中文摘要：

目的：观察低强度脉冲超声（low intensity pulsed ultrasound,LIPUS）对牙本质牙髓复合体损伤修复模型中TGF-β1/Smads信号通路的影响。方法：25只Sprague-Dawley大鼠随机选择5只大鼠作为空白对照组,不予任何处理。剩余20只于双侧上颌第一磨牙采用改良备洞法备洞,建立牙本质牙髓损伤修复模型,右侧为LIPUS组,予以LIPUS辐照（强度为30 m W/cm^2,频率为1.5 MHz,调制信号波宽为200μs,重复率为1 k Hz,20 min/d）;左侧为备洞组,予以超声假照处理。分别在辐照1,3,5,7,14 d后处死大鼠,运用免疫组织化学法及图像分析技术检测TGF-β1,Smad 2和3在牙髓组织中的动态表达和定位情况。结果：TGF-β1,Smad 2,3蛋白在正常牙髓组织中均呈弱阳性表达,而在牙本质损伤后出现不同程度的表达增加。备洞组TGF-β1蛋白表达在1 d时增加,在5 d时TGF-β1表达最强,在14 d时表达减弱接近正常水平;与备洞组相比,LIPUS组在3和5 d时表达明显升高（均P〈0.05）。Smad 2,3在LIPUS组及备洞组牙髓中表达均呈现逐步升高的基本变化,其中LIPUS组升高更明显（P〈0.05）。结论：TGF-β1/Smad 2,3信号通路可能参与了牙本质损伤的修复过程,LIPUS在牙本质损伤修复早期可上调TGF-β1,Smad 2,3的表达,可能参与并促进了牙本质牙髓复合体的损伤修复过程。

英文摘要：

Objective： To explore the effect of low intensity pulsed ultrasound （LIPUS） on TGF-β1/Smad 2,3 signal pathway during the dentin injury and repair. Methods： Among 25 Sprague-Dawley rats, 5 rats served as a blank control group without treatment. The remaining 20 rats received modified caries preparation inbilateral maxillary first molars to establish a model of dentin-pulp injury and repair. The right maxillary first molars served as a LIPUS groupj which received LIPUS irradiation （frequency： 1.5 MHz, pulse width： 200 μs, pulse repetition frequency： 1 kHz, spatial averaged temporal averaged intensity： 30 mW/cm2, 20 min/d）, and the left maxillary first molars served as a cavity-prepared group, which received fake LIPUS irradiation. The rats were sacrificed at 1, 3, 5, 7 and 14 days after LIPUS irradiation. Immunohistochemical staining and Image-pro plus 6.0 were applied to detect the expression and distribution of transforming growth factor-beta1 （TGF-β1） and small mothers against decapentaplegic 2/3（Smad 2 and Smad 3）. Results： Immunohistochemical staining showed that the expression of TGF-β1 and Smad 2, 3 were low innormal pulp, but they were increased in different degree after dentin injury. The result of image analysis showed that the expression of TGF-β1 in the cavity-prepared group gradually increased at the first day and peaked at day 5, and then it returned to normal level at day 14. However, the expression of TGF-β1 in the LIPUS group were significantly higher than that in the cavity-prepared group at day 3 and 5 （both P〈0.05）. The expressions of Smad 2,3 in both the LIPUS group and the cavity-prepared group were consistently increased all the way, but the expressions in the LIPUS group were higher compared with that in the cavity-prepared group （P〈0.05）. Conclusion： The TGF-β1/Smad 2, 3 signal pathway can be activated during the dentin injury and repair. LIPUS can up-regulate the expression of TGF-β1 and Smad 2, 3 in the early period, which may take part