[Effects of different tray types on the resulting impression].

In addition to the impression material the type of the used impression tray influences the accurat dimensional transfer of the teeth position to the master cast. In total 80 impressions were taken from models of the upper- and lower jaw by using condensation silicone, hydrocolloid, solid and perforated stock trays and acrylic custom trays. After that the casts were measured. The highest conformity with the original could be achieved with a hydrocolloid stock tray. The custom tray for the upper jaw showed short differences to the original model. By using a custom tray for the lower jaw higher dimensional changes occurred. Besides the different impression material thickness, distorsions of the trays should be discussed.