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 .

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而对病变形态、边界、继发改变及其与周旧结构的关系及病变的整体判断优于A超。

But to the pathological change shape, the boundary, following sends the change and surpasses a with the week old structure relations and pathological change's whole judgment to surpass.

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