Abstract:

Objective    In the present study， we performed RET on beagle dogs'immature teeth with periapical periodontitis. This animal study aimed to explore the potential source of stem cells involved in RET. Methods    Totally eighteen immature premolars from three 6-month-old Beagle dogs were randomly assigned to normal control （NC）， apical periodontitis （AP）， RET-1 week， and -2 weeks （RET-1， RET-2）， and gelfoam-1 week and -2 weeks （GE-1， GE-2） groups （3 teeth/group）. Root canal contents were collected by irrigation for a cytospin smear after teeth were extracted and split， and MSCs were identified by immunocytochemistry using antibodies against STRO-1 and CD 105. Results    The number of MSCs was higher in the AP than in the NC group. MSC markers were detected in both RET and GE groups. Conclusion    MSCs in root canal after RET not only come from evoked bleeding but also come from outside root canal， which might be due to endogenous stem cell homing to the injured sites.

Key words: immature permanent tooth, periapical periodontitis, mesenchymal stem cells, regenerative endodontic treatment

摘要：

目的    应用比格犬建立年轻恒牙根尖周炎动物模型，并进行再生性牙髓治疗（regenerative endodontic treatment， RET），探究参与RET的间充质干细胞（mesenchymal stem cells，MSCs）的可能来源。方法    本研究于2013年12月至2014年7月在中国医科大学口腔医学院中心实验室完成。选择3只6月龄的比格犬，每只犬双根前磨牙6颗，共18颗牙，随机分为正常对照组、根尖周炎组、RET组（分为RET-1、RET-2组）以及明胶海绵组（分为Gelfoam-1、Gelfoam-2组），每组3颗牙。RET-1、RET-2组分别在封抗生素糊剂炎症控制后，刺破根尖周组织出血，常规行RET 1、2周后拔牙，劈牙，取根管内容物。明胶海绵组，不刺破根尖周组织，而是在根管内放明胶海绵，使之接触到根尖部；Gelfoam-1、Gelfoam-2组分别于放明胶海绵1、2周后拔牙，劈牙，取根管内容物。正常对照组与根尖周炎组牙齿于建立根尖周炎模型4周后拔除，劈牙，取根管内容物。内容物的PBS冲洗液经甩片后，用免疫荧光标记MSCs标记物STRO-1和CD105。结果    根尖周炎组根管内容物中STRO-1和CD105的阳性表达高于正常对照组。RET组和明胶海绵组，根管内容物中都可检测到MSCs标记物的表达。结论    进行RET时，根管内的MSCs可来源于刺破根尖周组织出血，也可能由内源性干细胞向根管内“归巢”而来。

关键词: 年轻恒牙, 根尖周炎, 间充质干细胞, 再生性牙髓治疗