Evaluation of the methods for dislodging the impression tray affecting the dimensional accuracy of the abutments in a complete dental arch cast

The dimensional accuracy of dies was evaluated in complete dental arch casts made by three different methods of dislodging the impression tray. By one method, the impression tray was dislodged parallel to the long axis of the abutment and by the other two the trays were inclined with the fulcrum at either the posterior or anterior region of the complete dental arch. The dimensional changes of the molar-die were significantly affected by the dislodging method in the inclined way but not those of the incisor-die. The anteriorly inclined method showed fewer dimensional changes than the posteriorly inclined method. On the other hand, the dimensional changes of the incisor-die were not significant by any dislodging method, but were observed when some impression material was used. If the impression tray is removed by the inclined way, the fulcrum should be chosen at a region remote from the abutment instead of at the proximal region.