Assess Mobility of Prosthesis
All implant-supported prostheses must be stable. To detect mobility, place an explorer or scaler under the embrasures and apply gentle pressure in the buccolingual direction, as well as slight tension in the apicocoronal direction. When mobility is present, assume that it originates at the prosthetic or component level, rather than from the implant itself. It is often difficult to distinguish mobility of the prosthesis from mobility of the abutments. If the prosthesis is mobile and there is no separation between the prosthesis and the abutment, this is a sign of loosening or fracture of the abutment screws.
In screw retained prostheses- two screws are involved: a screw attaching the prosthesis to the abutment and a screw retaining the abutment on the implant. Movement may be due to the loosening either or both screws.