METHODS: Periapical biofilm samples of 25 teeth with periapical periodontitis were collected by periapical surgery and bacterial samples of root canals were taken from 20 of 25 teeth.

• 方法:按纳入标准通过根尖外科手术共收集25颗慢性根尖周炎患牙根尖生物膜样本,并同时采集其中20颗患牙的根管细菌样本。