Methods: Areas of subgingival calculus were selected from 6 freshly extracted human teeth with periodontal disease.

方法：选取6颗新近拔除的有明显龈下牙石的牙周病患牙。

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Methods: Areas of subgingival calculus were selected from 6 freshly extracted human teeth with periodontal disease.

方法：选取6颗新近拔除的有明显龈下牙石的牙周病患牙。

youdao