Complete denture final impression trays: A method of delineating borders

Abstract

Correct extension of impression tray borders is necessary for accurate complete or partial denture final impressions. According to Jaggers et al.,’ more than half of the U.S. dental schools surveyed use irreversible hydrocolloid as the preliminary impression material of choice. This impression material has a tendency to displace the vestibular soft tissues, which will result in distorted borders on preliminary casts. If final impression trays are made from these casts, the desired borders of the trays should be marked so that they will not be overextended or underextended. Many complete and partial denture final impression techniques require trays that are approximately 2 to 3 mm short of the anticipated denture borders to accommodate (1) functional border-molding procedures and (2) final impression materials.2 The desired placement of final impression tray borders should be outlined on the preliminary cast by the dentist when the patient is not present for reference.