Dual-arch and custom tray impression accuracy.

This study compared the accuracy in three dimensions of casts made from complete-arch custom acrylic resin trays and two types of dual-arch impression trays. Using addition silicone impression material, 30 impressions (10/group) were made of a typodont. Reference marks on the typodont allowed measurements in the mesiodistal, buccolingual and occlusogingival dimensions. Gypsum casts were made and the distances between the reference marks on each cast were determined with a measuring microscope. The measurements from each cast were compared with one another and expressed as a percent deviation from the typodont measurements. Analysis with a two-way ANOVA and a Tukey B post hoc test established that the dual-arch trays were at least as accurate as the custom tray in every dimension measured.