Roy R A, Ahmad M, Crum L A
Applied Physics Laboratory, University of Washington, Seattle 98105.
Int Endod J. 1994 Jul;27(4):197-207. doi: 10.1111/j.1365-2591.1994.tb00254.x.
Ultrasonically driven vibrating files are known to enhance the efficiency of root canal debridement. This paper presents a phenomenological view of the hydrodynamic response of an oscillating ultrasonic file and the relationship between the file response and various physical factors such as file size and curvature, file surface properties, file velocity amplitude, root canal geometry, and the type of irrigant. Relevant hydrodynamic properties include the propensity of a file to produce stable and transient cavitation, steady streaming, and cavitation microstreaming. These relationships were explored by experiment. Sonoluminescence was employed as an indicator of transient cavitation activity and photographic analysis was utilized as a means for detecting steady streaming, microstreaming, and stable cavitation. Measurements failed to indicate any strong correlation between registered driving power and the propensity to produce transient cavitation. Files that were pitted or possessed salient edges were very effective at generating transient cavitation. When observed, transient cavitation activity generally occurred near the tip of the straight file, provided the wall-loading did not inhibit file motion. In all cases studied, steady streaming and stable cavitation were observed to varying degrees, depending on the amount of file to wall contact. Stable cavitation was probably enhanced by the addition of moderate amounts of dissolved gas into the irrigant. Although the imposition of file-wall contact served to inhibit the production of transient cavitation, this action had relatively little effect on the ability of a file to produce a nominal level of streaming, microstreaming, and stable cavitation. The relationship between these hydrodynamic properties and the process of root canal debridement is addressed. Observations suggest that it is not prudent to ascribe enhanced cleaning effects to any one phenomenon, for it is likely that several factors are involved to varying degrees depending on the local conditions of application.
众所周知，超声驱动的振动锉可提高根管清创的效率。本文从现象学角度探讨了振荡超声锉的流体动力学响应，以及锉的响应与各种物理因素之间的关系，这些物理因素包括锉的尺寸和曲率、锉的表面特性、锉的速度幅值、根管几何形状以及冲洗液的类型。相关的流体动力学特性包括锉产生稳定空化和瞬态空化的倾向、稳态流和空化微流。通过实验对这些关系进行了探究。将声致发光用作瞬态空化活动的指标，并利用摄影分析来检测稳态流、微流和稳定空化。测量结果未能表明记录的驱动功率与产生瞬态空化的倾向之间存在任何强相关性。有凹坑或有突出边缘的锉在产生瞬态空化方面非常有效。当观察到时，瞬态空化活动通常发生在直锉的尖端附近，前提是壁负载不会抑制锉的运动。在所研究的所有情况下，均观察到不同程度的稳态流和稳定空化，这取决于锉与壁的接触量。向冲洗液中添加适量的溶解气体可能会增强稳定空化。虽然锉与壁的接触会抑制瞬态空化的产生，但这种作用对锉产生标称水平的流、微流和稳定空化的能力影响相对较小。本文探讨了这些流体动力学特性与根管清创过程之间的关系。观察结果表明，将增强的清洁效果归因于任何一种现象都是不明智的，因为很可能取决于局部应用条件，多种因素在不同程度上都有所涉及。
