反复取戴对磁性附着体固位力和磁通量的影响

Effect of repeated refitting on retentive force and magnetic flux of a magnetic attachment

目的研究反复取戴对磁性附着体固位力和磁通量的影响及其相关性。方法以5对磁性附着体为研究对象,模拟临床义齿取戴的拉脱—复位运动,在取戴前,取戴2 500、5 000次和10 000次后对磁性附着体的固位力进行测量;在磁体和衔铁精确对位组成标准的闭合磁路的前提下,分别选取3个位点(磁体上表面P1、衔铁下表面P2和侧方P3)进行磁通量的测定。结果 5对磁性附着体在取戴前的固位力为(3.361±0.137)N;反复取戴2 500、5 000次和10 000次后固位力分别下降到(3.109±0.160)、(2.666±0.195)和(2.224±0.231)N。反复取戴前后3个位点的磁通量均有所增加,但其差异无统计学意义,同时固位力和磁通量之间呈线性变化趋势。结论反复取戴磁性附着体会导致其固位力下降,而对磁通量没有显著的影响。

Objective This study aims to evaluate the retentive force and magnetic fl ux of magnetic attachments after repeated insertion–removal cycles. The correlation of retentive force and magnetic fl ux was also observed. Methods A Magfi t EX600W（n=5） was selected as retentive device for this study. The retentive force of the magnetic attachments after 2 500, 5 000, and 10 000 times of insertion–removal cycles was obtained through a universal testing machine. Magnetic fluxes at three positions（P1, upper surface of the magnet; P2, lower surface of the keeper; and P3, lateral side of the magnetic attachment set） were measured using a Gauss meter. Results The initial retentive force of the Magfi t EX600W attachment was（3.361±0.137） N. The retentive force significantly decreased to（3.109±0.160） N,（2.666±0.195） N, and（2.224±0.231） N after 2 500, 5 000, and 10 000 refitting cycles, respectively. However, no significant difference was observed among the increased magnetic fl ux at the three positions after refi tting cycles. Moreover, the retentive force and maximum magnetic fl ux leakage showed strong negative correlation. Conclusion The retentive force decreased because of the refi tting cycles. However, insertion–removal cycles had no signifi cant effect on magnetic fl ux.