A.先天缺失 B.恒牙外傷 C.嚴重的齲齒及并發(fā)癥 D.側(cè)切牙異位萌出 E.長期咬合創(chuàng)傷
A.20%~30% B.30%~40% C.40%~50% D.50%~60% E.60%~70%
A.500~600ppm B.600~800ppm C.800~1000ppm D.1000~1200ppm E.1200~1400ppm