Gulizio Michael P, Agar John R, Kelly J Robert, Taylor Thomas D
Prosthodontics Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, USA.
J Prosthodont. 2005 Mar;14(1):3-11. doi: 10.1111/j.1532-849X.2005.00005.x.
Overdentures supported and retained by endosteal implants depend upon mechanical components to provide retention. Ball attachments are frequently described because of simplicity and low cost, but retentive capacity of these components may be altered by a lack of implant parallelism.
The aim of this in vitro study was to investigate the retention of gold and titanium overdenture attachments when placed on ball abutments positioned off-axis.
Four ball abutments were hand-tightened onto ITI dental implants and placed in an aluminum fixture that allowed positioning of the implants at 0 degrees, 10 degrees, 20 degrees, and 30 degrees from a vertical reference axis. Gold and titanium matrices were then coupled to the ball abutments at various angles and then subjected to pull tests at a rate of 2 mm/second; the peak loads of release (maximum dislodging forces) were recorded and subjected to statistical analyses. A balanced and randomized factorial experimental design testing procedure was implemented.
Statistically significant differences in retention of gold matrices were noted when ball abutments were positioned at 20 degrees and 30 degrees , but not at 0 degrees and 10 degrees. Statistically significant differences were noted among the titanium matrices employed for the testing procedure, as well as for the 4 ball abutments tested. Angle was not a factor affecting retention for titanium matrices.
(1) The gold matrices employed for the testing procedures exhibited consistent values in retention compared to titanium matrices, which exhibited large variability in retention. (2) Angle had an effect upon the retention of gold matrices, but not for titanium matrices.
由骨内种植体支持和固位的覆盖义齿依靠机械部件来提供固位。球帽附着体因其简单性和低成本而经常被提及，但这些部件的固位能力可能会因种植体缺乏平行性而改变。
本体外研究的目的是调查金质和钛质覆盖义齿附着体放置在偏轴球基台上时的固位情况。
将四个球基台手动拧紧到ITI牙科种植体上，并放置在一个铝制固定装置中，该装置允许种植体相对于垂直参考轴分别处于0度、10度、20度和30度位置。然后将金质和钛质基体以不同角度连接到球基台上，接着以2毫米/秒的速度进行拉伸测试；记录释放的峰值负荷（最大脱位力）并进行统计分析。实施了平衡随机析因实验设计测试程序。
当球基台处于20度和30度位置时，金质基体的固位在统计学上有显著差异，但在0度和10度位置时没有。测试过程中使用的钛质基体之间以及所测试的4个球基台之间在统计学上有显著差异。角度不是影响钛质基体固位的因素。
（1）测试过程中使用的金质基体在固位方面表现出一致的值，而钛质基体在固位方面表现出很大的变异性。（2）角度对金质基体的固位有影响，但对钛质基体没有影响。
