Prosthodontic department, Faculty of Dentistry, University of Tanta, Egypt.
Prosthodontic department, Faculty of Dentistry, University of Tanta, Egypt.
Dent Mater. 2019 Nov;35(11):e265-e271. doi: 10.1016/j.dental.2019.07.026. Epub 2019 Aug 16.
The purpose of this in-vitro study was to evaluate the screw loosening of two different forms of implant abutment connection designs, and two implant diameters by measuring removal torque value (RTV) before and after cyclic loading.
Twenty implant fixtures were divided equally into 2 groups (N=10): group I fixture with conical hybrid connection (CH), and group II fixture with internal hex connection (IH). Each group was divided equally into two subgroups according to implant diameters: subgroup A (3.3mm), and subgroup B (4.2mm). Each fixture was vertically placed in the center of an acrylic resin block. The samples were fixed to the jig, and an implant abutment connected it with a 20 Ncm tightening torque. The samples were subjected to eccentric cyclic loading (at a distance of 5mm) away from center of abutment at 100,000 cycles. A digital torque gauge was used to evaluate screw loosening by measuring RTVs in (Ncm) before and after cyclic loading. The removal torque loss ratio before and after cyclic loading and the removal torque loss ratio between before and after cyclic loading were calculated and analyzed using the SPSS statistical analysis.
For GI the initial removal torque loss ratio measurement was (14.45±3.18) and decreased significantly after loading, it was (11.47±3.64). For GII the initial removal torque loss ratio measurement was (20.47±4.99) and increased significantly after loading, being (35.35±4.26). There is no significant effect upon screw loosening for two implant diameters.
Within the limitations of this study, the results suggested that conical hybrid connections showed a better screw stability than an internal hex connection. Therefore, the use of conical implants can be promoted as they have better screw stability compared to other systems.
本体外研究的目的是通过测量循环加载前后的拧紧扭矩值（RTV）来评估两种不同形式的种植体基台连接设计和两种种植体直径的螺钉松动情况。
将 20 个种植体夹具平均分为 2 组（N=10）：组 I 夹具采用锥形混合连接（CH），组 II 夹具采用内六角连接（IH）。每组根据种植体直径平均分为两个亚组：亚组 A（3.3mm）和亚组 B（4.2mm）。每个夹具垂直放置在丙烯酸树脂块的中心。将样本固定在夹具上，用 20 Ncm 的拧紧扭矩连接种植体基台。将样本置于偏心循环加载（距基台中心 5mm 处），100,000 次循环。使用数字扭矩计通过测量循环加载前后的 RTV 来评估螺钉松动情况。使用 SPSS 统计分析计算并分析循环加载前后的拧紧扭矩损失比和循环加载前后的拧紧扭矩损失比。
对于 GI，初始拧紧扭矩损失比测量值为（14.45±3.18），加载后显著下降，为（11.47±3.64）。对于 GII，初始拧紧扭矩损失比测量值为（20.47±4.99），加载后显著增加，为（35.35±4.26）。两种种植体直径对螺钉松动没有显著影响。
在本研究的限制范围内，结果表明锥形混合连接比内六角连接具有更好的螺钉稳定性。因此，与其他系统相比，锥形种植体具有更好的螺钉稳定性，因此可以推广使用。
