Adjunct Professor, Department of Dental Medicine, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain.
Postgraduate student, Department of Dental Medicine, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain.
J Prosthet Dent. 2020 Dec;124(6):720-726. doi: 10.1016/j.prosdent.2019.10.014. Epub 2020 Jan 25.
Implant-supported prostheses may be subject to esthetic, biological, or mechanical complications. Protocols for dealing with these mechanical problems are sparse.
The purpose of this in vitro study was to compare the efficacy of a mechanical system for extracting fractured implant-prosthesis screws with the conventional method.
A total of 60 screws were divided into 2 groups according to their morphology (flat screws with a smooth shaft and threaded apical area and screws with a completely threaded body) and subjected to fatiguing and static load testing until fracture. The specimens were assigned to 3 operators with varying levels of clinical experience (high, medium, low) in extracting fractured screws by using the conventional method (explorer and ultrasound device) and a mechanical method (extractor kit). The extraction event (whether the screw fragment was extracted or not within 10 minutes) was recorded, and the time taken to perform the extraction was measured for each method in relation to screw type, operator experience, and damage to the threads. The influence of screw morphology, extraction method, operator experience, and fracture type on the time needed to extract a screw fragment was assessed with the Mann-Whitney and Kruskal-Wallis tests. Thread damage was compared by using the Fisher's exact test and the Kruskal-Wallis test (α=.05).
The mechanical method was more effective for screw extraction than the conventional method (P=.032). Screw morphology also had a significant influence on extraction, whereby the screw design with apical thread took less time to extract (P=.022). Coronal fractures had a higher probability of extraction than apical fractures (P=.05).
Mechanical extraction is more effective for extracting fractured implant-prosthetic screws, showing a higher probability of extraction than the conventional method. Prosthetic fixing screws with a smooth shaft and threaded apical area are the easiest to extract.
种植体支持的修复体可能会出现美学、生物学或机械方面的并发症。处理这些机械问题的方案很少。
本体外研究的目的是比较一种用于提取断裂的种植体-修复体螺钉的机械系统与传统方法的效果。
总共 60 个螺钉根据其形态（带有平滑轴和螺纹根尖区域的平螺钉和带有全螺纹体的螺钉）分为 2 组，并进行疲劳和静态负载测试，直到断裂。将这些样本分配给 3 位操作人员，他们在提取断裂螺钉方面的临床经验水平不同（高、中、低），分别使用传统方法（探针和超声设备）和机械方法（提取套件）。记录提取事件（在 10 分钟内是否提取出螺钉碎片），并测量每种方法提取螺钉所需的时间，与螺钉类型、操作人员经验和螺纹损坏有关。使用 Mann-Whitney 和 Kruskal-Wallis 检验评估螺钉形态、提取方法、操作人员经验和骨折类型对提取螺钉碎片所需时间的影响。使用 Fisher 确切检验和 Kruskal-Wallis 检验（α=.05）比较螺纹损坏情况。
与传统方法相比，机械方法更有效地提取螺钉（P=.032）。螺钉形态对提取也有显著影响，其中带有根尖螺纹的螺钉设计提取时间更短（P=.022）。冠状骨折比根尖骨折更容易提取（P=.05）。
机械提取更有效地提取断裂的种植体-修复体螺钉，比传统方法具有更高的提取概率。带有平滑轴和螺纹根尖区域的修复体固定螺钉最容易提取。
