(来学网)FR矫治器的唇挡截面呈泪滴形,其下缘应在牙龈上方至少
  • A.
    (来学网)7.5mm
  • B.
    (来学网)6mm
  • C.
    (来学网)8.5mm
  • D.
    (来学网)7mm
  • E.
    (来学网)8mm