Accuracy of a New Fast-Setting Polyether Impression Material

Purpose: To evaluate the dimensional accuracy of impressions made using a new fast-setting polyether material. Materials and Methods: A metallic reference model with two crown preparations, one inlay preparation, and three stainless steel precision balls was digitized to create a digital reference model. Sixteen one-step impressions were made for each of the four study groups, differing in impression material (regularsetting polyether [RSP] vs fast-setting polyether [FSP]) and technique (monophase vs dualphase), for a total of 64 specimens. Plaster casts fabricated from these impressions were digitized using 3D scans. Global accuracy was studied by evaluating distance and angle deviations between the replica and the reference model. Local accuracy was described in terms of trueness and precision of the aligned individual abutment tooth surfaces. Results: For all impression materials and techniques, the local accuracy at the abutment tooth level was excellent. For surfaces prepared for crowns, mean trueness was 10 μm, and mean precision 12 μm. Inlay surfaces were associated with higher inaccuracies (mean trueness 21 μm and mean precision 37 μm). The greatest global inaccuracies were generally measured for the cross-arch span, with mean distance changes between –55 μm and –94 μm. For all aspects of studied accuracy, impressions with FSP were at least comparable to those fabricated with RSP. Conclusion: Within the limitations of this study, all tested polyether materials would allow for clinically acceptable impression making. The new fast-setting material could be an alternative to regular-setting polyether materials, especially for single crowns and small fixed partial dentures.