三种回转速度设定对涡旋手机在体外根管内扭矩和根尖力的影响。

The effect of three rotational speed settings on torque and apical force with vortex rotary instruments in vitro.

机构信息

Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, 2155 Webster Street, San Francisco, CA 94115, USA.

出版信息

J Endod. 2011 Jun;37(6):860-4. doi: 10.1016/j.joen.2011.01.022. Epub 2011 May 6.

DOI:10.1016/j.joen.2011.01.022

PMID:21787506

Abstract

INTRODUCTION

Both the number of rotations in curved canals and torque are related to fracture resistance of nickel-titanium rotaries via the respective mechanisms of brittle and flexural failure. Increased rotational speed (rotations per minute [RPM]) may lead to higher cutting ability and could overcompensate for increased fatigue. The impact of three RPM settings on peak torque (Nmm) and apically directed force (N) during root canal preparation were investigated in vitro.

METHODS

S-shaped canals in plastic blocks (n = 12/group) were instrumented with Vortex rotaries (Dentsply Tulsa Dental, Tulsa, OK) sizes #15 to 30 with a .04 taper. Rotaries were used in a manufacturer-recommended sequence: #30, 25, and 20 in a crown-down approach progressively deeper into the canal, #15 to the working length, and apical enlargement with sizes 20 and 25 to WL. A total of 216 preparation procedures were performed using a custom testing platform. RPM was set at 200, 400, or 600; automated axial feed mirrored clinical handling, resulting in two in-and-out movements, each to preset insertion depths. Torque and apical force were continuously recorded and peak values statistically contrasted using analysis of variances.

RESULTS

No file fractures were observed in any of the three experimental groups. Peak torques and forces varied by instrument size and were highest at 200 RPM for all sizes; torque and force were reduced by 32% and 48%, respectively, at 400 RPM (P < .001). Increasing RPM to 600 did not result in further reductions. The number of discernible peaks for torque (threshold: 0.3 Nmm) and force (threshold: 0.2 N) significantly decreased from 200 RPM to 400 RPM and did not decrease further with 600 RPM.

CONCLUSIONS

Under the present experimental conditions, rotational speed had a significant impact on preparation with Vortex rotaries, with instruments at 400 RPM generating less torque and force compared with 200 RPM.

摘要

简介

通过脆性和弯曲失效的各自机制，弯曲根管中的旋转次数和扭矩都与镍钛旋转器械的抗折强度有关。增加转速（每分钟转数[RPM]）可能会提高切削能力，并可能弥补疲劳强度的增加。本研究在体外研究了三种 RPM 设置对根管预备过程中峰值扭矩（Nmm）和根尖向力（N）的影响。

方法

在塑料块中的 S 形根管（每组 n = 12）中用 Vortex 旋转器械（登士柏 Tulsa 牙科，塔尔萨，俄克拉荷马州）进行预备，锥度为 0.04，从 15 号到 30 号。旋转器械按制造商推荐的顺序使用：在冠向下法中，从 30 号开始，每次递进深入根管 25 号和 20 号，到根管工作长度，用 20 号和 25 号进行根尖扩大。使用定制测试平台共完成 216 次预备程序。将 RPM 设置为 200、400 或 600；自动轴向进给与临床处理相匹配，导致两次进出运动，每次运动到预设的插入深度。连续记录扭矩和根尖力，使用方差分析对峰值进行统计学对比。

结果

在三个实验组中均未观察到器械折断。各器械尺寸的峰值扭矩和力不同，所有尺寸在 200 RPM 时最高；400 RPM 时扭矩和力分别降低 32%和 48%（P <.001）。增加到 600 RPM 时，扭矩和力并没有进一步降低。扭矩（阈值：0.3 Nmm）和力（阈值：0.2 N）的可分辨峰值数量从 200 RPM 显著减少到 400 RPM，而在 600 RPM 时不再减少。