根管细菌渗漏体外模型的建立

目的：建立检测微细菌培养模型，以用于评价根管充填封闭情况。方法：牙根的冠根两端各连接一细菌培养储室，冠方储室置1mL无菌培养基并接种0．1mL菌液，根方储室起始为无菌培养基。每隔3d将冠方储室中菌液吸出1mL，并注入1mL新鲜BHI培养基，共90d。当根尖储室中培养基发生浑浊即为细菌渗漏发生，记录细菌渗漏发生时的天数。选择18个直根管前牙，其中牙胶充填组6个，用冷牙胶侧方加压充填技术充填；空管组6个，根管只预备不充填；根管密封组6个，根管充填并严密封闭根管口和根尖孔。用设计的模型检测密封状况。结果：全部空管组6个样本在1d内根方储室中出现浑浊；根管密封组6个样本的根方储室在90d内均未发生浑浊。牙胶充填组有2个样本分别在44d和46d发生浑浊。结论：此模型方法简单易行且实用有效，具有一定的临床相关性和可行性。

Establishment of an in vitro root canal model for evaluating bacterial endodontic leakage

AIM:To establish an in vitro root canal model for analyzing bacterial endodontic microleakage.METHODS:The root was mounted into an Eppendorf tube and the orifice was left opened in the Eppendorf tube (coronal chamber).The contacting area between the root surface and the Eppendorf tube was sealed,and the apical end of the root was placed in a glass bottle containing sterile Brain Heart Infusion (BHI).The coronal chamber was filled with 0.1 mL bacterial inoculum and the apical glass bottle was filled with 1 mL fresh BHI.Fresh BHI was added into the coronal chamber in a 3-day-interval and the turbidness in the apical glass bottle was observed daily for 90 days. Eighteen extracted single-root human anterior teeth were collected and divided randomly into three groups:the gutta-percha obturation group (6 roots) in which the canals were obturated using cold gutta-percha and lateral condensation technique;the vacant-canal group (6 roots) in which the canals were instrumented and left un-obtuarted; the hermetic-canal group (6 roots) in which the canals were obturated and the surfaces of the root (included the canal orifice and the apical foramen) were completely sealed.RESULTS:All vacant-canal canals showed bacterial penetration within 24 h,while the hermetic-canal canals remained uncontaminated throughout the 90 days of the test period.Two canals in the test group were found having bacterial leakage at the 44th and 46th day,respectively.CONCLUSION:The in vitro model designed is practicable and effective,it has, to some extent,the clinical relevance and feasibility.