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目的比较Notch2在人年轻恒牙和成熟恒牙的牙髓以及年轻恒牙牙乳头组织中的raRNA和蛋白表达情况，探讨Notch2与牙髓牙本质复合体发育之间的关系。方法收集2008年7月至2010年8月中国医科大学口腔医学院口腔颌面外科门诊因正畸需要而拔除的健康前磨牙48颗（年轻恒牙和成熟恒牙各24颗），拔除后立即分离取出牙髓和年轻恒牙的牙乳头组织。分为3组：第1组为年轻恒牙的牙乳头组织；第2组为年轻恒牙的牙髓组织；第3组为成熟恒牙的牙髓组织。分别用RT-PCR和Westernblot技术检测Notch2的mRNA和蛋白表达，以β-actin为内参照，用图像分析软件（MetaMorph）对阳性条带进行灰度值测定。结果在年轻恒牙的牙乳头和牙髓组织以及成熟恒牙的牙髓组织中均可检测到Notch2的表达；Notch2在年轻恒牙牙髓中的mRNA和蛋白表达强于其在牙乳头以及成熟恒牙牙髓中的表达（P〈0．05）。结论Notch2不仅在年轻恒牙的牙乳头和牙髓组织，而且在成熟恒牙的牙髓组织中均有不同程度的表达，提示Notch2在牙髓牙本质复合体发育过程中可能发挥重要作用。

Expression of Notch2 in the dental papilla and dental pulp tissues of human permanent t,eeth

Objective In order to explore the possible relationship between Notch2 and the development of pulp-dentin complex, the expression of Notch2 in dental papilla and dental pulp of human immature permanent tooth as well as dental pulp of mature permanent tooth were compared at both mRNA and protein levels. Methods A total of 48 intact premolars （consisting of 24 immature permanent teeth and 24 mature permanent teeth）were collected from individuals undergoing orthodontic treatment. Dental pulp and dental papilla were separated immediately after extraction. Samples were divided into 3 experimental groups： Group 1, dental papilla of immature permanent tooth; Group 2, dental pulp of immature permanent tooth;Group 3, dental pulp of mature permanent tooth. RT-PCR and western blot techniques were used to detect the mRNA and protein expression of Notch2 respectively. Image analysis software Meta Morph was used to measure the gray scale of positively expressed bands, and β-actin was used as an internal control. The gray scale ratio of Notch2 and 13-aetin represented the Notch2 expression intensity. Two-sample f-test was performed by SPSS 11.0 statistical software. Results Notch2 was positively expressed in all the samples including dental papilla of immature permanent tooth, dental pulp of both immature and mature permanent tooth. Noticeably, the expression of Notch2 mRNA and protein in dental pulp of immature permanent tooth was significantly higher than that in dental papilla and dental pulp of mature permanent tooth（P 〈 0.05）. Conclusion Notch2 is expressed not only in dental pulp ef immature permanent tooth and mature permanent tooth but also in dental papilla of immature permanent tooth, while the expression intensityis different in the three groups, which suggests Notch2 might play a significant role in the development of pulp-dentin complex.