gangrenous tooth

例句：

1. 1. The patient'smouth was so bad that the dentist hadto remove the gangrenous tooth.
   病人的牙齿坏到医生不得不拔除那根坏掉的牙齿。
2. 2. The necrotic periodontal disease had causedsevere pain and swelling in the patient's gums.
   坏死性牙周病导致患者牙龈严重疼痛和肿胀。
3. 3. Thenecrotic gum is a common symptomof diabetes, which can lead to complicationsif left untreated.
   坏死性牙龈是糖尿病的常见症状，如果不治疗可能会导致并发症。