中文摘要：

目的：观察小鼠切牙机械损伤后成牙本质细胞（OB）的Notch表达及细胞凋亡情况,分析Notch信号与OB细胞凋亡的可能关系。方法：小鼠下颌切牙牙冠远中颈部机械备洞制造牙齿损伤,损伤后1、3、5、7d取材,用免疫组织化学染色方法检测OB细胞Notch1、Notch2表达情况,用TUNEL染色法观察OB细胞凋亡情况。结果：机械损伤可激活OB细胞Notch表达并呈动态变化：损伤后1d,Notch1、Notch2呈阳性表达;损伤后3d,Notch1、Notch2表达最明显,呈强阳性;损伤后5d,Notch1、Notch2仍呈阳性表达;损伤后7d,Notch1、Notch2表达均减弱。对照组OB细胞Notch1、Notch2仅有微弱表达。细胞凋亡检测显示：对照组OB层仅见零星凋亡细胞;损伤组的近损伤区凋亡细胞明显增多。OB细胞凋亡在损伤后1d最多,损伤后3~7d逐渐减少。以上说明：机械损伤导致OB层细胞凋亡和Notch表达激活伴行出现,前者1d最明显,后者3d达高峰。结论：小鼠切牙机械损伤后成牙本质细胞Notch信号表达激活并可能与细胞凋亡调控存在联系。

英文摘要：

Objective：To investigate Notch expression and apoptosis in odontoblasts of mouse incisor after mechanical injury.Methods：Dental mechanical injury model was established through the cavity preparation on the mandibular incisor of mice.The expressions of Notch1 and Notch2in the odontoblasts were observed by immunohistochemical staining,and apoptosis of the odontoblasts was observed by TUNEL staining.Results：The expression of Notch in odontoblasts were activated by mechanical injury and showed a dynamic change.One day after injury,the expressions of Notch1 and Notch2were positive;3days after injury,the expressions of Notch1 and Notch2were significantly increased and were intensively positive;5days after injury,Notch1 and Notch2were still positive;7days after injury,the expressions of Notch1 and Notch2became weak.In control,expressions of Notch1 and Notch2were very weak.Mechanical injury leaded to massive apoptosis in dental pulp.Apoptosis staining in the odontoblasts was obvious 1day after injury,and the apoptotic cells decreased gradually from 3-7days after injury.Few apoptotic odontoblasts were observed in the control group.Concomitant pattern of the cell apoptosis and Notch expression in the odontoblasts were exhibited after mechanical injury of tooth.Conclusion：Dynamic activation of Notch signaling might be connected with apoptosis regulation in odontoblasts after mechanical injury.