Dimensional Accuracy of Working Dies Fabricated by Different Impression Materials and Techniques: 3D Digital Assessment

Accuracy of dental impression plays a significant role in the success of definitive restorations. This study aimed to compare the dimensional accuracy of working dies fabricated using two different impression materials and techniques. Forty working dies fabricated from 40 impressions of preprepared mandibular first molar tooth replica stabilized in a jaw model to receive full coverage crown. Two different Polyvinyl siloxane (PVS) impression materials were used; Aquasil and Virtual. Two different impression techniques were used with each type of impression material; One-step and two-step. The working dies dimensional accuracy was measured in four dimensions and compared with that of the preprepared molar tooth replica using a digital caliper and 3D scanner. Based on a 3D scanner, there were a significant difference of dies fabricated by the two tested impression materials using the two-step impression technique in Mesiodistal-Gingival dimension (IIA and IIB) groups compared to the preprepared tooth replica with an average 0.370 μ m ( P < .005). A significant difference was observed of the dies fabricated by the two tested impression techniques using virtual impression. material in Mesiodistal Occlusal dimensions with an average 0.135 μ m ( P < .03), and in Mesiodistal-Gingival dimensions with an average 0.490 μ m ( P < .001) and Buccolingual-Gingival dimensions with an average 0.143 μ m ( P < .005) using Aquasil impression material compared to the preprepared molar tooth replica. Both impression materials (Aquasil and Virtual) and techniques (One-step and Two-step) used in this study produced working dies with clinically accepted dimensional accuracy.