Ahmad M, Roy R A
Department of Conservative Dentistry, University of Malaya, Kuala Lumpur, Malaysia.
Endod Dent Traumatol. 1994 Apr;10(2):71-6. doi: 10.1111/j.1600-9657.1994.tb00063.x.
The incidence of breakage of Piezon-Master ultrasonic K files were evaluated. Three groups of unused files were subjected to three treatments, namely; free vibration in air without irrigation, free vibration in root canal while minimizing contact with the wall of canal in the presence of irrigation and light filing in root canal with free flow of irrigation. Cavitation produced by files in contact and free of contact with a glass surface was examined in order to observe the relationship between cavitation defects and breakage. In addition, the fractured and unfractured files were examined under a scanning electron microscope for the presence of cavitation pits. The results indicated that more files broke in air. In water, a higher incidence of breakage occurred when files were allowed to freely vibrate while no breakage occurred when the files were used in filing. All files generated cavitation which resulted in pitting of their surfaces. However, it was considered unlikely that the pits contributed to fracture. Fatigue cracks which could be the result of the manufacturing process were observed at some of the corners of the cross sections of the fractured files and could be the main contributory factor to fracture.
评估了派尔胜超声K锉的折断发生率。三组未使用的锉进行了三种处理，即：在无冲洗的空气中自由振动、在根管中自由振动同时在有冲洗液的情况下尽量减少与根管壁的接触、在根管中轻锉并保持冲洗液自由流动。检查了锉与玻璃表面接触和不接触时产生的空化现象，以观察空化缺陷与折断之间的关系。此外，对折断和未折断的锉在扫描电子显微镜下检查是否存在空化坑。结果表明，更多的锉在空气中折断。在水中，当锉自由振动时折断发生率较高，而在锉削使用时未发生折断。所有锉都产生了空化现象，导致其表面出现凹坑。然而，认为这些凹坑不太可能导致折断。在折断锉的横截面的一些角部观察到可能是制造过程导致的疲劳裂纹，这可能是折断的主要促成因素。
