差分析和Tukey诚实显著性差异检验（α = 0.05）分析平均反向扭矩/拧紧扭矩（RT/TT）值和破坏载荷。通过射线照相和立体显微镜评估破坏模式。
TP组的RT/TT值低于其他组（<0.001）。SA组观察到最高的破坏载荷（=0.002）。在射线照相评估中，所有标本在I/A界面均显示变形。
具有较大表面积的I/A连接可能导致更高的RTVs（例如，OP组和SA组）。TP组中额外使用螺钉和索引区域并未降低静态载荷下的抗弯性。
