结果根管治疗失败的主要原因为根管继发感染、根尖超填及根尖周机械损伤。
Results Secondary infection of the root tubes , apex overfilled and peripheral mechanical injury were main failure factors in the treatment of root tubes .
目的：了解感染根管内产黑色素类杆菌（BPB）的定植情况，进一步探讨BPB与慢性根尖周炎临床症状的相关性。
OBJECTIVE To study the colonization of Black-pigmented bacteria(BPB)in infected root canals and discuss the correlation between Black-pigmented bacteria and clinical symptoms in chronic periodontitis.
牙髓根尖周病是一种主要由细菌感染引起的、机体免疫系统参与的疾病。
The periapical disease and the pulp disease are the endodontic disease which mostly caused by infection of bacterium and are connected with immune system.
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