An abutment for treating a screw-cement retained prosthesis is disclosed. The abutment comprises a screw hole formed upward and downward through an abutment body and a receiving portion for receiving a joining projection formed on an upper end of a fixture such that the receiving portion comprises a sticking groove stuck to an upper end of the joining projection and an allowance groove providing an allowance space, which causes the joining projection to be easily separated from and joined to the sticking groove.
