An apparatus and a method for controlling a degree of attrition or wear of a sealing screw conveying plasticized material are provided. The apparatus includes an opening which intersects the wall of a housing of the screw in the region of the screw threads or in the region immediately neighboring the screw threads. Another opening intersects the wall of the housing. The two openings are spaced apart axially from each other and the pressure sensors connected to both openings. The process involved conveys a plasticized material against a resistance, the resistance being a sealing screw bearing supported within the screw housing. The pressure of the conveyed material is measured at two locations spaced apart from each other in the direction of conveyance. The two locations are disposed on both sides of a resistance body towards which the sealing screw conveys the material. The difference between the two measured values is used to indicate the degree of wear of the screw or its housing, respectively.