(来学网)桩冠长度要求为
  • A.
    (来学网)根长的2/3~3/4
  • B.
    (来学网)牙体长度的2/3~3/4
  • C.
    (来学网)根长的1/2~3/4
  • D.
    (来学网)牙体长度的1/2~3/4
  • E.
    (来学网)越长越好