Bumbalek Michal, Joska Zdenek, Pokorny Zdenek, Sedlak Josef, Majerik Jozef, Neumann Vlastimil, Klima Karel
First Faculty of Medicine, Charles University Prague, 12108 Prague, Czech Republic.
Faculty of Military Technology, University of Defence, 66210 Brno, Czech Republic.
Materials (Basel). 2021 Apr 23;14(9):2155. doi: 10.3390/ma14092155.
This study investigated the possibility of nitride NiTi instruments using low-temperature plasma nitriding technology in a standard industrial device. Changes in the properties and fatigue life of used NiTi instruments before and after low-temperature nitriding application were investigated and compared. Nontreated and two series of plasma-nitrided NiTi instruments, designed by Mtwo company with tip sizes of 10/.04 taper, 15/.05 taper, and 20/.06 taper, were experimentally tested in this study. All these instruments were used and discarded from clinical use. The instruments were tested in an artificial canal made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature, and a radius of curvature of 3 mm. A low-temperature plasma nitriding process was used for the surface treatment of dental files using two different processes: 550 °C for 20 h, and 470 °C for 4 h. The results proved that it is possible to nitride dental instruments made of NiTi with a low-temperature plasma nitriding process. Promising results were achieved in trial testing by NiTi instruments nitrided at a higher temperature. Plasma-nitrided files were found to have, in some cases, significantly higher values than nontreated files in terms of fatigue life. The results showed that the nitriding process offers promising possibilities for suitably modified surface properties and quality of surface layer of NiTi instruments. Within the limitations of the present study, the cyclic fatigue life of plasma-nitrided NiTi dental files can be increased using this surface technology.
本研究调查了在标准工业设备中使用低温等离子体渗氮技术处理氮化物镍钛器械的可能性。研究并比较了低温渗氮处理前后使用过的镍钛器械的性能和疲劳寿命变化。本研究对未处理的以及由Mtwo公司设计的两种系列的经等离子体渗氮处理的镍钛器械进行了实验测试，其尖端尺寸分别为10/.04锥度、15/.05锥度和20/.06锥度。所有这些器械均已在临床使用后被丢弃。这些器械在由不锈钢制成的内径为1.5毫米、曲率角为60°且曲率半径为3毫米的人工根管中进行测试。采用低温等离子体渗氮工艺对牙科锉进行表面处理，使用两种不同的工艺：550°C处理20小时和470°C处理4小时。结果证明，采用低温等离子体渗氮工艺对由镍钛制成的牙科器械进行渗氮处理是可行的。在较高温度下渗氮处理的镍钛器械在试验测试中取得了良好的结果。发现经等离子体渗氮处理的锉在某些情况下，就疲劳寿命而言，其值明显高于未处理的锉。结果表明，渗氮工艺为适当改变镍钛器械的表面性能和表面层质量提供了有前景的可能性。在本研究的局限性范围内，使用这种表面技术可以提高经等离子体渗氮处理的镍钛牙科锉的循环疲劳寿命。
