单项选择题
A.1ppm B.10ppm C.100ppm D.1000ppm E.10000ppm
A.10ppm B.500ppm C.1000ppm D.10000ppm E.1ppm
A.拔除 B.行活髓切断术 C.行根管治疗 D.直接盖髓 E.观察,暂不处理