Regeneration of trigeminal nerve ending mechanoreceptor function.-As an indication of ideal orthodontic treatment intervention time.

已有研究报道，在咀嚼早期，TMJ机械感受器的成熟被促进，当咀嚼负荷降低时，TMJ机械感受器不能维持其功能。本研究的目的是探讨在生长早期恢复适当的TMJ负荷是否会导致TMJ机械感受器功能的恢复。将99只2周龄雄性Wistar大鼠随机分为两组，分别饲喂颗粒饲料[对照组(n=33)]和液体饲料[实验组(n=66)]。试验组又分为改食组(n=33)和流食组(n=33)，前者从5周起开始饲喂颗粒饲料而不喂流质饲料。分别于5、7、9周记录三叉神经节的TMJ机械感受器活动。测定各组大鼠的放电阈值和最大瞬时放电频率，并与对照组进行比较。比较各实验亚组单个TMJ单位与对照组的放电特性。改变饮食组大鼠TMJ单位的放电特性在7周时基本恢复。综上所述，在生长早期进行适当的TMJ负荷可以恢复TMJ的机械感受器功能。

Previous studies have reported that the maturation of temporomandibular joint(TMJ) mechanoreceptors was promoted in the early masticatory stage and TMJ mechanoreceptors could not sustain their function when masticatory loading was decreased. The purpose of the present study was to investigate whether a resumption of proper TMJ loading during the early growth period could lead to the restoration of TMJ mechanoreceptor function. Ninety-nine 2-week-old male Wistar rats were divided into two groups and feeding was started with either pellets[ control group(n=33)] or liquid diet[ experimental group(n=66)]. The experimental group was further divided into changing-diet(n=33) and liquid-diet(n=33) groups ; the former was fed pellets instead of liquid diet from 5 weeks. TMJ mechanoreceptor activities were recorded from the trigeminal ganglion at 5, 7 and 9 weeks. The firing threshold and maximum instantaneous firing frequency were measured in each group in comparison with the control group. The firing properties of single TMJ units in each experimental subgroup were compared to those in the control group. In the changing-diet group, the firing properties of TMJ units were recovered at 7 weeks. In conclusion, proper TMJ loading during the early growth period can lead to the restoration of TMJ mechanoreceptor function.