Department of Maxillofacial Surgery, Medical University of Lodz, Gen. J. Haller pl 1st, 90-647, Lodz, Poland.
Clin Oral Investig. 2019 Nov;23(11):4059-4066. doi: 10.1007/s00784-019-02842-y. Epub 2019 Mar 20.
Compression screws that can fix a fracture of the condylar head of the mandible are available. Although typical titanium lag screws are generally used, a series of headless screws have been designed for this purpose. The "headless" advantage derived from the complete submergence of the screw in the bone after fixation is the lack of irritation of the lateral ligament of the temporo-mandibular joint by the screw head. The aim of this study is to compare the compression force of typically used lag screws with that of newly developed headless compression screws.
This study tested five types of screws with a 14-mm length: 10 2.0-mm lag screws and 40 headless screws (four groups of equal size: 1.5-mm H screws, 1.8-mm H screws, 2.0-mm H screws, and 1.8-mm W screws). Two cuboid blocks of standardized polyurethane foam were fixed by one screw. The maximal compression force (F in N) and torque at maximal compression force (T in Ncm) were tested according to the guidelines of the American Society for Testing and Materials (ASTM F1839-08).
The test results were as follows: 2.0-mm lag screw: F = 211.5 ± 20.7 and T = 21.1 ± 1.6; 1.5-mm H screw: F = 47.2 ± 5.6 and T = 18.2 ± 1.1; 1.8-mm H screw: F = 95.5 ± 9.8 and T = 18.2 ± 1.1; 2.0-mm H screw: F = 145.1 ± 18.4 and T = 25.5 ± 1.5; and 1.8-mm W screw: F = 180.5 ± 8.7 and T = 26.4 ± 2.8. Each type of screw significantly differed from one another as far as compression forces (F) were considered (p < 0.05): the best is the lag screw contrary to the thinnest H screw which is the worst one. For all tested screws, the compression force depended on the torque (S curve relationship was revealed, p < 0.05) and screw diameter (a larger diameter yielded greater compression, p < 0.05).
The 8-mm headless screws featured only a small loss of compression ability compared to the titanium lag screws.
Headless screws are mechanically attractive fixation materials for condylar head fracture treatment.
有可用于固定下颌骨髁突头骨折的加压螺钉。尽管通常使用典型的钛制拉力螺钉，但为此目的已设计了一系列无头螺钉。“无头”的优势源自固定后螺钉完全淹没在骨中，螺钉头不会刺激颞下颌关节的外侧韧带。本研究的目的是比较常用的拉力螺钉与新开发的无头加压螺钉的压缩力。
本研究测试了五种长度为 14mm 的螺钉：10 个 2.0mm 的拉力螺钉和 40 个无头螺钉（四组大小相等：1.5mm H 螺钉、1.8mm H 螺钉、2.0mm H 螺钉和 1.8mm W 螺钉）。用一个螺钉固定两个标准化的聚氨脂泡沫立方块。根据美国材料试验协会（ASTM F1839-08）的指南，测试最大压缩力（F，单位为 N）和最大压缩力时的扭矩（T，单位为 Ncm）。
测试结果如下：2.0mm 拉力螺钉：F=211.5±20.7，T=21.1±1.6；1.5mm H 螺钉：F=47.2±5.6，T=18.2±1.1；1.8mm H 螺钉：F=95.5±9.8，T=18.2±1.1；2.0mm H 螺钉：F=145.1±18.4，T=25.5±1.5；1.8mm W 螺钉：F=180.5±8.7，T=26.4±2.8。就压缩力（F）而言，每种类型的螺钉均明显不同（p<0.05）：最好的是拉力螺钉，而最细的 H 螺钉最差。对于所有测试的螺钉，压缩力取决于扭矩（揭示了 S 曲线关系，p<0.05）和螺钉直径（较大的直径会产生更大的压缩力，p<0.05）。
8mm 无头螺钉的压缩能力仅略有损失，与钛制拉力螺钉相比。
无头螺钉是治疗髁突头骨折的机械吸引力固定材料。
